R2019-014 2019-01-28 RESOLUTION NO. R2019-14
A Resolution of the City Council of the City of Pearland, Texas,
amending the City's Engineering Design Criteria Manual.
BE IT RESOLVED BY THE CITY COUNCIL OF THE CITY OF PEARLAND,
TEXAS:
Section 1. That the City Council hereby amends the City's Engineering Design
Criteria Manual in accordance with Exhibit "A" attached hereto.
PASSED, APPROVED, AND ADOPTED this 14th day of January, A.D., 2019.
TOM REID
MAYOR
ATTEST:
NG e* N , T' C3 '
SE RETARY =
APPROVED AS TO FORM:
DARRIN M. COKER
CITY ATTORNEY
Memo
12/20/2018
DoE PE's To: Mayor and City
To: Clay Pearson, City Manager Council members
ci
To provide consistency and
From: Robert D. Upton P.E, Director of Engine- g & Pro,quality for public and private
IL x AS design, much of which
4.st. 10°' CC: Jon Branson, Deputy City Man.• -r becomes the City's long-term
Trent Epperson, Assistant Manager responsibility,we have a
Rajendra Shrestha, As ant Director of Engineerir design criteria manual.
That's been updated since
Date: December 21 .18 last review and coming to you
for consideration in January.
Re: Engineering Design Criteria Manual Update 2018 Clay
Background:
The Engineering Design Criteria Manual (EDCM) is intended to provide criteria to the
development and engineering community for the design of public infrastructure that would be
maintained by the City. The EDCM was last updated in October 2016 and formally adopted by
City Council. Since the adoption staff has been reviewing and making recommended changes to
update the EDCM to include more detail and direction for the engineering community. Staff
reviewed other cities, in the surrounding area, design manuals and incorporated some information
that will benefit the city. The updated EDCM is located at the following link.
Summary:
Below is a summary of the major changes for each chapter.
Chapter 1 -General Requirements: General updates to include relevant rules, regulations, and
definitions. Provided additional clarification regarding design requirements and construction
procedure requirements. Reflected the City moving forward with electronic submittals as well as
variances. Added a variance request form in Appendix B.
Chapter 2 - Construction Plan Requirements: General updates and clarification on
construction plan submittal requirements. Provided clarification on the documents required
(signed geotechnical report,traffic impact analysis, water and wastewater design analysis reports)
with the construction plan submittal. Providing additional criteria for water-sewer easements.
Updated the requirements for surveyor benchmarks. Included updates to requirements for work
within the floodplain.
Chapter 3—Water System Design: Included that the design engineer is to provide a water model
analysis for the project. This will be to provide verification that the system is designed in
accordance with the City's water model, water circulation and fire flows are provided. Require that
there is adequate circulation. Require that cul-de-sacs are to be looped for circulations. Provide
that dead end lines, if necessary, will end with a fire hydrant. Clarified installation testing
requirements for water lines. Provided further detail on material and appurtenances
requirements.
Chapter 4 — Sanitary Sewer Design: Provided additional general chapter clarifications.
Requirement that the design engineer provide a wastewater model analysis for the project.
Provided additional design criteria for gravity design, installation requirements, manhole
construction and coating requirements and information for lift stations. Provided further
clarification on sanitary sewer locations and crossings.
Chapter 5— Drainage System Design Criteria: Updated information in floodplain management
regarding the Community Rating System (CRS) program. Provided update to definitions and
formulas used to calculate the drainage reports. Clarification on design criteria with regard to the
water surface and hydraulic gradient and model requirements. Clarification on requirements for
detention on small, medium and large projects. Defined an extreme event spillway and provided
report style requirements. Design requirements is consistent with previous version.
Chapter 6 — Roadway Design Criteria: Updated general roadway design standards to include
definitions and requirements, provided updated road cross-sections, gated entrance standards,
and intersection visibility standards. Included pavement structure requirements and materials and
expanded driveway design and spacing criteria.
Chapter 7 — Traffic Design Criteria: This chapter has been updated to provide a more
compressive analysis and standardize the report of findings.
Chapter 8 — Stormwater Management: This chapter has been updated to include the Illicit
Discharge requirements.
Chapter 9—Traffic Signal Requirements: This is a new chapter that has been developed and
dedicated to the intersection requirements for traffic signals. This will provide the guidelines for
the equipment and standards that the City utilizes in the construction of traffic signals.
Chapter 10—Quality Control and Construction: This is a new chapter that has been developed
and dedicated to the management of quality control material testing for development. This will
provide the guidelines for private development engineers and contractors to follow when
constructing public infrastructure.
Chapter 11 —Graphic Standards and Drawings Requirements: This is a new chapter that has
been developed for the submission of construction plans for integration into the City's GIS
database. This will provide the guidelines for the engineering community to provide the as-built
plans in GIS formats for integration into the databases.
Chapter 12—Miscellaneous Requirements: This is a new chapter that has been developed for
the inclusion of design items that do not fall under the existing chapters of the EDCM.
Next Steps:
Staff intends to bring the EDCM to City Council for formal adoption in January 2019.
Previous Memos: 9/22/16
City of Pearland, Texas
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Engineering Design
Criteria Manual
December 2018
TABLE OF CONTENTS
CHAPTER 1: GENERAL REQUIREMENTS
1.1 General
1.2 References
1.3 Definitions
1.4 Preliminary Research
1.5 Fees
1.6 Design Review Requirements
1.7 Quality Assurance
1.8 Construction Procedure Requirements
1.9 Approval and Acceptance of Public Improvement Projects
1.10 Approvals and Variances
Appendix A: Checklist for Subdivision Acceptance
Appendix B: Variance Form
CHAPTER 2: CONSTRUCTION PLAN REQUIREMENTS
2.1 General
2.2 Required Plan Sheets
2.3 Design Requirements
2.4 Easements
2.5 Utility Locations '
2.6 Private Facility Locations
2.7 Crossings
2.8 Trench Safety
2.9 Street Lighting
2.10 Bench Marks
2.11 Residential Lots and Improvements
2.12 Flood Plain Management
2.13 Stormwater Management Plan
CHAPTER 3: WATER SYSTEM DESIGN CRITERIA
3.1 General
3.2 Design Requirements
3.3 Quality Assurance
3.4 Additional Standards
3.5 Extra Territorial Jurisdiction
CHAPTER 4: SANITARY SEWER DESIGN CRITERIA
4.1 General
4.2 Definitions
4.3 Design Requirements
4.4 Quality Assurance
4.5 Additional Standards
CHAPTER 5: STORM SEWER DESIGN CRITERIA
5.1 General
5.2 Drainage Policy
5.3 References
5.4 Definitions
5.5 Storm Sewer and Road-side Ditch Design Requirements
5.6 Hydrology Analysis Overview
5.7 Hydraulic Channel Design Criteria
5.8 Detention System Design
5.9 Miscellaneous Design Considerations
5.10 Report Requirements
5.11 Quality Assurance
Appendix A: Detention Storage Volume Calculations for Small and Medium Projects
CHAPTER 6: ROADWAY DESIGN CRITERIA
6.1 General
6.2 General Roadway Design Guidelines
6.3 Roadway Classifications
6.4 Geometric Street Design Standards
6.5 Gated Development Entrance Requirements
6.6 Public Right-of-Way Visibility Requirements
6.7 Pavement Structure Requirements
6.8 Reinforced Concrete Pavement Materials
6.9 Grading and Layout Requirements
6.10 Traffic Control Devices
6.11 Sidewalks
6.12 Driveways
6.13 Trails
CHAPTER 7: TRAFFIC DESIGN CRITERIA
7.1 Traffic Impact Analysis(TIA)
CHAPTER 8: STORMWATER MANAGEMENT
8.1 General
8.2 Definitions
8.3 Allowable Stormwater Discharges
8.4 Stormwater Pollution Prevention Plan(SW3P) Requirements
8.5 Best Management Practices
8.6 Post Construction Stormwater Management in New Development and
Redevelopment
8.7 Maintenance of Stormwater Facility
8.8 Stormwater and Illicit Discharge Ordinance
CHAPTER 9: TRAFFIC SIGNAL REQUIREMENTS
9.1 General
9.2 Traffic Signal System Design Guidelines
9.3 Construction Plan Requirements
9.4 Approved Products
9.5 Signal Activation
CHAPTER 10: QUALITY CONTROL&CONSTRUCTION MATERIAL TESTING REQUIREMENTS
10.1 General
10.2 References and Requirements
10.3 Pavement Subgrade
10.4 Concrete Pavement and Utility Construction Concrete
10.5 Asphalt Concrete Pavement
10.6 Cement Stabilized Sand
10.7 Bedding, Backfill, Embankments and Lot Fill
10.8 Utility Construction
CHAPTER 11: GRAPHIC STANDARDS& DRAWING REQUIREMENTS
11.1 General
11.2 GIS Standards and Data Requirements
11.3 CAD Standards and Data Requirements
11.4 AUTOCAD Drawing Layer Requirements
11.5 GIS Graphic Standards
CHAPTER 8: MISCELLANEOUS REQUIREMENTS
12.1 Barricades and Traffic Control
12.2 Approved Product List
12.3 City of Pearland Standard Construction Details
CITY OF PEARLAND
CHAPTER 1
GENERAL REQUIREMENTS
ENGINEERING DESIGN CRITERIA MANUAL
December 2018
Page 1 of 12 General
Requirements
CHAPTER 1
GENERAL REQUIREMENTS
1.1 GENERAL
1.1.1 These Standards describe the general requirements for the preparation of
construction plans and the supporting documents required for approval by
the City of Pearland. Specific.design requirements, in addition to these
standards, may be required by the City of Pearland.
1.1.2 Construction plans for public improvements within Pearland city limits
shall be approved by the City of Pearland. Construction plans for public
improvements within the City of Pearland extraterritorial jurisdiction(ETJ)
shall be reviewed and approved by Brazoria County Engineering
Department, respective Municipal Utility Districts, Brazoria Drainage
District No. 4, and City of Pearland.
1.1.3 Construction plans for private improvements that connect to or affect the
public infrastructure shall be approved by the City of Pearland as required
in the Site Development chapter of these standards and the Uniform
Development Code.
1.1.4 All projects that are required to conform to these Standards shall also
comply with all applicable City of Pearland ordinances.
1.1.5 All construction plans and supporting documentation shall conform to the
requirements of these Standards and regulations of all Federal, State,
County, and entities having jurisdiction. It is the responsibility of the
project engineer to use these standards professionally to produce a design
product conforming to acceptable engineering practices.
1.1.6 Any reference by this manual to any law, regulation, rule, publication, or
any other source shall refer to the most recently adopted, promulgated, or
otherwise effective version applicable as such may be amended from time
to time.
1.1.7 The Engineering Department shall review and maintain the Engineering
Design Criteria Manual. Any recommended changes to the Engineering
Design Criteria Manual shall be approved or disapproved by the City
Engineer. All approved changes will be summarized and updated to the
Engineering Design Criteria Manual at a frequency determined,but no less
than once every two years, by the Engineering Department.
Page 2 of 12 General
Requirements
1.1.8 The Engineering Department shall develop and maintain Standard
Construction Details. These Standard Construction Details shall be
maintained and updated periodically by the Engineering Department. These
documents are available on the engineering webpage and at the Engineering
Department for review upon request.
1.1.9 Engineering Department shall develop and maintain an Approved Product
List. This Approved Product List shall be maintained and updated
periodically by the Engineering Department.These documents are available
in the Engineering Department and are available for review upon request.
1.2 REFERENCES
1.2.1 All projects that are required to conform to these Standards shall also be in
compliance with all applicable City ordinances. All construction plans and
supporting documentation shall conform to the requirements of these Standards
and all applicable regulations of all Federal, State, County, and Local entities
having jurisdiction. Relevant related laws and regulations included but are not
limited to the following:
A. City of Pearland Ordinances
B. State of Texas
1. Texas Accessibility Standards (TAS), pursuant and subject to the
Texas Government Code, Chapter 469, and the Texas
Administrative Code, Title 16, Chapter 68
2. Rules and Regulations published by the Texas Commission on
Environmental Quality(TCEQ):
i. Rules and Regulations for Public Water Systems, Texas
Administrative Code, Title 30, Chapter 290, Subchapter D
ii. Design Criteria for Domestic Wastewater Systems, Texas
Administrative Code, Title 30, Chapter 217
iii. TCEQ storm water pollution prevention protection standards
3. State of Texas Engineering Practice Act, Texas Occupations Code,
Chapter 1001 Professional Land Surveying Practices Act, Texas
Occupations Code, Chapter 1071
4. Texas Manual on Uniform Traffic Control Devices.
C. National
1. Americans with Disabilities Act, 42 U.S.C. § 12101 et seq and
regulations, 28 CFR Part 36.
2. American Association of Highway and Transportation Officials, A
Policy on Geometric Design of Highways and Streets
3. Institute of Transportation Engineers, Traffic Engineering
Handbook
4. Highway Capacity Manual, National Research Council,
Transportation Research Board
Page 3 of 12 General
Requirements
1.3 DEFINITIONS
For the purposes of this manual, the following words and phrases shall have the
meanings respectively ascribed to them by this section.
Approved Products List — List of approved products that can be utilized for
construction in the city. This list may be updated periodically.
City Code—The code of Ordinances of the City of Pearland, Texas.
City Engineer-The City Engineer or his designee.
Collector Streets - Street routes that have short travel distances and collect traffic
from intracity streets and funnel it into major thoroughfares or other collector
streets.
Commercial Driveway Approach - The portion of a driveway within the public
right-of-way that provides access to property on which an office,retail commercial
center, or a building having more than three dwelling units is located or any
driveway approach which accesses property that is primarily used for a non-
residential purpose.
County —The applicable political subdivision of the State of Texas in which a
subject tract is located. Pearland city limits and its extra-territorial jurisdiction
covers portion of Fort Bend County, Harris County and Brazoria County.
Design Analysis - Narratives and calculations necessary to support design of a
project.
Drawings - Plan, profile, detail, and other graphic sheets to be used in a
construction contract, which define character and scope of the project.
Driveway - Entrance to and exit from premises where it is possible to park
completely off the street, and which is not open for vehicular traffic except by
permission of the owner of such private property.
Driveway Approach - A way or place including paving and curb returns between
the street travel lanes and private property that provides vehicular access between
the roadway and said private property.
Dwelling Unit-A building or portion thereof designed exclusively for residential
occupancy.
Page 4 of 12 General
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Engineering Department— Department develops, implements, and manages city
infrastructure for capital projects and residential and commercial development and
ensures that city infrastructure is designed and constructed per city standards.
Highway,Street, or Roadway-A general term denoting a public or private way for
the purpose of vehicular travel.
Infrastructure-Any facility or structure proposed to be constructed,reconstructed,
repaired, or regraded wholly or partially within right-of-way public easements or
connecting to right-of-way, including, but not limited to, streets, driveways,
sidewalks, curbs, gutters, culverts, open ditches, storm drains, and irrigation
facilities owned or maintained by a public entity.
Intersection - The area embraced within the prolongation or connection of the
lateral curb lines, or, if none, then the lateral boundary lines of two or more
roadways, including public street, private street, commercial driveway, residential
driveway, driveway approach,alley or combination thereof which join one another
at, or approximately at, right angles, or the area within which vehicles traveling
upon different roadways joining at any other angle may come into conflict.
Major Thoroughfare - Highways, streets and roadways devoted to moving large
volumes of traffic over long distances. Major thoroughfares shall be set forth in
the Major Thoroughfare Plan adopted by City Council and may be amended,
periodically.
Professional Engineer - An engineer currently licensed by and in good standing
with the Texas Board of Professional Engineers.
Professional Land Surveyor - A surveyor currently registered with and in good
standing with the State of Texas Board of Professional Land Surveying.
Project Engineer Representative — A representative of the design engineer who
possesses the knowledge,skills and abilities to carry out inspection duties to insure
compliance with the approved plans and specifications.
Private Projects or Private Improvements - All projects involving construction,
reconstruction, modification or maintenance of privately-owned/maintained
facilities including, but not limited to, buildings, parking lots, utility systems,
private shared access drives and any facility supporting functions within private
property boundaries.
Public Works Projects, Public Improvements or Public Projects — All projects
involving construction, reconstruction, modification or maintenance of public
infrastructure, including, but not limited to, streets, drainage facilities, water and
wastewater systems, construction in public rights-of-way or easements. Any
project that will be accepted for permanent maintenance by a public agency or
Page 5 of 12 General
Requirements
political subdivision of the State of Texas. Any project subject to review and
approval by the terms of Section 1.01 of this chapter.
Residential Developments - Residential developments shall mean all areas
identified as residential under the City of Pearland Zoning Ordinance or otherwise
zoned or devoted primarily to residential use.
Residential Driveway Approach - The portion of a driveway within the public
right-of-way that provides access to property on which a single-family residence,
duplex,or multi-family building containing three or fewer dwelling units is located.
Residential Streets- Street routes that provide access to local property owners and
which connect property to major thoroughfares or collector street networks.
Residential Structure - A single-family home, apartment house, townhouse,
condominium or any other type of dwelling unit.
Review Authorities-The authorized representatives of City departments,divisions,
or sections responsible for reviewing and approving calculations and drawings for
privately funded projects and for design and construction contracts with the City.
Right-of-way - Property that is publicly owned or upon which a governmental
entity has an express or implied property interest(e.g. fee title,easement,etc.)held
for a public purpose. Examples of such public purpose include by way of example
and not limitation, highways, streets, sidewalks, drainage facilities, sewerage and
water facilities.
Sidewalk—The section of pavement between the curb lines of a roadway and the
adjacent property lines or located within an easement intended for the use of
pedestrians.
Specifications - City of Pearland Standard Specifications plus project-specific
narrative descriptions of procedures, requirements, and materials for a particular
project.
Standard Construction Details—This is a separate document that contains the City
construction details and may be updated periodically.
Standards—The requirements of this design manual.
Traffic Impact Analysis-A study performed by engineers with expertise in traffic
engineering principles and practice which reviews development of a specific
property and how it integrates into the existing and proposed City of Pearland street
network. The analysis utilizes data and conclusions developed in previous studies
and identifies improvements needed to mitigate the impact of traffic generated by
a development on the street network system.
Page 6 of 12 General
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1.4 PRELIMINARY RESEARCH
1.4.1 Personnel from Public Works Department and Engineering Department will
be available for preliminary meetings to discuss a proposed project with the
project engineer and/or developer. The preliminary meetings are available
if the need for predevelopment meetings is not there, or to further clarify
discussions from the predevelopment meeting. This preliminary meeting
between the City and the engineer/developer should be scheduled with the
Engineering Department staff before submittal of any documents for
review. Predevelopment meetings should be scheduled through the
Community Development Department.
1.4.2 Research of all existing utility and right-of-way information with City,
County, State, and other public and private utility agencies shall be
completed and documented prior to submittal of any plans to the City. The
City will make the available information to the requester upon receipt of
Public Information Request(PIR) through City Secretary office.
1.5 FEES
1.5.1 Before beginning construction on a project,all applicable fees shall be paid
to the City.
1.6 DESIGN REVIEW REQUIREMENTS
1.6.1 Submit electronic copies of construction plans and supporting
documentation to the City via City of Pearland Community Web Portal
Engineering Department for review. Plans will be reviewed by the
appropriate departments using City's eTRAKiT system. The eTRAKiT
system will update the engineer/applicant about the status of approval which
may include pending, comments, approved etc. The City utilizes Manage
IT Program Management System for Capital Improvement Project during
design and construction Phase. If the project is a City of Pearland Capital
Improvement Project, all correspondence should be directed to the City
Engineer.
1.6.2 Based on the trip estimates for the proposed development by the design
engineer,a Traffic Impact Analysis may be required to determine necessary
traffic mitigation measures to maintain the required level of service as
dictated by City regulations and requirements. Refer to Chapter 7 for
further requirements.
1.6.3 Final Drainage plans within the jurisdiction of Brazoria Drainage District
No.4 must be approved and signed prior to submitting to City of Pearland
for approval.
Page 7 of 12 General
Requirements
1.6.4 The engineer must adequately address comments and provide written
response. Revised construction plan along with written responses shall be
submitted to the City via eTRAKiT system. For CIP, Manage_IT shall be
used for the submission of revised documents.
1.6.5 After final approval has been granted, an electronic copy of the plans will
be stamped by the City Engineer for approval.
1.6.6 If a project has begun the review process but becomes inactive for a period
of 12 months from the date of the last correspondence, the project will be
considered stopped. Projects re-activated after 12 months of inactivity will
be treated as new submittals,subject to all current requirements and changes
in codes or ordinances.
1.6.7 The project must be platted and recorded prior to final acceptance.
1.6.8 As warranted by scope and type of design, plans should be submitted for
review and approval by Texas Commission on Environmental Quality
(TCEQ).
1.6.9 As warranted by scope and type of design, plans should be in compliance
with Texas Accessibility Standards (TAC) and American with Disabilities
Act (ADA) regulations and criteria. Plans should be submitted to an
approved firm for such reviews and approvals.
1.6.10 The design engineer should be responsible for making sure that appropriate
permit approval are received prior to the construction. Such permit may
include; permit from US Army Corps,FEMA, TxDOT, etc
1.7 QUALITY ASSURANCE
1.7.1 Surveying and platting shall be accomplished under direction of a
Professional Land Surveyor. Recording documents shall be sealed,signed,
and dated by a Professional Land Surveyor.
1.7.2 Engineering calculations shall be prepared by or under the direct
supervision of a Professional Engineer trained and licensed in disciplines
required by the project scope and sealed by the Professional Engineer.
Final engineering design drawings shall be sealed, signed, and dated by the
Professional Engineer responsible for development of the drawings.
1.7.3 Final architectural design drawings shall be sealed,signed,and dated by the
licensed Architect responsible for development of the drawings.
Page 8 of 12 General
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1.7.4 Final landscape architecture design drawings shall be sealed, signed, and
dated by the licensed Landscape Architect responsible for development of
the drawings.
1.7.5 Final irrigation design drawings shall be sealed, signed and dated by either
a Texas Professional Engineer, a licensed irrigator or a licensed Landscape
Architect.
1.8 CONSTRUCTION PROCEDURE REQUIREMENTS
1.8.1 Construction shall not begin until construction plans are approved by the
City Engineer and until preliminary plat is approved, permits, bonds,
licenses, etc. have been obtained.
1.8.2 Coordinate with the Engineering Department forty-eight hours (48) in
advance to set up the pre-construction meeting for the project. Department
staff overseeing the construction process must attend the pre-construction
meeting,which shall be held at the Engineering Department or at the project
site.
1.8.3 Notify the Engineering Department at least three (3) business days prior to
beginning construction and at least twenty-four(24)hours prior to each time
concrete is placed on the project and prior to all required inspections or tests.
Inspections shall be conducted by the Engineering Department staff or any
designee as may be provided by the City.All Saturday construction shall be
scheduled with the Engineering Department at least forty-eight (48) hours
in advance. There will be no construction or inspections made on Sundays
unless in case of emergency. Request for Sunday or holiday construction
or inspections shall be made in writing and submitted to the Engineering
Department for approval not later than 72 hours prior to the intent. All
Saturday, Sunday or holiday inspections will be on a fee basis paid directly
to the City prior to final approval of the project.A schedule of fees is on file
in the Engineering Department.
1.8.4 Notify the Engineering Department office at least three (3) business days
prior to, any final inspection. The Engineering Department staff and
representatives of all entities having jurisdiction shall be present during all
final inspections (i.e., Public Works, Municipal Utility District, TCEQ,
TxDOT, etc.).
1.8.5 For acceptance of the project, the project engineer shall provide to the City
an electronic file copy(PDF format min. 400 dpi resolution), an AutoCAD
file (.dwg) or compatible .dxf file, and a GIS compatible file (see Chapter
2,and Chapter1 l for more electronic file options and requirements). Project
engineer shall provide to the Engineering Department the other project
completion deliverables such as Maintenance Bond,Affidavit of Bills Paid,
Page 9 of 12 General
Requirements
Engineer's Letter of Completion,applicable test results, etc. (See Appendix
A- Final Checklist for subdivision acceptance). All documents other than
the Maintenance Bond shall be in an electronic format.
1.8.6 Record Drawings (mark-ups) submitted by contractor to the project
engineer for the preparation of official Record Drawings shall include
verification (as applicable) of all manhole and junction box locations, line
sizes and lengths, elevations and inverts, lift station facility changes, fire
hydrants and valve locations, driveways, service lines locations and sizes,
changes to roadway profile and geometries, etc. Project engineer shall
modify plans accordingly and submit revised electronic plans as Record
Drawings for approval.
1.8.7 All delivery tickets for all materials(e.g., concrete, cement stabilized sand)
shall be maintained by the Engineer of Record and upon written request be
made available for review by the Engineering Department. These delivery
tickets shall be maintained for a maximum of one year from the completion
of the project.
1.8.8 Changes to approved plans shall be approved by the City Engineer prior to
construction. Any required changes during construction due to field
conditions or errors shall be discussed with the Engineering Department for
approval/coordination prior to making the change.
1.8.9 Engineering Department shall be on the distribution list for all construction
test results and reports.
1.8.10 Competent, full-time resident inspection by the Project Engineer's
representative shall be provided at all critical points of construction and as
deemed necessary by the City. Critical points of construction include, but
are not limited to,operations involving inspection of bedding and pipe prior
to backfilling, placing and compaction of backfill, placement of structural
concrete and paving, sidewalk placement and all on-site testing activities.
1.8.11 A certified testing laboratory shall be on site to perform applicable tests
required so that construction practices and materials conform to plan and
specification requirements.
1.8.12 All disturbed areas must be properly re-vegetated (minimum 70%
established grass cover on unpaved area) prior to demobilization and
acceptance of project.
1.9 APPROVAL AND ACCEPTANCE OF PUBLIC IMPROVEMENT
PROJECTS
Page 10 of 12 General
Requirements
1.9.1 Public Improvement projects shall have final approval by the City Engineer
prior to placing the facilities in service.
1.9.2 The Project Engineer shall also issue a certificate, at the completion of the
work, acknowledging that the project was constructed in accordance with
the City approved plans, specifications and special provisions.
1.9.3 All items listed in "Appendix A — Final Check List for Subdivision
Acceptance" must be met prior to final approval by the Engineering
Department.
1.9.4 Final approval will be documented in writing by the City Engineer.
1.9.5 Public Improvement projects within the City of Pearland will be subject to a
minimum two (2) year maintenance period. An inspection prior to the end
of the maintenance period shall be conducted by the Engineering Department
and all other entities having jurisdiction. All facilities shall be operational
and in good condition prior to final acceptance of a project in order to obtain
the refund of the maintenance bond.
1.9.6 The Engineer or Developer is required to comply with the Storm Water
Pollution Protection Plan (SWPPP) developed for the development and for
the implementation and maintenance of the Best Management Practices
(BMP). Once the project is complete and the final BMPs are installed, the
Engineer or Developer shall maintain the BMPs until revegetation is
established to prevent sediment transport and erosion. The Engineer or
Developer is responsible for the removal of BMPs once the revegetation is
established. These BMPs shall be removed within 30-days once the
revegetation has been reestablished. This will be reviewed during the two-
year maintenance period as described in Section 1.9.4.
1.10 APPROVALS AND VARIANCES
1.10.1 Approvals required in these Standards are the responsibility of the Owner.
Failure to obtain appropriate approvals may be grounds for suspension of
construction until appropriate approvals are granted. Items that do not
conform to these Standards shall be submitted for a variance request.
1.10.2Variances from these Standards are authorized only if approved in writing by
the Engineering Department. Variances must be submitted at the time of the
original construction plan submittal. Persons seeking a variance from these
Standards shall submit to the Engineering Department a written variance
request application on a form (Appendix B) provided by the City with the
applicable fee. Variance request applications should be submitted with
pertinent information such as construction plans or a right-of-way use permit.
Incomplete variance request applications will not be processed until the
Page 11 of 12 General
Requirements
applicant adequately addresses all outstanding items.It is the applicant's sole
responsibility to adequately support all requested variances. The City's
standard variance request application form is included at the end of this
chapter.
1.10.3 Construction work related to any specific approval item or variance that has
not been approved in writing should not begin until the City Engineer has
granted written approval. Any work that proceeds without specific approval
will be subject to removal and replacement in accordance with these
Standards.
1.10.4Materials and manufactured items used in construction of public
improvements shall conform to the City's Standard Specifications. Water,
wastewater and drainage system appurtenances shall be subject to the
approved items as listed in the Approved Products List and City of Pearland
Standard Construction Details available from the Engineering Department
and City website. Items not appearing on the approved list shall not be used
for construction of public works facilities in the City of Pearland.
1.10.5A11 projects that are required to conform to these Standards shall also comply
with applicable City Ordinances.Projects should be reviewed for compliance
with the Zoning, Subdivision, Floodplain Management, Signage, Traffic,
Water, Sewer, Stormwater Management, and any other applicable
Ordinances.
Page 12 of 12 General
Requirements
Appendix A
Final Checklist for Subdivision Acceptance
FINAL CHECK LIST
FOR
SUBDIVISION ACCEPTANCE
Name of Subdivision:
Name of Developer:
Name of Contractor:
ITEMS
1. Field Compliance
(A) Bench Marks, Brass Caps to be set with following information:
1. Elevation
2. Date of Adjustment
3. Surveyor's number
(B) Location and elevation to be furnished to City
2. Construction Plans:
Developer's Engineer has furnished City with complete set of scanned recorded
drawings and GIS files (See Chatter 2 and Chapter 11) for the subdivision on CD
(PDF file format, 400 DPI minimum)
3. Water Distribution Construction Checklist submitted by the
Developer's engineer.
4. Statement from County Tax Collector as to ownership and status
of State, County, School District and City taxes.
5. Two Year Maintenance Bond (original) in amount of 50% of construction
costs.
6. Contractor's affidavit of all bills paid.
7. Cost for two (2) years operating cost for the total number of
Lights installed.
8. All street signs as required within the subdivision.
9. Engineers certification letter.
Page 1 of 2
10.Total linear feet of storm sewer pipe.
11.Total linear feet of sanitary sewer pipe.
12.Total linear feet of concrete streets.
13.Total linear feet of water lines.
4" water line
6" water line
8" water line
12"water line
14.Deposit for building thoroughfare (if any).
15.Inspection Fee of 1% with engineer's estimate
(Due at time of construction with approved construction plans)
16.Perimeter Sidewalks (6' or 4')
17.Lift Station
a. Dimensions of wet well
b. Number, manufacturer, and type of pumps
c. Size of pump, flow and Hp of pumps
Submitted by:
Engineer of Record Date
Reviewed by:
Construction Inspector Date
Approved by:
City Engineer Date
Page 2 of 2
Appendix B
Variance Form
Os' olio,PfI4� City of Pearland
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t 2559 Hillhouse Rd TEMP
PEARJAND Pearland, Texas 77584
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sr i 89' pearlandtx.gov
Engineering Design Criteria Manual (EDCM)
VARIATION PROCEDURE •
Variation to any technical standard in the infrastructure standards may be permitted by the City if
a proposal is submitted by a registered professional engineer following generally accepted
engineering standards for traffic,sidewalk and other infrastructure as applicable,and such proposal
contains the following information and substantiates the findings in paragraph four(4)below:
PROJECT NAME:
PROJECT ENGINEER:
SUBMITTAL DATE:
RECORDED SUBDIVISION NAME:
This entire form must be submitted complete. If form is submitted incomplete, it will be
administratively rejected.
VARIANCE LOCATION:
A proposal must contain the following information and substantiate the findings in
paragraph four(4) below:
SPECIFIC PROPOSED DEVIATION FROM TECHNICAL STANDARD:
2. IMPACT OF DEVIATION: Set forth the relative factors such as speed differential and street
capacity,the likelihood of accidents,the long term maintenance and operation effect,the degree
of functionality and efficiency, the technological advancements involved, and other relevant
matters.
3. COMPARISON OF TECHNICAL STANDARD TO PROPOSED DEVIATION: Show the
proposed deviation with respect to relative factors such as overall safety and quality, traffic
speed differential,street capacity,existing and projected accidents, long-term maintenance and
operation,degree of functionality,degree of efficiency,technological advancements, and other
relevant matters.
4. MITIGATING IMPROVEMENTS THAT REDUCE NEGATIVE IMPACT: Describe for
example: overall safety and construction quality, traffic speed differential, street capacity,
accident occurrences, long-term maintenance and operation,degree of functionality, degree of
efficiency and demonstrating the degree to which the proposed deviation detrimentally affects
the foregoing. Other relevant factors, including technological advances, should be explained
by describing how they will affect the proposed deviation. Mitigating improvements can
include, but are not limited to, traffic control devices, pavement improvements, added
acceleration or deceleration lanes or reservoirs, and other on-site improvements.
UMMARY& CONCLUSION/RECOMMENDATION FOR VARIANCE:
Supporting Documentation Attached. Yes No
Signature and Seal of Professional Engineer:
ENGINEERING DEPARTMENT USE ONLY
Reviewed By:
Engineering Department Reviewer Date
Variance Request Approved/Denied By:
Copies of Backup Information/Notes Attached
City Engineer Date
CITY OF PEARLAND
CHAPTER 2
CONSTRUCTION PLAN REQUIREMENTS
ENGINEERING DESIGN CRITERIA MANUAL
December 2018
Page 1 of 15 Construction Plans Requirements
CHAPTER 2
CONSTRUCTION PLAN REQUIREMENTS
2.1 GENERAL
2.1.1 This chapter includes the graphic requirements for engineering
drawings submitted for review and permitting to the City of Pearland.
2.1.2 The City Engineer shall approve construction plans for public
improvements within the City of Pearland city limits or extraterritorial
jurisdiction.
2.1.3 Construction plans for private improvements, within public rights-of-
ways and public easements that connect to or affect the public
infrastructure shall be approved by the City of Pearland subject to the
requirements of this manual and are subject to review and approval
using the process defined in this manual.
2.2 REQUIRED PLAN SHEETS
2.2.1 Cover Sheet
2.2.2 Approved Plat (latest version of the approved plat shall be included in
the Record Drawings)
2.2.3 Construction Notes and Legend
2.2.4 Topographical Survey Map
2.2.5 Overall plan Layouts for proposed improvements
2.2.6 Permanent Street Signage Plan
2.2.7 Drainage Area Map and Calculations
2.2.8 Lot Grading Plan showing Existing and Proposed Spot Elevations
2.2.9 Plan and Profiles
2.2.10 Detention Pond Plan and Details, as Applicable
2.2.11 Traffic Control Plans and Details,as Applicable
2.2.12 Pavement Marking and Signage, as Applicable
2.2.13 Specific Construction Details
2.2.14 Storm Water Pollution Prevention Plans and Details
2.2.15 Standard City of Pearland Construction Details
2.3 DESIGN REQUIREMENTS
2.3.1 The seal,date, and signature of the engineer responsible for preparation
of the plans is required on each sheet in compliance with the rules and
regulations of the Texas Board of Professional Engineers (TBPE). The
engineer may use TBPE-accepted electronic seal, date, and signature.
Page 2 of 15 Construction Plans Requirements
2.3.2 Signature Block: Construction plans for public improvements shall
contain a Signature Block for approval for the Director of Public Works
and for the City Engineer. Signature Blocks shall include the statement,
"Approval void if progress has not been made toward completion of
project within one year of date of signature."
2.3.3 A benchmark elevation and description is required on each sheet along
with flood plain information for the project. Date of datum adjustment
for the benchmark shall be noted in plans. Benchmark should be tied to
City monuments with datum adjustment factor when applicable.
2.3.4 Each sheet in the plans on which elevations are marked shall include the
vertical datum and adjustment, consistent with the effective FIRM,
along with the site benchmark used for vertical control; except that, if
the plan elevations are not on the same vertical datum as the base flood
elevations shown on the effective FIRM, each sheet in the plans on
which elevations are marked shall also show tabulated vertical datum
differences.
2.3.5 Label each plan sheet as to street right-of-way widths,pavement widths
and thickness,type of roadway materials,curbs,intersection radii,curve
data, stationing, existing utilities type and location, etc. Please check
Chapter 11 for graphical requirement of the construction plan.
2.3.6 Stationing must run from left to right except for short streets or lines
originating from major intersection where the full length can be shown
on one sheet.
2.3.7 A north arrow is required on all appropriate sheets and should be
oriented either upward or to the right. This requirement may be waived
under the following conditions: a storm or sanitary sewer whose flow
is from west to east or from south to north and a primary outfall ditch
whose flow is form west to east or from south to north.
2.3.8 Show all lot lines, property lines, rights-of-way lines, and easement
lines. Provide grading elevation at each corner of lot.
2.3.9 A cover sheet shall be required for all projects and clearly identify any
proposed variances unless approved by the City Engineer. All plan
sheets should be listed by sheet number on the cover sheet. A vicinity
map should always be included to show the project location. A City of
Pearland signature block shall be provided. Cover sheet should include
engineering firm's registrations number.
2.3.10 If a roadway exists where plans are being prepared to improve or
construct new pavement or to construct a utility,this roadway should be
Page 3 of 15 Construction Plans Requirements
labeled as to its existing width, type of surfacing, and base thickness if
available. Pavement thickness can be ascertained by coring. When
complete the core hole shall be filled full depth with concrete
immediately after completion to protect pavement prior to construction.
2.3.11 Plans prepared for the City of Pearland shall be prepared using
permanent ink, photographic or other approved process on paper. All
plans shall be submitted electronically.
2.3.12 Do not place match lines in intersections.
2.3.13 Service areas outside of project boundary shall be delineated on the arial
map.
2.3.14 All utility lines four inches (4") in diameter or larger within the right-
of-way or construction easement should be shown in the profile view.
All utility lines,regardless of size should be shown in the plan view.
2.3.15 Show flow line elevations and direction of flow of all existing ditches
and culverts.
2.3.16 Show natural ground profiles along the centerline and each right-of-way
or easement line except as required below. When there is a difference
of less than 0.5 feet, one right-of-way profile is sufficient.
2.3.17 Resolve all known conflicts of proposed utilities with existing utilities.
2.3.18 Plans shall be standard twenty-two inch by thirty-four inch (22"x34").
All half—size plans shall be to exact half scale. All plans submittal shall
be electronic(minimum 400 DPI to scale)
2.3.19 Details of special structures not covered by approved standard drawings,
such as stream and gully crossing, special manholes, etc., should be
drawn to scale with the horizontal and vertical scales equal to each other.
2.3.20 Plans shall be drawn to accurate scale, showing proposed pavement
typical cross-sections and details, lines and grades, and all existing
topography within the street rights-of way; and at intersections, the
cross street for designing adequate street crossings.
2.3.21 Grades should be labeled for the top of curb except at railroad crossings.
Centerline grades are acceptable only for paving without curbs and
gutters.
2.3.22 Curb return elevations and grades for turnouts shall show in the profile.
Page 4 of 15 Construction Plans Requirements
2.3.23 Gutter elevations are required for vertical curves where a railroad track
is being crossed.
2.3.24 The surface elevation at the property line of all existing driveways
should be shown in the profile.
2.3.25 Station all esplanade noses affected by proposed construction, both
existing and proposed.
2.3.26 Station all points of curvature, points of tangency, and points of
intersection in the plan view. Station all radius returns and grade change
points of intersection in the profile with their respective elevations.
2.3.27 The standard scales permitted for plans and profiles of paving and utility
plans are as follow:
A. Major thoroughfares or special intersections/situations:
1"=2' Vertical; 1"=20' Horizontal
B. Minor Streets:
1"=5' Vertical; 1"=50' Horizontal or
1"=4' Vertical; 1"=40' Horizontal or
1"=2' Vertical; 1"=20' Horizontal
C. The scales described above are the minimum allowable. Larger
scales may be required to show details of construction.
D. A scale bar is required on all appropriate sheets.
E. Deviations to these scales can only be allowed with the prior
approval of the Engineering Department.
2.3.28 In addition to the plan and profile sheets described above, each set of
construction drawings shall contain paving and utility key drawings
indexing specific plan and profile sheets. Overall layouts may be drawn
at a scale of one inch equals one hundred feet (1" = 100') or one inch
equals two hundred feet(1"=200').
2.3.29 Standard City details,where applicable, shall be included.
2.3.30 Construction plans shall include a legend describing standard symbols
that may not be described in the plans.
2.3.31 All property ownership and easement information will be shown in the
construction plans with all proper information associated with it. Fort
Bend County, Harris County and/or Brazoria County recording
Page 5 of 15 Construction Plans Requirements
information,whichever is applicable,shall be shown in the construction
plans.
2.3.32 When ownership, easement, and right-of-way recording information is
not shown on the plat included in the plans, this information shall be
shown on Construction plan sheets.
2.3.33 The City shall be provided with a pdf(minimum 400 DPI)of final plans
and eventually Record Plans on an electronic format. Additionally,City
shall be provided with the electronic files of construction plans in one
of the following formats, as appropriate: Geodatabases (personal
geodatabase,file geodatabase,ArcSDE geodatbase),Shape files(.SHP),
DXF (AutoCAD, current version), DWG (AutoCAD, current version),
DGN (5.x to 8 Microstation), LizardTech MrSID and MrSID Gen 3
(.SID)Aerial photos—for raster data(images).
2.3.34 Coordinate points for project controls or various project points as
deemed necessary by the engineer shall be based on Texas Coordinate
System, South Central Zone, NAD 83. Coordinates shall be Surface.
Vertical datum is based on NAVD88 with 2001 Adjustment
2.3.35 Construction plan review submittals shall include a signed and sealed
copy of the relevant Geotechnical Report.
2.3.36 Construction plan review submittals shall include a signed and sealed
copy of the traffic analysis report as warranted and determined to be
necessary at the discretion of the City Engineer.
2.3.37 Construction plan review submittals shall include a signed and sealed
copy of drainage analysis report to provide background data and
information needed to support design calculations.
2.3.38 Construction plan review submittals shall include a signed and sealed
copy of the water and wastewater design analysis report to provide
background data and information needed to support the design.
2.4 EASEMENTS
2.4.1 All easements and recording information, existing and proposed, shall
be shown in the construction plans in accordance with Section 2.
2.4.2 Storm sewer, sanitary sewer, and water line easements shall be
dedicated for the specific intended use.
2.4.3 Public utility easement requirements for a sixteen-foot (16') easement
are as outlined in the"Typical Utility Location in 10-Foot Wide and 16-
Page 6 of 15 Construction Plans Requirements
Foot Wide Easement Back-to-Back Lots and 14-foot Perimeter Lots"
drawing prepared by the Utility Coordinating Committee for
Metropolitan Area, Effective June 1, 1971. The public utility easement
width for dry distribution lines may be ten feet (10'). Perimeter
easement may be eight feet (8') by eight feet (8'), provided that the
easement is dedicated by separate instrument or special notes on the
plat.
2.4.4 Water line easements — the following minimum width easements are
required when facilities are not located within public street rights-of-
way or water line easements (as required in Chapter 3):
A. Fire hydrants located outside of public rights-of-way or water line
easements shall be encompassed by a ten-foot by ten-foot (10'x10')
exclusive,easement. Fire hydrants shall not be located within any other
type of easements.
B. Water meter easements shall be exclusive and should be located
adjoining a public right-of-way or water line easement.
C. Two-inch (2") and smaller meters serving non-residential and multi-
family developments shall be set in five-foot by five-foot (5'x5')
exclusive water meter easements.
D. Three-inch(3") and larger meters shall be set in a minimum of ten-foot
by twenty-foot(10'x20') exclusive,water meter easements.
E. When approved by the City Engineer, water mains may be located in
easements not adjacent to public street rights-of-way. These water
mains shall be centered in a twenty-foot(20')wide exclusive easement
restricted to water only.
F. For new construction, any water main, except at a fire hydrant, located
less than five feet (5') from the right-of-way line and within the right-
of-way shall have a water line easement adjoining the right-of-way.
Water line easements adjoining a right-of-way shall have a minimum
width of fifteen-feet(15').
G. Water mains should be located at the center of a twenty-foot(20')water
line easement,provided the easement adjoins the public right-of-way.
2.4.5 Sanitary Sewer Easements
A. Sanitary Sewers shall be designed and located to conform to regulations
of the Texas Commission on Environmental Quality. Sanitary sewer
easements shall be dedicated for the specific intended use. Easements
for a specific facility shall be exclusive and shall not overlap other
Page 7 of 15 Construction Plans Requirements
easements,except to cross the other easements.The following minimum
width easements are required when facilities are not located within
public street rights-of-way or sanitary sewer line easements.
B. The width of all exclusive sanitary sewer easements shall be equal to
the depth of the sewer from finished grade plus two (2)pipe diameters.
Sewer shall be located in the center of the easement. The minimum
width of a sanitary easement shall be twenty feet(20')when split along
a lot line, and twenty feet (20') wide for easements located within a
single lot.
C. Exclusive sanitary sewer easement adjoining a public right-of-way shall
be fifteen feet(15').
D. Exclusive easements for force mains of all sizes shall have a minimum
width easement of twenty feet (20') for a single force main where the
force main is not located adjacent to a public right-of-way. Where the
force main is located in an easement adjacent to public rights-of-way,
the force main may be located at the center of a fifteen foot (15')
easement. Where the force main is located less than five feet(5') from
the right-of-way line within the public right-of-way, the minimum
easement width shall be fifteen feet(15') adjacent to the right-of-way.
E. Combined storm and sanitary sewer easement shall have minimum
widths as required in Section 2 for storm sewer easements.
Additionally, the sanitary sewer main, trunk or force main shall be
located such that the centerline of the pipe shall be at least half the width
of the easement, defined in Section 2, but not less than seven and one-
half feet(7.5'), from the edge of the pavement.
F. For combined storm and sanitary sewer easements located adjacent to
public rights-of-way where the sanitary sewer is located along the
outside of the easement, the centerline of the sanitary sewer pipe shall
be at least half the width of the easement defined in Section 2, but not
less than seven and one-half feet (7.5') from the outside edge of the
easement.
G. Where sanitary sewers or force mains are installed in easements
separated from public rights-of-way by other private or utility company
easements, the sanitary sewer easement should be extended along or
across the private utility company easement to provide access for
maintenance of the sewer or force main.
2.4.6 Storm Sewer Easements -the following minimum easement widths are
required:
Page 8 of 15 Construction Plans Requirements
A. The minimum width shall be twenty feet (20') with the storm sewer
centered in an exclusive easement, except as approved by the City
Engineer.
B. For storm sewers greater than ten feet (10') and less than fifteen feet
(15') in depth, the minimum width of an exclusive easement shall be
twenty-five feet(25').
C. For storm sewer greater than fifteen feet (15') in depth, the minimum
width of an exclusive easement shall be determined by the City
Engineer.
D. For all easements specified in Section 2.3.6,a minimum distance of five
feet(5')must be maintained from the easement line to the outside edge
of the storm sewer.
E. Where approvals are granted for a special use or combination easement
located along side lot or back lot, the minimum width shall be twenty-
five feet (25'). The easement width shall meet or exceed all other
easement requirements.
F. For specifically approved storm sewers located in an exclusive
easement adjacent to public rights-of-way, the minimum easement
width shall be ten feet(10'). The easement width shall meet or exceed
all other easement requirements.
2.5 UTILITY LOCATIONS
2.5.1 All utilities shall be underground with the exception of electric primary
lines. The electric primary lines,defined as feeders or three phase lines,
should be located around the subdivision perimeter whenever possible.
2.5.2 Water Main Location
A. All water mains shall be located within a public right-of-way or within
dedicated water main easements. The location of water mains within a
public street right-of-way is described in Chapter 3.
B. Water mains shall not be located in combination easements without the
approval of the City Engineer.
2.5.3 Sanitary Sewer Location
A. Sanitary sewers of twelve inches (12") or larger in diameter are usually
located within a public right-of-way or an easement adjoining the right-
of-way. Large sanitary sewers shall be located within the public street
right-of-way in accordance with Chapter 4. Sanitary sewers may be
Page 9 of 15 Construction Plans Requirements
located in exclusive or combination easements provided the easement
widths comply with Section 2, above.
B. Sanitary sewers shall not be located in side lot easements without the
approval from the City Engineer.
C. Sanitary sewers should be located within the right-of-way between the
property line and the back of curb on the opposite side of the right-of-
way from the water main.
2.5.4 Storm Sewers
A. Storm sewer shall be located in the public street right-of-way in
accordance with Chapter 5.
B. All storm sewer lines shall be located within public rights-of-way or
approved easements. Placement of a storm sewer in side lot and back
lot easements is discouraged. Approval from the City Engineer for the
use of side lot or back lot easements for storm sewers should be obtained
prior to plan preparation.
2.6 PRIVATE FACILITY LOCATIONS (Not Including Landscaping)
2.6.1 Installation of private facilities, including utilities,in public road rights-
of-way and their adjoining easements shall be approved by the City
Engineer.
2.6.2 Private facilities shall not conflict with other facilities in the right-of-
way and shall not be located in exclusive easements as required in these
Standards. All structures within the public right-of-way require
approval from the City Engineer and shall be located so as to not
interfere with existing or proposed public facilities.
2.6.2 All facilities in the right-of-way shall be located at least two feet (2')
behind the curb and all underground facilities in the right-of-way shall
be located at least two and one-half feet(2.5') below the top of curb on
a public street.
2.6.3 Private facilities shall be constructed in accordance with construction
plans approved by the City Engineer.
2.6.4 Landscaping within the public right-of-way or adjoining easements
shall not affect public utilities or traffic visibility.
2.7 CROSSINGS
Page 10 of 15 Construction Plans Requirements
2.7.1 Highway Crossings -All State and County Roads
A. State maintained Highway and Farm to Market Road crossings shall be
constructed in accordance with the requirements of Texas Department
of Transportation.
B. A water main, sanitary sewer, or force main shall be encased in a steel
pipe casing extending from right-of-way to right-of-way.
C. County road crossing shall be constructed in accordance with the
County's requirements.
D. Where additional right-of-way has been acquired or will be required for
future widening,the casing,where required, should be carried to within
ten feet(10') of each future right-of-way line.
2.7.2 Street Crossings
A. All water main and sprinkler line crossings under major thoroughfare
boulevards shall be encased. For all water mains, steel casing shall be
used, and for fire sprinkler lines PVC pipe, SDR 26 shall be used.
B. Conduits and sewers that do not carry liquid under pressure may be
bored and jacked into place without an encasement pipe.
C. Crossings under existing concrete streets, other than major
thoroughfares and collectors, shall be constructed by boring and
jacking. PVC pipe shall be jacked into place using equipment designed
for that purpose. Water may be used to facilitate the boring and jacking
operations. Jetting the pipe main into the place will not be permitted.
When conditions exist that warrant open cut across an existing street,
approval by the Engineering Department is required.
D. All open cut installations under existing or proposed streets shall be
backfilled as shown in the City of Pearland Standard Construction
Details.
E. All street crossings shall be constructed in accordance with construction
plans approved by the Engineering Department. All street crossings
shall be inspected by the Engineering Department. All street crossings
shall meet the requirements of these Standards.
2.7.3 Railroad and Pipeline Crossings
A. For railroad crossings, the carrier pipe shall be encased in steel pipe
casing extending from right-of-way to right-of-way.
Page 11 of 15 Construction Plans Requirements
B. All construction within the railroad or pipeline right-of-way shall
conform to minimum requirements set out in the agreement with the
owner of the right-of-way and/or easement.
C. Copies of the permits and/or agreements from the railroad or pipeline
shall be provided with the Major Construction Improvement permit
application to the Engineering Department
2.7.4 Ditch and Stream Crossings
A. Aerial crossing attached to the bridge structure is preferred by the City.
B. Where existing or proposed bridges have sufficient space and structural
capacity for installing water mains or conduits (twelve inches (12") or
smaller) under the bridge, but above the top of the bent cap elevation,
such installation will be permitted upon approval of the construction
plans. In all cases, the water main or conduit shall be above the bottom
chord of the bridge and eighteen inches (18") above the 100-year water
surface elevation. All conduits attached to a bridge shall be constructed
using steel pipe and shall extend a minimum of ten feet(10')beyond the
bridge bent or to the right-of-way line,whichever is greater. All conduit
attached to a bridge shall be maintained by the owner of the conduit or
will be subject to removal.
C. Separate,free-standing crossings across drainage ways are not typically
allowed. Project engineer to receive prior approval from the
Engineering Department prior to design if such installation is necessary.
D. All stream or ditch crossings shall be constructed of steel piped from
right-of-way to right-of-way.
2.8 TRENCH SAFETY
2.8.1 All construction within the City of Pearland and its extraterritorial
jurisdiction shall conform to federal and state requirements. Trench
safety is required for all excavations greater than five feet(5')in depth.
The contractor shall prepare or obtain the appropriate safety systems,
including current OSHA standards for trench safety. Design of trench
safety systems, sealed by a licensed professional engineer, shall be
submitted by the contractor prior to the execution of work.
2.9 STREET LIGHTING
2.9.1 Installation of street lighting shall be mandatory along all public streets
in the City of Pearland. In addition, the installation of street lighting is
strongly encouraged along existing or repaved streets. Street lighting
plan should be coordinated with the Engineering Department. For areas
Page 12 of 15 Construction Plans Requirements
in the Extraterritorial Jurisdiction (ETJ) of the City of Pearland, street
lighting shall be required and reviewed by the Engineering Department
in accordance with these Standards.
2.9.2 The location of street lights will be designed to maintain approximately
200' of spacing and shall be reviewed and approved by the Engineering
Department.
2.9.3 Private lighting systems may supplement or replace all or a portion of
the public street lighting as long as the net result provides equivalent
lighting to the standard set herein. A perpetual entity, such as an
incorporated homeowners association and/or an appropriate private
entity, shall notify the Engineering Department of its agreement to pay
for the operation, maintenance, and insurance of a private lighting
system prior to installation of the system. The system shall be approved
by the Engineering Department.
2.9.4 Street lights shall be designed in accordance with the design and
luminance requirements set out by AASHTO in the latest edition of the
Roadway Lighting design Guide. All public rights-of-way street
lighting systems shall include only light fixtures CenterPoint Energy
makes available to the City of Pearland.
2.10 BENCH MARKS
2.10.1 A secondary bench mark shall be set in each subdivision section or at a
spacing of one mile, whichever is greater. The benchmark shall have
an elevation based on the North American Vertical Datum of 1988,2001
adjustment. If a project vertical datum is not on the same vertical datum
as shown on the effective FIRM, a table with vertical datum difference
shall be provided.
2.10.2 The bench mark elevation and location shall be certified by a registered
public surveyor as a Texas Society of Professional Surveyors (TSPS)
Standard and Specifications for Category 8,TSPS Third Order Vertical
Control Survey. Accuracy of elevations for benchmarks shall be Texas
Society of Professional Surveyors Category 8, Third Order.
2.10.3 All bench mark locations shall be provided with ties to existing
horizontal and vertical control monuments including coordinates using
Texas State Plane Coordinate System, South Central Zone,NAD 83 for
horizontal control and NAVD 1988 datum,2001 adjustment for vertical
control.
2.10.4 Bench marks shall be constructed of a brass disc set in concrete as
approved by the City Engineer. The concrete footing for the bench mark
Page 13 of 15 Construction Plans Requirements
shall be eight inches (8") in diameter and three feet(3')deep. Concrete
shall be reinforced with two number four(2-#4)rebars.
2.10.5 The construction plans shall clearly identify the location of the bench
mark and shall include a complete description, coordinates and
elevation, with adjustment date, of the bench mark.
2.11 RESIDENTIAL LOTS AND IMPROVEMENTS
2.11.1 All residential lots shall drain to a public right-of-way directly adjoining
the lot. Drainage from a residential lot to a public right-of-way at the
rear or side of a lot may be permitted provided the drainage system has
been properly designed to accept the flow. Drainage from a residential
lot to an adjoining greenbelt or golf course shall require a public
easement for drainage purposes to be maintained by the homeowner's
association or appropriate entity. Drainage to a private easement shall
require prior approval by the City Engineer. Drainage to a private
easement shall be noted on the recorded subdivision plat. Drainage to a
Brazoria County drainage easement shall be approved by Brazoria
Drainage District No. 4.
2.11.2 A lot grading plan showing proposed minimum slab elevations shall be
included in the construction plans
2.12 FLOOD PLAIN MANAGEMENT
2.12.1 All development shall conform with the City's Flood Damage
Prevention Ordinance.
2.12.2 Amendments to the published flood maps, map revisions and all
requests for changes to the base flood elevation within Pearland city
limits shall be submitted to the City Engineer for approval. Technical
data required by the Federal Emergency Management Agency and
justification for the proposed change must be included with all requests.
All requests for changes to the base flood elevation within the City of
Pearland Extraterritorial Jurisdiction (ETJ) shall be submitted to the
City of Pearland Flood Plain Administrator for comments.
Modifications to the floodplain or floodway require a FEMA approved
Conditional Letter of Map Revision (CLOMR) prior to construction
plan approval. Upon completion of construction modifications to
floodway or floodplain will require a FEMA approved Letter of Map
Revision (LOMR).
2.12.3 All data submitted shall be prepared under the supervision of a
registered professional engineer and/or a registered public surveyor and
shall comply with all requirements of the Federal Emergency
Management Agency.
Page 14 of 15 Construction Plans Requirements
2.12.4 All development within regulatory floodplain must apply for a City
permit. Construction within the floodplain is prohibited until this permit
is approved by the City's Floodplain Administrator.
2.12.5 Per City Ordinance 532 (most current version), The Flood Damage
Prevention Ordinance, lowest floor elevation shall be minimum 1'
above base flood elevation.
2.12.6 Building floor elevation shall be 12 inches above the top of curb or 12
•
inches above 100-year floodplain.
2.12.7 Elevation Certificate is required for all new and substantial
improvement.
2.13 STORMWATER MANAGEMENT PLAN
2.13.1 All development projects irrespective of the size must develop
Stormwater Pollution Prevention Plan and meet City's latest Illicit
Discharge and Stormwater Ordinance. See Chapter 8 - Stormwater
Management for more detail.
Page 15 of 15 Construction Plans Requirements
CITY OF PEARLAND
•
CHAPTER 3
WATER SYSTEM DESIGN CRITERIA
ENGINEERING DESIGN CRITERIA MANUAL
December 2018
Page 1 of 17 Water System Design Criteria
CHAPTER 3
WATER SYSTEM DESIGN CRITERIA
3.1 GENERAL.
3.1.1 Criteria for the design of water service and water distribution lines are
herein established. All water lines constructed within the City of Pearland
or its Extraterritorial Jurisdiction(ETJ) shall follow these criteria and be in
agreement with the City of Pearland Comprehensive Plan.
3.1.2 Design, construction and sizing of all water mains and appurtenances shall
meet or exceed the requirements of the Texas Commission of
Environmental Quality (TCEQ) as per 30 TAC 290, Texas Board of
Insurance(TBI), and City of Pearland Water Master Plan/model.
3.1.3 The public water system shall not extend beyond the individual water meter.
All waterline construction in public rights-of-way up to and including
construction to the water meter shall conform to these standards.
3.1.4 Design and construction shall conform to the City of Pearland construction
details and construction specifications.
3.1.5 The"City of Pearland" for the purposes of these criteria shall consist of all
land within the city limits, and land located within the City's ETJ.
3.1.6 The final decision approving authority for the City of Pearland with respect
to the water system design criteria shall be with the City Engineer and
Public Works Department.
3.1.7 Transmission mains are defined as 20-inch and above.
3.1.8 Distribution mains are defined as 18-inch and smaller.
3.1.9 Construction and sizing of all water mains and appurtenances shall meet or
exceed the requirements of the Texas Commission on Environmental
Quality and the Texas Department of Health.
3.1.10 All proposed water distribution systems and interconnects between separate
systems and/or utility districts, shall be approved by the City of Pearland
City Engineer and Public Works Department and, if required, by the
Pearland Fire Marshal.
3.2 DESIGN REQUIREMENTS
Page 2 of 17 Water System Design Criteria
3.2.1 Obtain approval from the City Engineer for exceptions or deviations from
these requirements. Exceptions or deviations may be given on a project-by-
project basis through the variance process identified in Chapter 2.
3.2.2 Public water distribution systems shall be designed to handle the necessary
water flow based upon complete development. The necessary water flow
shall include applicable residential and non-residential uses and fire
protection flows.
3.2.3 The water system shall be designed to deliver peak-hour demand flows. The
fire flow must be available above the peak hour demand of the system and
for a duration and at the residual pressure as specified by the Fire Marshal.
3.2.4 One (1) copy in Adobe Acrobat (.pdf) format of the system hydraulic
calculations, sealed by a Texas Registered Professional Engineer, shall be
submitted with all water distribution system plans. These calculations shall
show how the water flow rates were computed,design assumptions and that
fire flow requirements are met. If the proposed water distribution system is
connecting to an existing system,verification of the flow rates and pressure
in the existing system, both before and after inclusion of the new system,
shall be provided by the design engineer and approved by the City Engineer.
3.2.5 Layout of the overall water system and of all water mains within the city
limits and extraterritorial jurisdiction shall be approved by the City
Engineer. The overall water system shall be designed to maintain adequate
pressure throughout the system. In all cases, specific water pressure and
flow analysis and study shall be required. The layout of the water mains
should provide maximum circulation of water to prevent future problems of
odor, taste, or color due to stagnant water.
3.2.6 Provide adequate circulation and place valves and fire hydrants, so that
flushing of all mains will be simplified.
3.2.7 Dead-ends shall be avoided where possible. All dead-ends shall be isolated
with a line valve,be as short as possible,and be equipped with a fire hydrant
or blow off at the end of the main as required in this Chapter.
3.2.8 Water Distribution System Materials
A. All materials used in the construction of public water distribution
systems must be in conformance with American Water Works
Association(AWWA) and NSF International guidelines.
B. Poly Vinyl Chloride (PVC) Pressure Pipe, two-inch (2") through
twelve-inch (12"), shall conform to the requirements of
ANSI/AWWA C900,current revision,Class 150 DR 18. Pipe shall
be designed and constructed in conformance with the minimum
requirements of the "Manual of Water Supply Practices", AWWA
Page 3 of 17 Water System Design Criteria
Manual No. M23. PVC pipe with the use of ductile iron fittings is
the preferred material for water line construction. The use of
ductile iron pipe is allowed as necessary.
C. Bedding and backfill shall conform to the City of Pearland Standard
Construction Details.
D. Other pipe materials may be used for construction of water mains,
when specifically approved by the City Engineer.
E. Construction of water mains shall be in accordance with approved
construction plans and the City of Pearland City Standard
Construction Details.
3.2.9 Lines:
A. Locate water lines within street rights-of-way, or appropriate utility
easement and as determined by the design model and City Engineer:
a. Six-inch interconnected/looped mains shall be a maximum
of 1500 feet long, shall be supported on both ends by an 8-
inch main or larger and shall have no more than two (2)
intermediate fire hydrants. Dead end six inch (6") mains
shall not be more than four hundred feet(400')in length and
shall terminate at a fire hydrant..
b. Except when 6-inch diameter lines are permitted under the
above criteria,all water lines shall have a minimum diameter
of 8-inches for lengths above 1500 feet, or when three(3)or
more intermediate fire hydrants are required or as
determined by the design model.
c. 10-inch diameter water line is not permitted.
d. Pipe with a min. 12-inch diameter and larger mains will be
required at locations established by the City Engineer and/or
as determined by the design model.
e. Dead-end lines:
i. Dead-end lines shall not be allowed in subdivisions
with 25 or more connections unless a looped or
interconnecting water main system is not nearby. A
non-looped system within such subdivision requires
prior approval from the Engineering Department.
ii. The design of all water distribution systems should
include the opportunity for future looping or
interconnect of any approved or proposed dead-end
line.
iii. Non-residential dead-end lines within public right-
of-way:
1. On permanent dead-end lines not serving
residential cul-de-sacs, the line shall be 8
inches in diameter and shall not exceed more
than 700 feet in length from the closest
interconnection main line and shall terminate
with a valve, reducer and fire hydrant. Line
Page 4 of 17 Water System Design Criteria
shall be restrained. Thrust blocking is not
allowed.
2. In temporary dead-end situations or if the
possibility for future extension of the water
line exists do not reduce pipe sizes
successively. Carry 8-inch diameter pipe to
the last appurtenance or the plug. Place the
last service as near as possible to the end and
install a valve,reducer and fire hydrant at the
end of the line. The maximum length of such
a line shall be 700 feet and the line shall be
restrained. Thrust blocking is not allowed
3. In unavoidable permanent dead-end
situations, reduce the sizes of pipe
successively. The last segment of line shall
be 8 inches in diameter and shall not exceed
more than 700 feet in length from the closest
interconnection main line and shall terminate
with a valve,reducer and fire hydrant. Thrust
blocking is not allowed
f. Water line placement in side lot easements shall not be
allowed except by specific approval from the City Engineer
for looping purposes. Where water line placement is
allowed, they may be required to be lined in a continuous
steel casing pipe. When such casing is required by the City,
extend the casing uninterrupted from building line to
building line. No horizontal or vertical deflections are
allowed. Construct encased water line of restrained joint
PVC pipe to prevent lateral movement. Provide and install
casing spacers and end seals. This item shall only apply to
publicly maintained lines.
B. Testing of Installed Water Lines
a. A hydrostatic ex-filtration test shall be performed on all
water lines in accordance with the requirements of TCEQ
and AWWA C600-10 (ductile iron pipe) or C605-13 (PVC
pipe) prior to being placed in service.
b. New water lines shall be thoroughly disinfected in
accordance with AWWA Standard C651 and TCEQ
requirements and then flushed and sampled prior to being
placed in service.
c. All newly installed water lines shall have to pass
bacteriological testing before being accepted for
maintenance by the City of Pearland.
Page 5 of 17 Water System Design Criteria
d. Copies of all test results shall be given to the City of
Pearland.All cost associated with the water line testing shall
be the responsibility of the developer.
C. Backfill shall be in accordance with City of Pearland Standard
Details. All backfill within public right-of-ways and public
easements shall be compacted to a minimum of ninety-five percent
(95%) of Standard Proctor Density (ASTM D2922-78 and ASTM
D3017-78),without additional moisture control, cured and tested in
accordance with ASTM C31.
D. All water located underneath and within eighteen inches (18") of
any paving shall be bedded in bedding sand and cement stabilized
sand in accordance with the Standard Construction Details. The
cement stabilized sand shall be in accordance with the following
requirements.
a. The cement shall be Portland Cement, Type I,ASTM C150.
b. The sand shall be clean, durable sand, with less than 0.5
percent clay lumps, ASTM C 142: with less than 0.5 percent
lightweight pieces, ASTM C123; with organic impurities,
ASTM C40, not showing a color darker than standard color
and a plasticity index of less than six (6) when tested in
accordance with ASTM D423 and ASTM D424.
c. Compact to ninety-five percent (95%) Standard Proctor
Density (ASTM D2922-78 and ASTM D3017-78) in
maximum loose lifts of eight inches (8") thick. Actual
testing shall be required as deemed necessary by the City of
Pearland.
d. The cement-sand mixture shall consist of at least 1.5 sacks
of cement per ton of sand. The cement-sand mixture shall
have a minimum unconfined compressive strength of one
hundred pounds per square inch(100 psi) in forty-eight(48)
hours,when compacted to a minimum of ninety-five percent
(95%) of Standard Proctor Density (ASTM D2922-78 and
ASTM D3017-78), without additional moisture control,
cured and tested in accordance with ASTM C31.
E. Water lines outside of paving shall be bedded in accordance with the
Standard Construction Details.
F. Bedding shall be compacted to ninety-five percent (95%) Standard
Proctor Density six-inches (6") over pipe prior to backfilling the
trench. In water bearing sand, washed shell or other approved
granular material will be required with geo-textile fabric wrap as
shown in the Standard Construction Details. When water bearing
sands are encountered, the City of Pearland shall be notified
immediately.
Page 6 of 17 Water System Design Criteria
G. Within 90-days of the end of the two-year warranty period the
developer/contractor shall conduct a scouring of the line though
"pigging"the lines. This will be coordinated with the City Engineer
and Public Works Department for this work. Costs to conduct this
cleaning shall be borne by the developer/contractor.
3.2.10 Location
A. Boulevard streets: If approved, public water lines may be located
within the esplanade. Water lines should be located as near the
centerline as possible to avoid conflict with future pavement
widening. The lines should be located in the street right-of-way to
avoid conflict with future pavement widening.
B. Locations within an easement: Locate water lines in the center of a
20-foot minimum width dedicated water line easement. For location
within side lot easements, the minimum easement width shall also
be 20 feet. Should the line be installed as per Section 3.2.9.A.f the
easement width may be reduced to 10-foot minimum width. The
City Engineer may require a wider easement if the line is to be
buried more than 8 feet deep from natural ground surface at any
point in the easement. Obtain approval from the City of Pearland
for lines to be located in smaller or multi-use easements.
C. When a water line is placed parallel to but not crossing any other
proposed or existing utility line, other than a sanitary sewer, the
water line shall have a minimum of 4 feet horizontal clearance from
the outside wall of the existing utility to the outside wall of the
proposed waterline. Any proposed deviation from these criteria
must first be approved by the Engineering Department.
D. A minimum distance of 2 feet shall be maintained from the right-of-
way or easement line to the outside edge of the water line.
3.2.11 Depth of Cover(See Table 3.1)
A. Provide the minimum depths of cover shown in Table 3.1 from the
top of natural ground behind the curb for curb-and-gutter streets, or
from the lowest elevation of the nearby ditch bottom for roadside
ditch street sections whichever is applicable unless a variation is
granted by the Engineering Department.
B. Whenever possible, changes in grade or alignment to clear utilities
or underground features should be accomplished by deflecting pipe
joints. The maximum designed deflection shall be '/2 of the
Page 7 of 17 Water System Design Criteria
manufacturer's allowable deflection. The vertical realignment shall
be restrained in each direction per restraint requirements and be
constructed with mechanical joint fittings and restraints. Any bell
joints located in the vertical realignment shall also be restrained.
C. If a depth greater than 8 feet is proposed,all joints of PVC pipe shall
be mechanically restrained. All fittings shall be restrained. Where
conflicts are encountered with utilities or other underground
facilities, the depth of cover may be reduced to 2 feet from top of
curb.
Table 3.1
DEPTH OF COVER FOR WATER LINES
SIZE OF LINE DEPTH OF COVER*
TOP-OF-CURB OPEN-DITCH
8-INCH &6-INCH 4 FEET 5 FEET below ultimate
flowline
12-INCH&LARGER 5 FEET 5 FEET below ultimate
flowline
*When crossing easements whose owning or governing agency has stricter depth of cover
criteria than that shown in Table 3.1, the stricter of the two shall apply. Where other
agencies have review authority or jurisdiction and have different depth of cover
requirements, the stricter of the two shall apply.
3.2.12 Appurtenances
A. Do not place appurtenances in pavement when the appurtenance
would be covered in whole or in part by pavement. When approved
by the City, gate valves may be placed in sidewalks or paved
roadways provided that the top of the valve box is flush with the
finished pavement.
B. All water system valves shall conform with AWWA standards and
shall include:
a. Cast iron valve boxes are required on all valves.
b. All valves shall be sized to equal the size of the water main.
C. Valves
a. Spacing—set at maximum distances along the water line as
follows:
i. Distribution— 1000 feet
ii. Transmission—2000 feet
Page 8 of 17 Water System Design Criteria
iii. The total number of valves at any water line
intersection shall equal the total number of lines
leading out from the intersection point.
iv. Refer to standard specifications for tapping sleeve
&valve.
b. Location
i. Valves must be located at street intersections along
the street right-of-way lines projected across the
water line where possible. Tapping sleeve and
valves are excluded from this requirement.
ii. Isolate fire hydrants and flushing valves from the
service main with a valve located on the fire hydrant
or flushing valve lead at the main line connection.
This valve should not be located in the slope or
flowline of roadside ditches.
iii. Intermediate valves, not located on the projection of
the right-of-way line, shall be located on the water
line 5 feet from a fire hydrant but shall not be set in
a driveway.
iv. Locate valves a minimum of 10 feet horizontally
away (either direction) from any sanitary sewer
crossing.
v. Valves located near reducers shall be located on the
larger diameter pipe.
vi. All water mains shall be valved within the street
right-of-way.
vii. Valves shall not be placed under or within 2 feet of
ultimate pavement,when it is known that the street
will be widened in the future,without prior approval
of the Engineering Department.
c. Valve Type
i. All valves shall be resilient seated Gate Valve,
AWWA C509, counterclockwise opening with
mechanical joints(MJ) or flange by MJ connections.
Valves shall have a complete epoxy coating on all
iron parts in the valve interior and exterior to
eliminate corrosion.
ii. Butterfly valves are not allowed in the distribution
system.
iii. Valves shall be approved by the City and shall be
listed on the Approved Products List.
D. Fire Hydrants
Page 9 of 17 Water System Design Criteria
a. Fire hydrants shall have three-way nozzle arrangement, five
and one-quarter-inch(5-1/4") compression type main valve,
mechanical joint boot, and conform to the requirements of
AWWA C502. The pumper nozzle shall be equipped with a
five-inch (5") Storz locking connection that is factory
installed.Hydrants shall be factory painted.Field painting of
the hydrants after installation is not allowed other than
touch-up. Approved fire hydrants shall be listed on the
Approved Products List.
b. The body of the fire hydrant shall be factory painted Safety
Blue (Code No 225A120) two part Polyurethane Enamel.
All paints shall conform to the City of Pearland Fire Hydrant
Color Code. Fire hydrants shall be color coded on the fire
hydrant bonnet and caps based upon mainline size. The
paint utilized shall be a two part Polyurethane Enamel or
approved equal and installed in accordance with the
manufacturer's instructions. The color code shall be as
follows:
Color Water Main Diameter Polyurethane Enamel
(in.)
White 6" Glossy White Code No
225A120
Orange g„ Safety Orange Code No
225A122
Green 12" John Deere Green Code
No 225A133
Yellow 16"to 20" John Deere Yellow
Code No 225A138
Red 22"and larger Safety Red Code No
225A123
c. All fire hydrants shall be installed so that the steamer
connection will face the fire lane or street or as directed by
the Fire Marshall.
d. A Blue Stimsonite, Fire-Lite reflector model 88-SSA (or
approved equal) shall be placed 12 inches (12") from the
centerline of the street, offset towards the fire hydrant. At
intersections, reflectors shall be placed on both roadways
opposite fire hydrant.
e. Spacing
i. Single family residential development — 500 foot
maximum spacing or as designated by the Fire
Marshal.
ii. All other development — no less than 300 foot
spacing.
Page 10 of 17 Water System Design Criteria
f. Location in or along street right-of-way
i. Locate fire hydrants primarily at or near street
intersections.
ii. Locate fire hydrants at the end of a curb radius of a
street intersection, 3 feet behind back of curb or
projected future curb in a curb & gutter road
construction application.
iii. On cul-de-sacs, place fire hydrant in straight section
to avoid conflict with placement of the sidewalk.
iv. On streets with roadside ditches, set the fire hydrants
within 5 feet of rights-of-way lines. Fire hydrant lead
valves should not be located in the slopes or flow
lines of ditches.
v. Set fire hydrants not located at intersections or block
corners at mid-lot or on lot lines, as extended to
pavement, when located between right-of-way
intersections. These locations may be adjusted 5 feet
either way to avoid driveways or obstructions. In
either case, do not locate fire hydrants closer than 5
feet from driveways.
vi. Provide fire protection on both sides of Major
Thoroughfare and Collector roads.
vii. Fire hydrants are not allowed in esplanades of streets.
viii. On all Texas Department Transportation (TxDOT)
rights-of-way, set the fire hydrants and flushing
valve set-backs from the edge of right-of-way shall
adhere to TxDOT criteria.
g. Location of fire hydrants or flushing valves outside street
rights-of-way and in public easements:
i. City review and approval is required for all submitted
locations of fire hydrants and flushing valves in all
developments within the City of Pearland and its
ETJ.
ii. Locate fire hydrant and flushing valves in protected,
easily accessible areas behind curb lines.
iii. For fire hydrants or flushing valves that are located
adjacent to water lines constructed in 10 foot wide
water line easements, the fire hydrant or flushing
valve shall be centered in a minimum 15 foot by 15
foot separate easement.
iv. For non-residential developments in the City of
Pearland,provide isolation valves at each end of fire
loops requiring on-site fire hydrants.
h. Fire hydrant leads shall be designed to have a minimum 4
foot bury where possible. Bends may be used on the fire
Page 11 of 17 Water System Design Criteria
hydrant branch to maintain a 4 foot bury or a 3 foot back of
curb set-back.
Do not install fire hydrants within 10 feet vertically or
horizontally of sanitary sewers and force mains.
j. The fire hydrant supply line from the public water main to
the fire hydrant shall be constructed of Ductile Iron Pipe.
PVC is not allowed.
k. The depth of bury for all fire hydrants shall be established
such that the manufacturer bury line on the fire hydrant is
installed at the ground line at each location or at the finished
ground after pavement construction.
1. Fire hydrants shall not be installed within nine feet(9') of a
sanitary sewer system under any conditions.
m. Fire hydrants that are to be designated as private shall have
a factory coated body color of red.The caps and bonnet shall
be coated as per this Chapter. These fire hydrants will be
owned and maintained by the property owner/entity. The
valve for the fire hydrant line shall be located at the public
water main.
E. Fittings
a. Fittings shall be Ductile-Iron Compact Fittings Three-Inch
(3") to Twelve-Inch (12"), AWWA C153/A21.53.84,
conforming to the minimum requirements of"Gray-Iron and
Ductile-Iron Fittings, Twelve-Inch (12") through Forty-
Eight-Inch (48"), for Water and Other Liquids", AWWA
C153 (ANSI 21.10), current revision. Fittings shall be
furnished with epoxy or cement mortar lined,AWWA C104
(ANSI A21.4).
b. All fittings shall be identified and described on the
construction plans.
c. Fittings are not permitted in fire hydrangea leads, except as
specifically approved by the City Engineer,
d. Water main fittings shall be mechanical joint.
e. All water main pipe joints shall be push-on joints. Only
flanged joints shall be used for above ground waterline
installations or at above ground valve locations.
f Polyethylene tube encasement shall conform with the
minimum requirements of "Polyethylene Encasement for
Gray and Ductile Cast-Iron Piping for Water and Other
Liquids", ANSI/AWWA C105, current revision. Soils
within the project shall be tested in accordance with
Appendix A of ANSI/AWWA C105 to adequately
determine the requirements for encasement.
g. All underground bolts and nuts shall be 316 stainless steel.
F. Ductile Iron Pipe
Page 12 of 17 Water System Design Criteria
a. Use of ductile iron pipe shall be with prior approval of the
City Engineer and Public Works Department..
3.2.13 Water Meter Service
A. All water meters 1 or 2 inches shall be installed by the City of
Pearland on custom home residential properties. All water meters
in subdivision developments shall be installed by City personnel.
B. Vaulted water meter installation shall be undertaken by private
contractors with prior approval from the Engineering Department.
C. Stub outs for future water service are not allowed except where part
of a preapproved master plan, site plan development plan or tract
development plan.
D. Minimum size water service line and fittings shall be 5/8 inch meter
with 3/4 inch stop at the meter for any single connection for
residential homes. The Chief Building Official and Inspection
Services should be consulted to ensure the proper sized meter is
selected for any proposed service.
E. Water service leads from the water main to the water meter shall be
placed at a minimum 4 foot below fmal paving elevations.
F. Meter boxes shall be located just within the public right-of-way.
Location of meters in the ditch of open ditch streets shall be avoided.
Meter boxes shall be installed no more than 2 inches above fmal
natural ground.
G. Back-flow prevention devices shall be installed in line on the private
water meter service line on all commercial developments, irrigation
metered service, and shall be installed in all applications where the
City of Pearland's Plumbing Code and its latest revision so requires.
3.2.14 Water Line Crossings within the City of Pearland
A. Public and private utility crossings other than sanitary sewer: Where
a water line crosses another utility other than a sanitary sewer, a
minimum of 6 inches of clearance must be maintained between the
outside wall of the water line and the outside wall of the utility.
B. Stream or ditch crossings
a. Elevated crossings
Page 13 of 17 Water System Design Criteria
i. Water lines shall be welded steel pipe and shall
extend a minimum of 15 feet beyond the last bend or
to the right of way line,whichever is greater.
ii. Elevated crossings are preferred to underground
crossings.
iii. Use a separate elevated supporting structure for 12
inch and larger water lines. Locate structures a
minimum of 10 feet from any existing or proposed
structures.
1. Adequate structural capacity shall have been
calculated and provided for including
considerations for pipe deflection and all
applicable loading.
2. Clearance for maintenance purposes above
bent cap elevation shall be provided where
elevated water lines are to be run under
bridges.
iv. When approved by the Engineering Department,
bridge attachments for elevated water line crossings
may be made instead of separately supported
crossings. Designer to provide support documents
that bridge was designed for such load or provide
analysis signed and sealed by a professional engineer
that bridge can support such load.
v. Design elevated crossings with the elevation of the
bottom of the water line 2 feet above the 100-year
floodplain elevation
vi. Create a high point in the elevated stream or ditch
crossing and provide an air release valve at that
highest point of the water line.
vii. Provide sufficient span length to accommodate the
cross section of future widening of the stream or
ditch to ultimate cross section.
viii. Base the columns' support designs on soil capacity,
spacing, loading, and all pertinent structural
requirements.
ix. Spacing of supports shall consider effect of support
on channel hydraulics and be subject to city
approval.
x. Provide pedestrian pipe guards on elevated
crossings.
b. Underground Crossings
(1) Provide a minimum 5 foot clearance from the top of
the pipeline to the ultimate flow line of the ditch.
Page 14 of 17 Water System Design Criteria
(2) Provide sufficient length to exceed the ultimate
future development of the stream or ditch.
(3) Water lines shall be C-900 PVC, HDPE, Fusible
PVC or ductile iron pipe (if approved by the
Engineering Department) and shall extend a
minimum of 15 feet beyond the last bend or to the
right of way line,whichever is greater.
(4) Where other agencies have review authority or
jurisdiction and have different underground crossing
requirements, the stricter of the two shall apply.
C. State Highway and County Road Crossings
a. Extend carrier pipe from right-of-way to right-of-way.
b. The approval of the design by the appropriate governmental
agency shall be demonstrated to the City Engineer before
plans will be approved.
c. Where additional right-of-way has been acquired for future
widening, the casing shall extend 5 feet beyond each right-
of-way line.
D. Railroad Crossings
a. For mainline and spur line railroad crossings, the water line
shall meet the requirements of the governing agency and
such requirements shall be followed from 5 feet beyond each
right-of-way line and across the right-of-way itself. Any
deviation must be approved by the railroad companies. The
approval of the design by the appropriate governing agency
shall be obtained and submitted to the City Engineer before
plans will be approved.
b. Where there is no railroad but a railroad owned easement or
right-of-way,as a minimum extend a steel casing from right-
of-way to right-of-way line.
c. The approval of the design concept by the railroad involved
must be obtained and submitted to the City Engineer before
plans will be approved.
E. Additional Requirements
a. Isolate water lines from casing with spacers and supports.
b. The carrier pipeline shall extend a minimum of 1-foot
beyond the end of the casing to allow flanged joints to be
constructed if necessary.
F. Oil and Gas Pipeline Crossings
Page 15 of 17 Water System Design Criteria
Use PVC pipe when crossing a non-service transmission pipeline
regardless of depth. Designer is required to meet with the City
Engineer to discuss possible encasement for the PVC water main.
All non-service transmission pipeline crossings must have the
approval of the company whose lines are being crossed. Maintain a
minimum 2 foot vertical separation between the pipeline and the
water line.
3.2.15 Auger Construction: Use the following general criteria for establishing
auger, bore and jack, or microtunneling sections when site conditions
require their use:
A. Improved streets — Use auger or microtunneling construction to
cross a street regardless of surface. Auger or microtunneling length
shall be computed as roadway width at the proposed bore location
plus a minimum of 10 feet to either side of roadway.
B. Driveways — Use auger or microtunneling construction to cross
improved driveways. Bore and jack,auger or microtunneling length
shall be a minimum of the driveway's width.
3.2.16 Circulation and Flushing for Water Quality: The layout of the water
distribution system shall provide for maximum circulation of water.
A. Provide a source of fresh water at each end or at multiple points of
a subdivision or development. Provide ways to create circulation
and place valves and fire hydrants to allow simple flushing of lines.
3.2.17 New Water Lines Constructed Near Sanitary Sewers and Force Mains and
Manholes
A. Water mains shall be designed and located to conform to regulations
of the Texas Commission on Environmental Quality.
B. For water mains crossing an existing or proposed sanitary sewer or
force main,the following clearances shall be provided for protection
from contamination. The minimum clearances will be approved
only when justified and field conditions so dictate. The latest edition
of"Rules and Regulations for Public Water Systems", of the Texas
Commission on Environmental Quality, shall be followed for
minimum criteria and instructions for water line crossings
3.3 QUALITY ASSURANCE
3.3.1 Prepare calculations and drawings prepared under the supervision of a
Texas Professional Engineer trained and licensed under the disciplines
required by the nature of the drawings. The final design drawings, must be
Page 16 of 17 Water System Design Criteria
sealed, signed and dated by the Professional Engineer responsible for
development of the drawings.
3.3.2 For Elevated Stream and Ditch Crossings: Prepare design calculations for
support columns and column spacing.
3.4 ADDITIONAL STANDARDS
3.4.1 All existing developed areas shall be restored to original condition after
construction.
3.4.2 Proper barricading and signage, conforming to the Texas Manual of
Uniform Traffic Control Devices' latest edition, shall be required on all
projects. Adequate signage for vehicular and pedestrian traffic shall be
installed. A traffic control plan shall be submitted to the City of Pearland
and approved by the City Engineer for all streets open to travel by the
public.
3.4.3 A continuous trace wire, such as a solid 14-guage copper wire with blue
shielding or approved equal, shall be affixed to the top of the new water
main prior to bury. Trace wire shall be connected to all water meter angle
stops, fire hydrants, and valve box risers. Wire splices shall be completed
using approved, mechanical splice kits. Soldered connections are not
permitted. A continuity test shall be completed prior to acceptance.
3.4.4 As an option to trace wire the use of locator "ball markers" that are color
coded for the water main can be used. Spacing to be at the manufacturer's
recommendation. This option will require City Engineer and Public Works
Department Approval.
3.5 EXTRA TERRITORIAL JURISDICTION
The criteria herein described in this chapter shall be applicable to all water main
and appurtenance construction and all devices thereunto related within the City of
Pearland and required for projects located within the ETJ. For those projects
located in the ETJ, the City of Pearland will review public improvement
construction drawings for conformance with the City's Standards.
Page 17 of 17 Water System Design Criteria
CITY OF PEARLAND
CHAPTER 4
SANITARY SEWER DESIGN CRITERIA
ENGINEERING DESIGN CRITERIA MANUAL
December 2018
Page 1 of 31 Sanitary Sewer Design Criteria
CHAPTER 4
SANITARY SEWER DESIGN REQUIREMENTS
4.1 GENERAL
4.1.1 This chapter addresses the design of the sanitary sewer systems to be located
within the public right-of-way or a dedicated public easement and the extra-
territorial jurisdiction of the City of Pearland. Sanitary sewers located on
private property, that are not in a dedicated public easement, shall not be
considered part of the publicly maintained sanitary sewer system.
4.1.2 Construction plans for private improvements, within public right-of-ways
and public easements that connect to or affect the public infrastructure shall
be approved by the City of Pearland subject to the requirements of this
manual and are subject to review and approval using the process defined in
this manual.
4.1.3 Construction and sizing of all sanitary sewer mains and appurtenances shall
meet or exceed the requirements of the Texas Commission on
Environmental Quality and the Texas Department of Health.
4.1.4 Sanitary sewer service shall be extended to all building sites prior to
development. Septic systems are not allowed, except as specifically
approved by the City Engineer.
4.1.5 The public sanitary sewer system shall be defined as all sewers, including
stacks and service leads that are located in public easements or street rights-
of-way, and that are installed in accordance with these Standards. The
public sanitary sewer system shall not extend beyond the service
connection. All public construction shall conform to the requirements of
this manual. All private construction beyond the service connection shall
conform to the requirements of the City of Pearland adopted Plumbing
Code.
4.1.6 On a case-by-case basis the City of Pearland reserves the right to allow
deviations from these design criteria where necessary. See Chapter 1 for
procedures to apply for variances to these design criteria. These design
criteria are not intended to cover repairs to pre-existing facilities especially
when such repair work is performed by City of Pearland personnel/forces.
These criteria are not intended to cover existing sanitary sewer facilities
located in alleys or other areas that do not conform to these criteria.
4.2 DEFINITIONS
Page 2 of 31 Sanitary Sewer Design Criteria
4.2.1 Public Sanitary Sewer - All sewers that are maintained by the City of
Pearland and located in public easements or street rights-of-way, pre-
existing sanitary sewer lines that are serving the public at the time of the
adoption of these regulations, and new sanitary sewers that are installed in
accordance with these standards.
4.2.2 Sanitary Sewer Main—A sewer which receives the flow from one or more
lateral sewers.
4.2.3 Lateral Sewer—A sewer running laterally down a street, alley or easement
which receives flow from abutting property.
4.2.4 Service Lead—A sewer which branches off of a public sewer and extends
to the limits of the public right-of-way. It shall be construed as having
reference to a public sewer branching off from a main or lateral sewer to
serve one or more houses, single family lots, or other types of small land
tracts situated in the same block, but not directly adjacent to the main or
lateral sewer. A service lead shall never exceed 100 feet in perpendicular
length from the intersecting sewer main or lateral. If the sewer is designed
to serve more than two houses, or the equivalent of two single family
residences along a street, a lateral sewer as defined above shall be
constructed.
4.2.5 Septic Systems - Septic systems are not allowed, except as specifically
approved by the City Engineer
4.3 DESIGN REQUIREMENTS
4.3.1 Drawings to be Furnished
A. Before any Public Sanitary Sewer is constructed and before the City will
approve any proposed sanitary sewer for construction, plan-and-profile
sheets of the proposed sanitary sewer shall be prepared and submitted
to the City Engineer for approval.
B. Drawings shall include at a minimum layout sheets, plan-and-profile
sheets, and details sheets for special items.
C. Sanitary sewers shall conform to the City's Wastewater Master
Plan/model for orderly expansion of the system.
D. Sanitary sewer systems shall be designed to handle the necessary flow
based upon complete development. The necessary flow shall include
applicable residential and non-residential average daily flows and shall
Page 3 of 31 Sanitary Sewer Design Criteria
include a minimum peak design flow of 4 times the average daily flows.
Sanitary sewer systems within the City of Pearland's jurisdiction shall
allow for orderly expansion of the system and shall conform to the
Wastewater Master Plan for the City of Pearland.
E. The average day flow for the design of sanitary sewers shall be based
on a minimum set by the Texas Commission on Environmental Quality
in gallons per day per single-family connection for residential areas.
Commercial, industrial, and office areas shall be designed for an
average day flow that can be anticipated from contributing area.
F. One copy of the system hydraulic calculations, sealed by a Texas
Registered Professional Engineer,shall be provided electronically(PDF
format) with all sanitary sewer system plans. These calculations shall
show how the sanitary flow rates were computed; design assumptions
and that Texas Commission on Environmental Quality requirements are
met. If the proposed sanitary sewer system is connecting to an existing
system,verification of the availability of capacity in the existing system,
after inclusion of the new system, shall be provided by the design
engineer and approved by the City.
G. All gravity sewers will be designed to accommodate the peak flow from
the contributing service area. The peak flow will be computed using the
appropriate peaking factor,F,multiplied by the average day flow for the
contributing area. For nonresidential areas, the peak flow should
include consideration of flow characteristics from the anticipated
development. The minimum allowable values for the design peak factor
are:
a. In all cases, the design peaking factor, F, shall meet or exceed
the values as follows
1) An equivalent population less than 5,000 persons:
F=4
2) An equivalent population greater than or equal to 5,000
persons:
F=(14/(3.316+P05))+ 1.5
P=equivalent population in thousands
b. Sewers larger than eighteen-inch (18") may be sized using a
peaking factor of less than four (4) with approval of the City
Engineer.
H. Additional consideration of peak flow shall be given for design of
pumping stations. The impact of pumping stations on the upstream and
downstream sanitary sewer system shall be evaluated. The peak flow
for design of a pumping station shall be based on the actual flow into
the station. A reduced peak flow,based on the peaking factor presented
above, may be used for design of larger pumping stations provided a
Page 4 of 31 Sanitary Sewer Design Criteria
detailed hydraulic analysis is performed on the sanitary sewer system.
Specific approval by the City Engineer shall be required prior to use of
a reduced peak flow for the design of a pumping station and related
sanitary sewer system.
I. The minimum size allowable public sewer shall be eight-inch (8").
Public sanitary sewers are not allowed in back lot/rear yard easements.
J. The minimum size residential sanitary sewer service lead shall be four-
inch(4") and shall serve only one residential lot. A single six-inch(6")
sanitary sewer service lead shall not serve more than two(2)residential
services.
K. Commercial sewer service leads shall be six-inch(6")pipe or larger and
shall not serve more than one(1)commercial connection.
L. A cleanout shall be placed at the property line.
M. All elevations shall be shown to the nearest one-hundredth of a foot
(0.01').
N. All stationing shall be based on centerline of street right-of-way
stations.In utility easements where both sanitary sewer and storm sewer
piping are constructed and laid in parallel trenches, stationing shall be
based on centerline of storm sewer piping.
0. All mains to be installed under an existing roadway should be installed
by bore unless otherwise approved by the City Engineer.
4.3.2 Details to be Shown on Drawings:
A. The construction drawings shall show at a minimum the exact
location of the proposed sanitary sewer in the right-of-way,alley,or
dedicated easement with respect to the edge of the particular right-
of-way, survey base line, any nearby utilities, 100-year floodplain
elevation within the project area, major landscaping (existing and
future), and other structures (above ground and below ground)
within the construction site.
B. No trees or landscaping with invasive root structures shall be placed
in the sanitary sewer easements
4.3.3 Sanitary Sewer Mains and Lateral Sewers Layout and Placement
Page 5 of 31 Sanitary Sewer Design Criteria
A. All sanitary sewer systems shall be designed in conformance with
the requirements of the Texas Commission on Environmental
Quality and other applicable standards.
B. Sanitary sewers shall be identified by number, letter, or other
identification as shown on the sanitary sewer layout sheet and
manholes shall be identified by letter or number.
C. Sanitary sewers in curved easements,easements defined by property
lines,and combined easements containing other public utilities must
be shown in both plan and profile views.
D. The profile shall show other underground and surface utilities and
facilities, both in parallel and at crossings; the size, grade, and type
of pipe of the proposed line, the elevations of the proposed line to
the hundredths of a foot at manholes, changes of grade and clean
outs where allowed; and the proposed finished grade over the sewer
with elevations. Where proposed fill or cut is contemplated, the
proposed new natural ground line should be shown as a separate line
from the pre-existing natural ground line. Bedding and backfill shall
comply with City of Pearland standard specifications and standard
details.
E. The construction drawings shall show the existing natural ground
line at either the right-of-way or edge of easement, in addition to
centerline of the pipe, when the proposed sanitary sewer is to be
placed:
a. Between the existing pavement and the right-of-way line.
F. Between existing pavement and an existing or proposed easement.
When a sanitary sewer is located under existing pavement, then the
finished elevations of the pavement shall be shown on the
construction drawings.
G. Sanitary sewers shall be laid in a straight alignment, manhole-to-
manhole.No curvilinear bends are allowed.
H. All connections to the public sewer system shall be approved by the
Department of Public Works prior to construction. A representative
of the utility system shall inspect actual connections to the public
sewer system.
4.3.4 Plan and Profile Required for Sewer Mains
A. Sanitary sewer overall layout sheets for single family residential
subdivisions should use a standard engineering scale large enough
Page 6 of 31 Sanitary Sewer Design Criteria
to show the entire project on one and no more than two standard
22"x34" sheets. In all cases, the following information must be
shown on the layout:
a. All easements containing or buffering sanitary sewers. These
corresponding recordation information including but not limited
to the corresponding file number for the easement.
b. Sanitary sewer sizes are shown at points of size change and
between all manholes.
c. All manhole locations.
d. The sanitary sewer alignment shall accurately reflect in the plan
and profile sheets the location of the sanitary sewer as shown on
the detailed plan view.Alignment shall be stationed with 100-ft.
stations.
e. Service leads that cross street pavement or serve adjacent
property are to be shown on the overall layout.
f. The number, size, and layout of the lots depicted on both the
overall sanitary sewer layout sheet and the individual plan-and-
profile sheets shall match the number and size of the lots
depicted on the final plat after recordation.
g. The direction of flow for existing and proposed sanitary sewers
shall be shown on the overall sanitary sewer layout sheet.
h. The location of the proposed sanitary sewer within either the
public right-of-way or,a dedicated easement.
i. The overall sanitary sewer layout sheet shall show the area, in
acres or in number of lots plus any acreage outside the project
area, which the proposed sewer is designed to serve. Include a
vicinity map which references the project or lots to nearby major
thoroughfares.
B. Commercial sanitary sewer layouts shall follow the same overall
layout sheet format.
C. Horizontal and vertical scales for the detailed plan-and-profile views
shall be confined to standard engineering scales.
D. The plan view shall show, at a minimum, all of the following
information for the project area:
a. Topographical features.
b. Stationing for the proposed sewers.
c. All existing utilities including gas,power,telephone,fiber optic,
cable etc.
d. Any significant landscaping or other structures which might
impact construction or construction-related activities.
e. The width and type of existing and/or proposed easements.
Page 7 of 31 Sanitary Sewer Design Criteria
f. Proposed service leads.
g. The limits of any proposed bore and jack,microtunnel, or auger
operations.
h. Locations where pressure pipe is to be installed for water line
crossings.
i. The proposed sanitary sewer with pipe diameter,length,material
type, and grade clearly labeled.
E. The profile view shall show, at a minimum, all of the following
information for the project area:
a. Underground and surface utilities/facilities which are either
parallel to the proposed sanitary sewer or cross the proposed
sanitary sewer within the construction site.
b. The proposed sanitary sewer's diameter, grade, length, and
material type for each section between manholes. This shall be
labeled on every applicable page and identified as"proposed."
c. The flowline elevation and centerline station for every sanitary
sewer at every manhole.
d. The top of rim elevation of affected existing and proposed
manholes.
e. The flowline elevation and centerline station at each sheet break.
f. The type of pipe bedding and backfill shall comply with City of
Pearland standard specifications and standard details.
g. The finished grade for proposed and existing pavement. Where
cut and fill are proposed, the proposed new natural ground line
should be shown as a separate line from the existing natural
ground line.
h. The existing natural ground line at the centerline of the sanitary
sewer when a sewer is to be placed between the edge of
pavement and the public right-of-way. In the cases where
roadside ditches exist, the centerline elevations of the roadside
ditch shall be shown.
i. The existing ground line at the centerline of the proposed
sanitary sewer where a sanitary sewer is to be placed within an
existing easement. Show any proposed cut and fill as described
above.
j. The limits of any proposed bore and jack,microtunnel, or auger
operations.
k. Locations and limits of where pressure pipe is to be installed for
water line crossings.
1. The location of special backfill and any proposed stacks shall be
identified by stations indicated on the design plans.
m. Avoid vertical breaks in profiles. Use alternate scale for all
profile sheets if all of proposed sanitary sewer cannot be shown
Page 8 of 31 Sanitary Sewer Design Criteria
on any one profile section for the station run indicated in plan
view for that sheet.
F. All construction drawings for new sanitary sewers shall show the
proposed location, by stations and offsets, of all service leads, and
service connection risers.
4.3.5 Service Lead Construction for Residential and Commercial Developments
A. Space the location of service leads so as to limit the number of
service lead taps to the lateral sewer or sewer main. Service leads
should be spaced at every other property line between two adjoining
residential lots unless there is an odd number of lots. The City
reserves the right to direct the engineer to relocate any proposed
service lead upon reviewing any submitted plans. A single 6-inch
service lead located at the property line between two adjoining
residential lots would serve two single-family residences with a wye
placed at the end of the service lead with a cleanout. The wyes shall
be located at the private property line.
a. Near side double sewer service leads shall not exceed 5 feet in
length, shall terminate at the property line with a cleanout, and
shall be located within the public right-of-way or dedicated
easement.
b. In cases where the sanitary trunk main is farther than 5 feet from
edge of the right-of-way, a single 6-inch service shall be run
from the sewer main to the edge of the right-of-way whereupon
a wye,with a cleanout,shall be placed at the end of service lead,
if 2 lots or parcels are to be served. This shall apply to residential
sanitary service leads and not to commercial service taps.
B. Any far side service lead of more than 100 feet perpendicular to the
street right-of-way shall, at the City's discretion, be treated as a
lateral sewer.
C. Service leads for single-family developments shall connect to the
main line.
D. Commercial or industrial service leads expected to discharge more
than 5,000 gallons-per-day shall discharge directly into a proposed
or existing sanitary sewer manhole at the flow line without a drop
manhole. Any variance from this requirement shall have prior
approval from the City Engineer.
a. Service leads shall be provided to serve each lot or parcel within
a proposed residential, commercial or industrial development.
Page 9 of 31 Sanitary Sewer Design Criteria
The detail for a typical near-side and far-side service leads shall
be included with the construction drawings.
b. Service leads shall be a minimum of 6 inches in diameter where
two or more lots or parcels are served. If the perpendicular
length of a service lead exceeds 100 feet,the minimum diameter
shall be 6 inches and a manhole shall be utilized for connection
to the public sewer. The use of 8 inch leads may, at the
discretion of the City, be reviewed upon submittal of the
construction drawings as a lateral sewer line.
c. In such cases where a service lead is proposed to run diagonally
across the street, prior approval from the City Engineer must
be obtained.
d. Service leads with a diameter of 6 inches shall utilize full body
fittings be they extruded or factory-fabricated for connection to
a proposed public sewer or an approved saddle-type connector
for connection to an existing public sewer.
e. For residential and commercial developments connection shall
be full-body tee.
f. The service lead shall be placed so as to minimize the use of
bends as site conditions permit.
g. For existing residential lots (which are not served in accordance
with these guidelines)that need a service lead, if the distance to
the nearest existing sanitary sewer is less than 60 feet and is not
the long side of the sewer main,the service lead may be a 4 inch
line if only one lot or parcel is to be served. Commercial and
industrial lots and parcels shall have a minimum 6 inch line
under the same conditions.
h. The location where the service lead or its wye meets the property
line shall be shown on the plans and as-builts,and marked in the
field as shown on the standard details. There shall be a riser
placed where the service lead meets the property line so that the
service lead stub-out can be recovered at the time that the
connection to the service lead is made.
i. All service leads shall be installed at the time of the construction
of the sanitary sewer in new residential subdivisions.
4.3.6 General Requirements
A. A licensed plumber shall be responsible for connecting private
residential sanitary sewer service to the public sanitary sewer system,to
wyes and/or tees or to lateral sewers as indicated on the plans. Said
licensed plumber shall be responsible for a properly installed and
watertight private residential service connection.
B. Commercial service connections to the public sanitary sewer with more
than 5,000 gallons per day flow, shall be made at manholes. Service
Page 10 of 31 Sanitary Sewer Design Criteria
connection at a concrete manhole should have a rubber boot that is cast
into manhole or service connection should be cored. If cored, opening
must be secured with"Linkseal",grouted and manhole coating shall be
repaired.
C. All materials used in the construction of sanitary sewer systems shall be
in conformance with the City of Pearland Approved Products List and
the requirements of the Texas Commission on Environmental Quality.
Sewers shall be designed to meet or exceed the pipe manufacturer's
recommendations for depth.
D. Solvent welded sanitary sewer joints are not an acceptable joining
method for PVC piping materials. Use of rubber gasketed bell and
spigot sanitary sewer joints shall be mandatory.
E. Sanitary sewers fifteen inches (15") or less in diameter and installed at
depths of sixteen feet (16') or less to invert shall be constructed
conforming to ASTM specification D 3034 SDR-26(115psi)color shall
be green and shall meet ASTM specifications D 3212 for pipe joined
with rubber gaskets conforming to ASTM F477. Bell (female) ends of
pipe shall be installed on upstream side with spigot(male)ends oriented
downstream.
F. All sanitary sewers greater than eighteen inches (18") in diameter and
less than twenty-seven inches (27") in diameter and installed at depths
of eighteen feet (18') or less to invert shall be constructed conforming
to ASTM specification F 679 SDR-26 (115psi)color shall be green and
shall meet ASTM specifications D 3212 for pipe joined with rubber
gaskets conforming to ASTM F477. Bell (female) ends of pipe shall be
installed on upstream side with spigot(male)ends oriented downstream.
G. All force mains greater than twelve inches (12") shall be AWWA
specification C 905, Class 235, DR 18, color shall be green and shall
meet ASTM specifications D 3139 for pipe joined with rubber gaskets
conforming to ASTM F 477 or Ductile Iron Pipe shall conform to the
requirements of"Ductile-Iron Pipe, Centrifugally Cast in Metal Molds
for Sand-Lined Molds, for Water and Other Liquids", AWWA C151,
(ANSI A21.51), current revision. Pipe shall be lined with Protecto 401
ceramic epoxy lining or approved equal. Pipe thickness shall be the
minimum specified in C151.Bell(female)ends of pipe shall be installed
on upstream side with spigot (male) ends oriented downstream. All
ductile iron fittings shall be Ductile-Iron Compact Fittings AWWA
C153/A21.53.84 mechanical joint and restrained with Ebba "Meg-a-
lugs" or approved equal. The fittings shall be lined with Protecto 401
ceramic epoxy lining or approved equal. A two-inch (2") wide green
Page 11 of 31 Sanitary Sewer Design Criteria
marker tape with the words "Sanitary Sewer Forcemain" shall be
installed twelve inches(12")above the top of pipe during installation.
H. All constructed sanitary sewer lines shall be air tested for leaks and a
mandrel pulled for structural defects. All sanitary sewer testing shall
comply with or exceed the procedures and qualifications listed in Texas
Administrative Code, Chapter 217, Section 217.57. All sanitary
manholes shall pass a vacuum testing per Chapter 217, Section 217.58.
Upon successful completion of air testing and prior to placing the
sanitary sewer lines in operation, all constructed sanitary sewer lines
shall be flushed and cleaned prior to video. Every joint shall be videoed
360 degrees. A copy of video on DVD shall be submitted to the City
Engineer. Lines and joints shall be corrected if warranted from video
inspection. For procedures and requirements for the video inspection,
refer to City's Standard Specifications.
I. All public sanitary sewers and service leads shall have bedding and
backfill that shall comply with or exceed City of Pearland Standard
Details. Those sanitary sewers that are bore and jacked,microtunneled,
augured, or encased in a steel pipe may require special bedding and
backfill.
J. Backfill shall be in accordance with City of Pearland Standard Details.
All backfill within public right-of-ways and public easements shall be
compacted to a minimum of ninety-five percent (95%) of Standard
Proctor Density (ASTM D2922-78 and ASTM D3017-78), without
additional moisture control,cured and tested in accordance with ASTM
C31.
K. All sanitary sewer lines located underneath and within eighteen inches
(18") of any paving shall be bedded in cement stabilized sand in
accordance with the Standard Construction Details. The cement
stabilized sand shall be in accordance with the following requirements.
1. The cement shall be Portland Cement, Type I,ASTM C150.
2. The sand shall be clean, durable sand, with less than 0.5
percent clay lumps,ASTM C142: with less than 0.5 percent
lightweight pieces, ASTM C123; with organic impurities,
ASTM C40,not showing a color darker than standard color
and a plasticity index of less than six (6) when tested in
accordance with ASTM D423 and ASTM D424.
3. Compact to ninety-five percent (95%) Standard Proctor
Density (ASTM D2922-78 and ASTM D3017-78) in
maximum loose lifts of eight inches (8") thick. Actual
testing shall be required as deemed necessary by the City of
Pearland.
Page 12 of 31 Sanitary Sewer Design Criteria
4. The cement-sand mixture shall consist of at least 1.5 sacks
of cement per ton of sand. The cement-sand mixture shall
have a minimum unconfined compressive strength of one
hundred pounds per square inch(100 psi) in forty-eight(48)
hours,when compacted to a minimum of ninety-five percent
(95%) of Standard Proctor Density (ASTM D2922-78 and
ASTM D3017-78), without additional moisture control,
cured and tested in accordance with ASTM C31.
L. Sanitary sewers outside of paving shall be bedded in accordance with
the Standard Construction Details and the cement stabilized sand
utilized shall meet the same requirements.
M. Sanitary sewer bedding will be cement stabilized sand or approved
granular material. Bedding shall be compacted to ninety-five percent
(95%) Standard Proctor Density six-inches (6") over pipe prior to
backfilling the trench. In water bearing sand, washed shell or other
approved granular material will be required with geo-textile fabric wrap
as shown in the Standard Construction Details. When water bearing
sands are encountered, the City of Pearland shall be notified
immediately.
N. Public sanitary sewers and force mains shall be located in either the
public right-of-way or dedicated easements. Side lot and back lot
easements should be avoided. Side lot and back lot easements may be
granted special approval from the City Engineer only when a sanitary
sewer located in the street right-of-way is impossible from an economic
and engineering standpoint.
a. Lateral Location of Sewer in Right-of-Way/Easement
1) The location of the sanitary sewer within a dedicated
easement shall be along the centerline of the proposed
dedicated easement or as close to the centerline as can be
designed. In those instances where the dedicated easement
is adjacent to the public right-of-way, the lateral location of
the sanitary sewer shall be at the discretion of the Design
Engineer with approval from the City Engineer.
0. The final determination as to that portion of a street, alley, or dedicated
easement to be occupied by a proposed sanitary sewer rests with the
City Engineer. The City Engineer will take into consideration existing,
planned and proposed facilities such as manholes, pavement,
pipes/conduits, along with existing trees and shrubs,historical features,
wetlands or other unique surface conditions when arriving at a decision.
Page 13 of 31 Sanitary Sewer Design Criteria
P. The drawings of the sanitary sewer shall show the location of any
existing pipe or duct that might interfere with the construction of the
sanitary sewer and call to the attention of the City Engineer any known
obstacles that might be encountered in constructing the sanitary sewer
in any location under consideration. The Professional Engineer of
Record shall determine the existence of pipes,ducts,obstacles and other
utilities (i.e. gas, telephone, electric, fiber optic, cable, etc.) from a
visual survey on the ground plus research of the public records and
private records when available.
Q. Sanitary sewers within the City of Pearland's jurisdiction shall be
designed and installed at such a size and depth as to allow for orderly
expansion of the system, so as to avoid duplication in the future.
R. Sanitary sewers shall be designed and located to conform to regulations
of the Texas Commission on Environmental Quality. For water mains
crossing an existing or proposed sanitary sewer or force main, the
following clearances shall be provided for protection from
contamination. The minimum clearances will be approved only when
justified and field conditions so dictate. The latest edition of"Rules and
Regulations for Public Water Systems", of the Texas Commission on
Environmental Quality, shall be followed for minimum criteria and
instructions for water line crossings.
S. Sanitary sewers shall be separated from storm sewer lines by a minimum
of 4 feet of horizontal clearance and the storm sewer line shall be above
the sanitary line where possible, unless prior approval from the City
Engineer is granted.
T. For sanitary sewers crossing utilities other than water or storm sewer
(i.e. cable, gas, fiber optic, power, etc.), a minimum of 12 inches of
horizontal and vertical clearance shall be maintained as measured from
outside wall to outside wall, where possible.
4.3.7 Line Size
A. The minimum pipe diameter for a public sanitary sewer main shall be 8
inches.
B. Service leads 6 inches in diameter shall not serve more than the
equivalent of 2 single family lots or other equivalent types of small land
tracts.
C. Service leads for single family residential lots shall have a minimum
grade of 0.70% for a 6-inch line.
Page 14 of 31 Sanitary Sewer Design Criteria
D. The average daily flow for the design of sanitary sewers shall be based
on minimum 320 gallons per equivalent single-family connection and a
peaking factor of 4 (minimum). Designer to determine the total
equivalent connections based on the residential, commercial, or
industrial development being proposed. Submit documents on proposed
connections, flows and sizes to the office of City Engineer for review
and approval.
E. For commercial service leads, the required size of the line shall be
established from the plumbing drawings. Commercial, industrial, and
office areas shall be designed for an average daily flow that can be
anticipated from the contributing area.
F. Commercial sewer service leads shall be 6 inch pipe or larger. A single
6 inch commercial service connection shall not serve more than one
commercial lot or parcel. Four inch service leads for commercial
developments shall not be allowed.
G. Sewer mains hall end at a manhole.
H. The City Engineer shall have final review and approval authority as to
the size and depths required for sanitary sewer mains and lateral sewers.
4.3.8 Line Depth
A. The sanitary sewer should be laid with the top of the pipe a minimum
of 3 feet below the surface of the natural ground or finished grade.
B. Sanitary sewers laid in street rights-of-way with a curb and gutter
section shall have a minimum cover of 3 feet from the top of the pipe to
the flowline elevation of the gutter in the street at all locations. The
Professional Engineer of Record shall account for any anticipated future
sanitary sewer extension whereas the future sanitary sewer extension
shall have a minimum 3 feet of cover from the top of the pipe to the
flowline of the gutter of the street. The Professional Engineer of Record
shall adjust the depth of the proposed pipe accordingly. The City
Engineer reserves the right to require greater depth where the need is
perceived.
C. Sanitary sewers laid in street rights-of-way with crowned roads and
roadside ditches shall have a minimum depth of 6 feet from the crown
of the road to the top of the pipe and an absolute minimum cover of 3
feet below the flowline of a roadside ditch. The City Engineer shall
have final determination on any deviation from these criteria.
4.3.9 Line Grades
Page 15 of 31 Sanitary Sewer Design Criteria
A. The following table lists the minimum grade for 6-inch to 36-inch
diameter public sanitary sewers. The minimum velocity for a sanitary
sewer flowing full shall be 2.3 feet per second (fps). The maximum
recommended grade shall be calculated by the Professional Engineer of
Record for a maximum velocity of 4.5 fps based on a Manning equation
for full flow with the Manning's"n"equal to 0.013.The use of different
pipe materials will not alter the use of n=0.013 for the purposes of
design.
Table 4.1
MINIMUM GRADES FOR SANITARY SEWERS(TCEQ Minimum)
PIPE SIZE MINIMUM GRADE(PERCENT)
6 0.65
8 0.44
10 0.233
12 0.26
15 0.119
18 0.115
21 0.13
24 0.11
30 0.074
36 0.059
B. For sanitary sewers larger than 36 inches (36") in diameter, the
Professional Engineer of Record shall determine the appropriate grade
utilizing the Manning Formula, n=0.013, and a full pipe maximum
velocity of 4.5 fps and minimum velocity of 3.0 fps.
4.3.10 Gravity sanitary sewer mains shall be laid in straight alignment with
uniform grade between manholes. Grade and alignment changes without
the use of manholes shall not be allowed.
4.3.11 Unequal size sewers shall be designed so that the inverts of the pipes are
matched at manholes. The upstream sewer may be designed so that the flow
line of the upstream is higher than the flow line of the downstream sewer.
When the flow line of the upstream sewer is raised more than twenty-four
inches (24") above the flow line of the downstream sewer, a drop manhole
connection is required, except as specifically approved by the City
Engineer.
4.3.12 Sanitary sewer service leads shall be laid at a minimum sixty-five
hundredths of a percent(0.65%) slope.
4.3.13 Manholes
A. Type: Manholes shall be precast concrete manholes in accordance with
Standard Details and Specifications. No brick manholes shall be
allowed.All manholes shall be coated. Refer to Standard Specifications
Page 16 of 31 Sanitary Sewer Design Criteria
for types of coatings. Standard manhole shall have 5'inside diameter.
Larger diameter manholes may be required due to sewer main size,
numbers, or configuration at the manhole. It shall be the responsibility
of the Professional Engineer of Record to ensure that proper diameter
manholes is specified. All precast manholes shall conform to the latest
ASTM requirements. Manhole covers shall be 32" diameter or larger
and have the words"Sanitary Sewer"and the City of Pearland logo cast
into the cover per Standard Detail. Hinged manholes shall be used in
ditch lines and floodplain areas. All manholes shall be installed with
stainless steel manhole inserts with 1/8 inch vents and strap handles.
B. Location: Manholes shall be placed at changes in alignment,changes in
grade, changes in size of sanitary sewers, at the intersection of sanitary
sewers, junction points, and either at street, alley, or easement
intersections. Clean-outs will not be permitted on public lines.
a. The maximum distance between manholes shall be determined
from Table 4.2 for 8 inch to 36 inch pipe diameters. Spacing for
manholes on sewer mains with diameters larger than 36 inches
shall be recommended on an individual basis by the Professional
Engineer of Record subject to City of Pearland approval.
Table 4.2
MAXIMUM DISTANCE BETWEEN
SANITARY SEWER MANHOLES
PIPE DIAMETER IN INCHES MANHOLE MAXIMUM SPACING IN FEET
8-15 400
18-36 400
>36 Per Designer of Record,subject to the City
Engineer Approval
b. Place manholes at the dead-end of sewer mains and lateral
sewers.
c. Manhole covers shall be cast iron, minimum 32" diameter and
traffic bearing type ring and cover.
d. Criteria for Manhole Junctures
(1) Connections between public sanitary sewers and the
manhole shall adhere to the following criteria.
(a) The elevation of the flowline of the
discharging sanitary sewer shall match the
elevation of the flowline of the receiving
sanitary sewer for both equal and unequal
pipe diameters.
(b) Drop manholes in accordance with Standard
Details are allowed. A drop connection or
Page 17 of 31 Sanitary Sewer Design Criteria
drop manhole is required when the difference
in elevation between the effluent flowline
and the influent flowline is greater than 36
inches; or where a service line is proposed to
tie onto a sanitary sewer trunk main of 18
inches in diameter or larger.
4.3.14 Manholes should be located as to minimize or eliminate the inflow of
stormwater into the sanitary sewer. The top of manhole rim shall be set a
minimum of 3 inches above the surrounding fmished grade when the
manhole is not in a paved roadway. Sealed manholes are required on all
newly constructed manholes within the 100-year flood plain. Vented
manholes are required a minimum of every 800 feet when not located in the
100-year floodplain. Unless approved by the City Engineer, the elevation
of the top of rim of a sanitary sewer manhole shall be at or above the be the
100-year base flood elevation for the area it is being built in. All manhole
rims that are 3 feet and greater above grade shall use Revolution Assembly
Rim and Cover. All manholes in ditches shall have water tight hinged ring
and cover.
4.3.15 No cast-in-place manhole is allowed,unless approved by the City Engineer.
4.3.16 Steps in manholes shall not be allowed.
4.3.17 All manhole adjustments shall be made with precast concrete rings when an
additional precast vertical section is too large. No brick shall be used for
manhole adjustments.
4.3.18 All manholes shall be tested and witnessed by the City inspector by the
construction contractor and results provided to the City Engineer before
being accepted by the City for maintenance. The City reserves the right to
require retesting of manholes if there is reason to question the results. All
manhole testing shall comply with or exceed the procedures and
qualifications listed in Texas Administrative Code, Chapter 217, Section
217.58.
4.3.19 Manholes shall have a traffic bearing frame and cover Manholes shall have
a design strength of 4500 psi and in compliance with ASTM C478
reinforcement.
4.3.20 Sewers laid in easements shall have a manhole at each side of a street
crossing.
4.3.21 Manholes should be located to eliminate the inflow of storm water into the
sanitary sewer. The top of manhole rim elevation shall be shown on the
plans for all sanitary manholes. Manholes shall not be located within street
Page 18 of 31 Sanitary Sewer Design Criteria
pavement. Manholes shall have inflow protection inserts, minimum
thickness of one-eight inch(1/8"),made of stainless steel as approved in the
standard details and approved product list. Insert shall include a lift strap
and vent hole with vent disk. Where gasketed manhole covers are required
for more than three(3)manholes in sequence,an alternate means of venting
shall be provided at less than one thousand five hundred feet (1500')
intervals.
4.3.22 Manholes shall be constructed in accordance with the City of Pearland
Construction Details. The diameter of a manhole constructed over the
center of a sewer shall vary with the size of the sewer. For eight-inch (8")
through twelve-inch (12"), the manhole shall be five-foot (5') minimum
diameter, for fifteen-inch (15"), -through twenty-seven-inch (27") shall be
five-foot(5')minimum diameter;thirty-inch(30")and thirty-six-inch(36")
shall be six-foot(6')minimum diameter. Manholes deeper than twelve feet
(12')shall be a minimum of five-foot(5')diameter or six-foot(6')diameter
pending on pipe size. If a drop structure is required the manhole shall be a
minimum of five-foot(5') in diameter.
4.3.23 A drop manhole is required for pipes that have a change in elevation greater
than twenty-four inches (24"). The manhole will be a minimum five foot
(5') diameter. The use of an interior drop is required. Drop structure will
be provided by Reliner"inside drop bowl" or approved equal and attached
with stainless steel hardware.
4.3.24 All manhole adjustments shall be made with three inch(3")precast concrete
rings. A maximum of five (5) adjustment rings are permitted.
4.3.25 All new manholes shall have an interior surface coated with an approved
epoxy coating a minimum of 100 mils thick. If the project requires a
rehabilitation of an existing manhole the use of approved calcium aluminate
coatings will be required. Bituminous coatings are not allowed. Approved
coatings are listed in the Approved Products List. Coatings shall be tested
with a Holiday tester. Testing shall be in accordance with latest edition of
NACE "Standard Recommended Practice Discontinuity Testing of
Protective Coatings". All holidays shall be marked and repaired and
retested. All joints shall be grouted smooth prior to installation of the
interior coating. Should the manhole be pre-coated at the place of
manufacturing the joint shall be grouted smooth and the grouted area shall
be coated in accordance with this section.
4.3.26 Fiberglass manholes are not allowed as part of public sanitary sewer
systems. All manholes within public right-of-ways and public easements
shall be pre-cast manholes.
Page 19 of 31 Sanitary Sewer Design Criteria
4.3.27 Where unequal size pipes enter a manhole, inverts of pipes are required to
be at the same elevation,unless due to an elevation drop connection.
4.3.28 Service connections entering a manhole twenty-four inches (24") or more
above the flow line of the manhole shall include an internal drop pipe with
fittings. The drop shall consist of a"Reliner"internal drop bowl system,or
approved equal,installed adjoining and anchored to the wall of the manhole,
with all stainless steel hardware and fasteners. The cored opening for the
pipe shall be secured with "Linkseal", grouted and the manhole coating
shall be repaired per the coating manufacturer's recommendations
4.3.29 Provide adequate markings on site and accurate as-built locations, so that
the service connections stub-out can be recovered at the time that the
connection to the service is made.
4.3.30 Lift Stations
A. Lift station design and construction drawings as well as design
requirements and pertinent data shall be designed in accordance with
TCEQ Design Criteria Chapter 217, Sections 217.59 thru 217.63 and
sealed by a Professional Engineer registered in the State of Texas and
submitted with the construction drawings for review by the City
Engineer.Lift Stations should be considered only when a gravity system
cannot be achieved from both an engineering and an economic
standpoint. Lift stations should only be considered with prior approval
from the City Engineer or where the lift station is designed to be
temporary in nature. A preliminary design meeting with the City
Engineer is required. Designer to provide a master development plan
for the service area of the proposed lift station.
a. The lift station site shall be conveyed in fee to a utility district,
the City of Pearland, or other acceptable public entity. The site
may be part of a larger site that includes a public wastewater
treatment facility or other facility. The site shall have a
minimum size of 50 feet by 50 feet. Site access shall be
provided by a 15-foot (15') wide public right-of-way with an
approved,all-weather access road a minimum of 12 feet(12')in
width. Wet well structures shall be a minimum of 12 feet from
outside walls of structure to the site boundary fencing. Fencing
shall be in conformance with the City of Pearland Zoning
Ordinance.
b. Use drainage swales, sidewalls and driveways, culverts, storm
sewers, or a combination thereof for internal site drainage. Site
drainage may sheet flow to a public right-of-way. Storm sewer
systems,if provided shall be sized in accordance with applicable
Page 20 of 31 Sanitary Sewer Design Criteria
design guidelines.
c. The top of the wet well and all electrical controls shall be located
12-inches above the 500-year floodplain or 3 feet above the top
slab of the lift station wet well, whichever is greater, and the
design engineer shall take into consideration wave action,which
may exceed this elevation. Entry to the site must be accessible
during a 25-year flood.
d. All gravity sanitary sewers discharging to the wet well shall be
located where the invert elevation is at or above the liquid level
of the highest pump's "ON" setting to achieve the firm pumping
capacity. Gate valves and check valves shall not be located in
the wet well,but may be located in a valve vault or on a concrete
slab.Piping shall be spaced to maintain the pump manufacturer's
minimum clearances between pumps.
e. Size the diameter of the wet well, hatches, and hatch spacing to
accommodate the selected pumping equipment. Consideration
should be given to the dimensions of the ultimate pump in a
multi-phased lift station to ensure adequate clearances. Provide
a minimum of eighteen inches(18")of clearance from the inside
wet well wall to all flanges to enable removal of all bolts. Pre-
cast concrete wet wells may be used in any diameter provided
calculations demonstrate that wet well thickness and material
weight will resist imposed up-lift pressure. Provide hatch safety
nets with aluminum sliding rails or Flygt Safe-hatch access
cover.
f. The wet well volume shall be based on the minimum cycle time
of the largest pump planned for the lift station plus additional
depth to prevent motor overheating and vortexing. Wet well
working volume should be sized to allow for the recommended
pump cycle for each pump. The cycle time shall not be less than
those listed below:
CYCLE TIME
Motor Size Cycle Time
(Horsepower) (Minutes)
<50 6
50-100 10
>100 15
g. The "OFF" elevation of the submersible pumps shall be deep
enough to prevent vortexing and motor overheating. The
design engineer shall verify with all pump manufacturers on
Page 21 of 31 Sanitary Sewer Design Criteria
the List of Acceptable Manufacturers that each pump is
capable of operating continuously at the "OFF" elevation
shown on the plans.
h. The wet well floors shall have a minimum of 10 percent slope
to the pump intakes and have a smooth finish. There shall be
no wet well projections,which will allow deposition of solids
under normal operating conditions.The inlet structure shall be
designed to minimize turbulence.
The wet well shall have a vent sized such that the maximum
velocity of air through the vent is 600 feet per minute at the
firm pumping capacity. Vents shall have a stainless steel
insect screen that is easily replaceable and will prevent the
entrance of rainwater. Vent pipes shall be corrosion-resistant.
j. Access shall be provided to underground valve vaults.
Stairways shall have corrosion-resistant, non-slip steps and
conform to OSHA regulations with respect to rise and run.
Where ladders are utilized in lieu of stairways, ladders shall
conform to OSHA requirements.
k. Floor drains from valve vaults to wet wells shall be designed
to prevent gas and raw sewer water from entering the valve
vault. Such designs shall include "P" traps and floating ball
type backwater valves.
1. All walls shall be a minimum of 18 inches from the outermost
edge of all flanges to enable removal of all bolts. Pipes shall
have a minimum spacing greater than that required by the
pump manufacturer for minimum pump spacing. Swing
check valves shall be positioned such that the shafts may be
removed without removing the valve body.
m. Design shall follow the latest version of ACI 350 with the
exception that the minimum concrete cover over steel
reinforcing shall be at least four inches (4") where in contact
with raw sanitary sewer. Wet wells shall be designed to resist
the effects of buoyancy assuming full saturation of the
surrounding soils to the finished grade or the 100-year
floodplain, whichever is greater. Surface friction shall not be
included in the design unless a friction factor is provided in a
geotechnical report signed and sealed by a licensed
professional engineer. A safety factor of 1.1 shall be used for
buoyancy resistance. Wet well walls shall be designed to
withstand lateral earth pressures and static water levels at
Page 22 of 31 Sanitary Sewer Design Criteria
finished grade as outlined in ACI 350. At a minimum, 3,500
psi concrete shall be used. Class III or IV RCP may be used in
lieu of cast in place concrete if structural calculations are
provided showing that sufficient strength exists to resist
construction and final loadings. Top slabs shall be designed
for a uniform loading of 100 pounds per square foot and a
point load equal to the weight of the largest pump planned for
the lift station at any location.
n. Hatches shall be constructed entirely of aluminum or stainless
steel and designed for a minimum of 150-pound-per-square-
foot load. The underside of the hatch shall have the following
stenciled in red paint: "Warning! Confined Space Entry."
Where individual hatches are incorporated into the top slab,
the separation distance from inside face to inside face shall be
a minimum of 12 inches.
o. Where riser pipes pass through the top slab,offsets or two 45-
degree bends shall be used to provide clearance between the
outside diameter of the pipe and the inside face of the hatches.
The amount of clearance will be determined by the diameter
of the slab reinforcing and the maximum aggregate diameter.
p. Use of vault-type OR above-ground valves and piping is
permitted. Valves shall be mounted in a concrete vault, or on
an above-ground concrete foundation. Isolation and check
valves shall not be located in the wet well.
q. Pumps shall be of a non-clog design, capable of passing a 3-
inch diameter or greater incompressible sphere,and shall have
suction and discharge openings a minimum of 4 inches in
diameter. Pump seals shall be silicon carbide or tungsten
carbide.
r. Pumps shall be sized to operate at optimum efficiency.
Minimum acceptable efficiency at the operating point shall be
sixty percent(60%), unless specifically approved by the City
Engineer. Leak detection sensors shall be provided in the
motor housing of submersible pumps. Pumps shall be
securely supported,per manufacturer recommendations, so as
to prevent movement or vibration during operation. Rail-type
pump support systems shall be provided for submersible
pump installations.That allows pump removal and installation
without requiring dewatering of or entry into the wet well.
Rails, lifting chains, and hardware shall be constructed of
Series 300 stainless steel.
Page 23 of 31 Sanitary Sewer Design Criteria
s. Electric motors shall be sized so as to operate at maximum
design load without use of the service factor. Electric motors
shall be 120-volt single-phase, 240-volt or 480-volt 3-phase.
Motor service factor shall be a minimum of 1.15. Thermal
protection shall be provided in the motor housing. Electric
motors (excluding submersible units) shall be equipped with
space heaters.
t. The following electrical power sources shall be considered for
serving lift stations:
1. For stations where total pump motor sizes do not exceed
30 hp,and where any individual pump motor size does not
exceed 20 hp, 120/240-volt, three-phase service is
recommended.
2. For stations where individual pump motor sizes do not
exceed 5 hp and motor ratings are available as single-
phase, and where three-phase service is not available,
120/240 volt, single-phase service may be used.
3. For stations requiring pump motors that are available in
only three-phase ratings and where three phase electrical
service is not available (or not economically feasible),
120/240-volt, single-phase service with a three-phase
inverter unit is acceptable as a last resort but is not
recommended. Inverters are available for up to 100-hp
motor sizes.
4. For stations where total pump motor sizes exceed 30 hp
and where individual motor sizes exceed 20 hp, 480/277-
volt, three-phase service is recommended.
5. Where owner has an existing portable generator with only
480/277-volt, three-phase output, it may be more
advantageous to utilize 480-volt, three- phase power for
the smaller stations.
6. Emergency power connections shall require a manual
transfer switch and generator connector.
u. Controls and equipment shall be selected from the City of
Pearland Approved Products List. The pump controller shall
be a solid state, programmable pump controller with pump
alternator, submersible level transducer,back-up floats,alarm
Page 24 of 31 Sanitary Sewer Design Criteria
contacts, and power supply. The use of a Variable Frequency
Drive is acceptable. Lightning and surge protection shall be
installed on the Main Power Bus, single- or three-phase, as
applicable.
v. The following controls and indicators shall be provided.
1. Pump HOA Selector Switch(for each pump)
2. Alarm Reset Switch
3. Seal-Fail and Over-Temp Reset Switch (for each pump
protection module supplied by pump manufacturer)
4. Phase-Fail Light
5. Pump Run Light(for each pump)
6. Control Power Light On
7. Pump Seal-Fail Light(for each pump protection module -
supplied by pump manufacturer)
8. Pump Over-Temp Light (for each pump protection
module - supplied by pump-manufacturer)
9. High Level Alarm Indicator
10. Alarm Rotating Beacon Light
11. Pump Run Elapse Time Meter(for each pump)
w. The following motor protection devices shall be provided.
1. Motor Circuit Protectors (MCP's) or circuit breakers
2. Motor Overload Current Trip Devices or C.T.'s with
Relays (for each motor)
3. Motor Over-Temp and Seal Fail Relays (for each motor-
furnished by pump motor manufacturers)
4. Phase Fail Relay
x. Level Controls
1. Primary: Solid state submersible pressure transducer, rated
for wastewater application
2. Back-up: PVC ball type float with mercury switch-high and
low level
y. Operation: As level rises, the submersible level transducer
detects the pressure change and sends a 4-20 MA signal that
is proportional to wet well level to the pump controller.
1. Each pump is brought on as level rises,and when wet well
level falls back to a preset level, all pumps stop.
2. Pump alternator in the controller alternates lead/lag pump
selection at end of each pumping cycle.
3. If pumps fail to draw down wet well, high-level alarm
Page 25 of 31 Sanitary Sewer Design Criteria
signal is initiated at the pump controller and controller
automatically switches to standby floats for activation of
pump controls.
4. In the event of fail signal from transducer, controller
automatically switches to floats.
z. Alarm Signals
1. Alarms activate local indicator lights and send signals to
an approved autodialer.
aa. Pump Cable Terminal Boxes
1. NEMA 4X stainless steel boxes mounted near pump
access hatch for termination of pump power and control
cables and for termination of transducer and float cables.
2. All hub-type conduit entries.
bb. Control Panel Enclosure
1. NEMA 4X stainless steel enclosure on factory stainless
steel stands with inside swing door, back plate, quick
release latches, and hooking clasp.
2. All hub-type conduit entries.
cc. Emergency operations shall be considered. Provide fittings
and a blind flange that will be readily accessible for
emergency bypass pumping. Provide external hook up for an
emergency generator
dd. Force mains shall be a minimum of 4 inches in diameter,
unless used in conjunction with grinder pumps.Pump stations
with two pumps shall have force main velocities of a
minimum of 3 fps with one pump in operation. For pump
stations with three or more pumps, the force main velocity
shall not be less than 2 fps with the smallest pump only in
operation.Force main velocities shall not exceed 6 fps without
the engineer performing an analysis for possible high and low
negative surge pressures in the event of sudden pump failure.
ee. Isolation valves shall be provided on the discharge side of
pumps for submersible pumps and suction and discharge side
of pumps for dry pit lift stations,positioned such that the pump
and/or check valve can be isolated for removal. Plug valves
shall be used. Check valves shall be swing type with an
external lever and shall be installed in a horizontal position.
Page 26 of 31 Sanitary Sewer Design Criteria
Use of butterfly valves, tilting disc check valves, or other
valves utilizing a tilting disc in the pipe flow is not permitted.
ff. Surge relief valves, air release, and/or combination air and
vacuum valves shall be provided, as required.
gg. Lift station piping shall have flanged, grooved (Victaulic) or
flexible connections to allow for removal of pipe and check
valves without interruption of the lift station operation.
hh. Lift stations shall be designed to discharge the peak design
flow at the system head required and to operate efficiently
during any initial, interim, or ultimate design phase.
ii. Firm pumping capacity shall be provided, and is defined as
total station, maximum pumping capacity, with the largest
pumping unit out of service.
jj. Pump selection shall be based on the analysis of the system
head and pump capacity curves for the determination of
pumping capacities. System losses shall be calculated in
accordance with the Hydraulic Institute standards. The
selected C coefficient value for use in the calculation of
friction head losses per the Hazen-Williams Formula shall be
based on the selected pipe material for new and aged(20-year)
conditions.
kk. Force main velocities shall be included on the system curve.
11. Chemical feed odor control for force mains shall be provided
at the lift station if travel time, cycle time or other conditions
create the odor problems.
mm. Design considerations shall include corrosion control and
protection of concrete and metallic surfaces located within the
wet well/valve vault or within the immediate vicinity from the
effect of hydrogen sulfide (H2S) gas in the wastewater. The
effects of H2S gas should be minimized by reducing the
production or release of H2S gas from the wastewater
discharging to or being contained in the lift station. Design
and control methods shall include:
1. Protecting the exposed concrete and steel surfaces with an
epoxy lining. Refer to Approved Products List for list of
materials. Exposed piping shall be protected with a 100%
solids novolac epoxy or approved equal.
Page 27 of 31 Sanitary Sewer Design Criteria
2. The use of Series 300 stainless steel for equipment,piping,
devices, etc., exposed to corrosive gases.
3. Providing odor control equipment for wet well
atmospheric vents.
4. Design wet wells that lack interior corners,projections,or
areas that can result in the accumulation of solids. Design
interior surfaces with smooth finishes that facilitate
cleaning.
5. Provide wash-down water at site when possible.
nn. Corrosion protection shall be provided by coating interior
concrete surface of the wet well, structural steel, piping and
hangers, air systems, electrical, mechanical and other
components subject to a corrosive environment. All metal
components subject to a corrosive environment shall be
stainless steel or aluminum unless otherwise approved by the
City Engineer and Department of Public Works. Surfaces to
be protected include: •
1. Interior of wet well: The interior of the wet well shall be
coated with an approved epoxy coating. Refer to
Approved Products List for list of materials.
2. Piping located within wet well: Exposed piping shall be
protected with a 100% solids novolac epoxy or approved
equal.
3. Guide rails, lifting chains, hardware, and miscellaneous
metal shapes located within wet well shall be
constructed/manufactured of Series 300 stainless steel.
oo. Lift station construction plans shall include drawings that
provide the following information:
1. Site layout
2. Plan and profile of pump station and associated site piping
3. Profile view of pump operational and control levels and
settings
4. Hydraulic system curve
5. Electrical wiring and control system schematics
6. Structural details
4.3.31 Design Analysis
A. Calculations of design flows for the overall development project shall
be approved by the City Engineer. Peak flow calculations shall include
potential inflow infiltration.
Page 28 of 31 Sanitary Sewer Design Criteria
B. All collection system lift stations shall utilize submersible pumps. A
minimum two(2)pumps shall be required for all lift stations. Capacity
of the pumps shall be such that maximum wet weather flow can be
handled with largest pump out of service.
C. A minimum peaking factor of 4 is required for pump sizing.
D. Pumps shall be sized to operate at optimum efficiency. Minimum
acceptable efficiency at the operating point shall be 60%.
E. Electrical equipment and electrical connections in wet well must meet
National Fire Prevention Association 70 National Electric Code
explosion prevention requirements, unless continuous ventilation is
provided.
F. Emergency operations should be considered. Provide fittings and a
blind flange that will be readily accessible for emergency bypass pump.
G. A geotechnical boring to a minimum depth 15' below bottom of wet
well and a foundation design recommendation is required.
4.4 QUALITY ASSURANCE
4.4.1 Prepare calculations and construction drawings under the supervision of a
Professional Engineer trained and licensed under the disciplines required by
the drawing. The final construction drawings must be sealed, signed, and
dated by the Professional Engineer responsible for the development of the
drawings. If more than one Professional Engineer was responsible for the
development of the design/construction drawings, then the appropriate
Professional Engineer should seal the drawings he/she is responsible for.
4.5 ADDITIONAL STANDARDS
4.5.1 If a lot or parcel is within 200 feet of an existing sanitary sewer then the site
shall extend the sewer main through the property and tie-on. Such building
shall comply with Section 74 Article 3 of the City of Pearland Code of
Ordinances.
4.5.2 Construction Features - In conjunction with the design, the engineer shall
determine the extent of, and fully detailed on the plans, all special
construction features required to complete the project in a safe, convenient,
and economic manner.
4.5.3 Bore and Jack-Bore and jack sections shall be specifically approved by the
Department of Public Works and clearly shown on plans by location and
Page 29 of 31 Sanitary Sewer Design Criteria
footage. Refer to the City of Pearland Standard Details. The following
criteria are generally used as a basis for setting bore and jack sections.
A. Public Streets - All existing public streets are to be bored and jacked
regardless of surface. Bore and jack length shall be computed as
roadway width at proposed bore plus five feet(5')to either side.
B. Driveways - Whenever it is cost effective, concrete driveways in good
condition shall be bored and jacked. Bore and jack length shall be
computed as driveway width at bore plus one foot (1') to either side.
Where driveways cross culvert pipe sections along open ditch streets
and the proposed wastewater main is in close proximity and parallel to
the culvert pipe, the length of bore shall be the same as the length of
culvert pipe.
C. Sidewalks - When the wastewater line crosses under a sidewalk four
feet(4')or more in width and in good condition,the sidewalk shall either
be bored and jacked or the sidewalk shall be removed and replaced to
the City of Pearland criteria,whichever is cost effective. Bore and jack
length shall be at least the width of the sidewalk. The proposed type of
construction shall be noted on the plans.
D. Trees - When saving trees and shrubs in a previously developed area is
a consideration, all trees six inches (6") and larger in diameter within
ten feet (10') of the centerline of the water main must be noted on the
plans. The water main shall be bored and jacked within the drip line of
any tree larger than six inches(6") in diameter.
E. Bore Pits - Bore pits shall be at least three feet (3') from back of curb
and five feet(5') from back of curb on a major thoroughfare. Bore pits
in highway,county road, or railroad right-of-way shall conform to these
requirements and to the requirements of the crossing permit and/or use
agreement. All bore pits shall be shored in accordance with OSHA
requirements. Bore pits and/or receiving pits to be located in street or
driveway paving, shall be shown on plans.
a. Open Cuts — Open cuts require specific approval of the City
Engineer. Where open cuts are allowed in street paving, plans
shall call for steel plate covers to be installed and maintained
over the cut during periods when contractor is not actively
engaged in work at the site. Streets that are open cut shall be
"saw cut" prior to pavement removal. Saw cut shall be full
depth.
4.5.4 All existing developed areas shall be restored to original condition after
construction
Page 30 of 31 Sanitary Sewer Design Criteria
4.5.5 Proper barricading and signage, conforming to the Texas Manual of
Uniform Traffic Control Devices' latest edition, shall be required on all
projects. Adequate signage for vehicular and pedestrian traffic shall be
installed. A traffic control plan shall be submitted to the City Pearland and
approved by the City Engineer for all streets open to travel by the public.
Page 31 of 31 Sanitary Sewer Design Criteria
CITY OF PEARLAND
CHAPTER 5
STORM SEWER DESIGN CRITERIA
ENGINEERING DESIGN CRITERIA MANUAL
December 2018
Page 1 of 65 Storm Sewer Design Criteria
CHAPTER 5
DRAINAGE SYSTEM DESIGN REQUIREMENTS
5.1 GENERAL
This chapter includes criteria for the design of storm drainage improvements for the City
of Pearland, Texas. These Storm Drainage Design Requirements shall be effective within
the City of Pearland and in the subdivisions located within its extraterritorial jurisdiction.
All drainage work proposed for design within these limits are to adhere to these criteria
explicitly. Any questions regarding their use or function should be addressed to the City
Engineer.
5.1.1 Background
Over the years, a number of methods have been used in Brazoria County and
adjacent counties for discharge determination in the design and analysis of flood
control facilities. The methods included various forms of the Rational Method,
U.S. Soils and Conservation Society synthetic unit hydrograph analysis using
existing stream gaging records and computer programs developed by the Corps of
Engineers,and U.S.Geological Survey generalized regression equations developed
for the area.
In the mid-1960's,the Harris County Flood Control District(HCFCD)and the City
of Houston commissioned a detailed hydrologic study of Harris County which
resulted in the development of the Site Runoff Curve (discharge versus drainage
area relationships)and unit hydrograph methodologies used for the design of flood
control and drainage facilities.
In June of 2001,Tropical Storm Allison came ashore on the Upper Texas Coast and
produced record rainfall amounts and pervasive flooding in Harris and surrounding
counties,including the Clear Creek Watershed. In October of 2001,through a joint
effort between FEMA and HCFCD, Harris County began the Tropical Storm
Allison Recovery Project (TSARP). Flood Insurance Studies including for Clear
Creek Watershed were finalized in June 2007.
Special care must be taken to make sure that the correct models and methodologies
are used for projects that require FEMA approval. In any case, for projects
requiring FEMA approval,design engineers should use the current effective model
Page 2 of 65 Storm Sewer Design Criteria
of the study stream. For modification requirements to FEMA floodplain and/or
floodway,refer to Chapter 2.
In the case that FEMA approval is not required for the project, design engineers
should use the methodology presented in this manual to design drainage facilities
in the City of Pearland.
5.1.2 Previous Design Requirements
The criteria of this Manual supersedes the previous document of the same name
dated October 2016. All items listed herein are intended to supersede those
documents, so all designs of drainage facilities within the City of Pearland,
including all subdivisions within its extraterritorial jurisdiction, shall be based on
the criteria of this Manual from this time forward, until such time as it may be
revised or replaced.
5.2 DRAINAGE POLICY
5.2.1 Design Requirements
The drainage criteria administered by the City of Pearland for newly designed areas
provides protection of habitable areas from flooding by large storm events. This is
accomplished with the application of various drainage enhancements such as storm
sewers,roadside ditches,open channels,detention and overland(sheet)runoff. The
combined system is intended to prevent flooding of houses by extreme events up to
the level of a 100-year storm.
Recognizing that each site has unique differences that can enhance proper drainage,
the intent of these criteria is to specify minimum requirements that can be modified,
provided the objective for drainage standards is maintained and such modifications
are made with the approval from the office of the City Engineer.
5.2.2 Street Drainage
Street ponding of short duration is anticipated and designed to contribute to the
overall drainage capability of the system. Storm sewers and roadside ditch conduits
are designed as a balance of convenience and economics. These conduits are
designed to convey less intense,more frequent rainfalls with the intent of allowing
for traffic movement during these events. When rainfall events exceed the capacity
Page 3 of 65 Storm Sewer Design Criteria
of the storm sewer system,the additional runoff is intended to be stored or conveyed
overland in a manner that reduces the threat of flooding to habitable structures.
5.2.3 Floodplain Management
A. The City of Pearland is a participant in the National Flood Insurance
Program's (NFIP's) Community Rating System (CRS). As a CRS
community, the City is required to develop and implement various
programs intended to reduce flood risk such as identifying drainage problem
area, maintenance of existing drainage system, construction of drainage
project, outreach to the community etc. As a result of the community's
commitment to reduce the flood risk, the residents of the City are entitled
to receive discounted flood insurance premium based on the City's CRS
ranking as evaluated by CRS
B. All runoff impacts created by development shall be mitigated, so post-
project runoff rates and flooding levels are equal to or less than equivalent
pre-project conditions. Stormwater detention requirements are presented in
Section 5.8.
C. Fill placed in the 100-year flood plain,as designated on the Flood Insurance
Rate Map, and below the 100-year base flood elevation shall be mitigated
by the removal of a like amount (ie. 1 cubic yard fill to 1 cubic yard
removal) of compensating cut in the vicinity of the fill, while maintaining
hydraulic connectivity to the existing floodplain.
D. See Section 2.12 Floodplain Management for additional details and
requirements.
5.2.4 Relationship to the Permitting and Platting Process
Approval of storm drainage is part of the review process for planning and platting
of a new development. The review of storm drainage is conducted by the
Engineering Department.
5.2.5 Final Drainage Plan and Plat
A detailed drainage plan for each proposed development shall be prepared by a
Registered Professional Engineer and shall be presented to the City Engineer for
review and approval. The plan shall consist of the detailed design drawings for all
drainage improvements and structures, rainfall runoff and impact data and notes to
be included as applicable on the Final Drainage Plan as specified in Sections 5.5
through 5.9.
Page 4 of 65 Storm Sewer Design Criteria
The following items, at a minimum, shall be shown on a plan for a development:
1. Name,address,phone number,and contact person of engineer that prepared
the plans.
2. Scale of drawing with a minimum scale of 1"= 100'.
3. Benchmark and reference benchmark with year of adjustment.
4. Location or vicinity map drawn to a scale.
5. Date on all submittals with date of all revisions, including month, day, and
year.
6. Contour lines at 0.5-foot intervals or greater with a minimum of 2 contours
covering the entire development and extending beyond the development
boundaries at least 100 feet on all sides for developments over 5 acres and
50 feet for developments under 5 acres.
7. Lot grading plan, which provides for the passage of sheet flow from
adjacent property. The lot grading plan shall include the proposed elevation
of each corner of the lot.
8. A 100-year sheet flow analysis that provides direct access to the detention
facility or main outfall.
9. Drainage area divides for project area,with peak runoff rates for each inlet,
structure, or drainage area.
10. Locations of pipelines, drainage structures, buildings, or other physical
features on the property and adjacent rights-of-way.
11. True locations of existing creeks, bayous, streams, gullies, and ditches, as
determined by actual ground survey current within one year of approval of
the Preliminary Plan. Show stream alignment 200 feet upstream and 200
feet downstream of development.
12. Cross sections of detention facility, ditches and earthworks.
13. Details of all ditches,which are to convey rainfall runoff from a subdivision
and/or through a subdivision to the appropriate drainage artery and location
of that drainage artery.
Page 5 of 65 Storm Sewer Design Criteria
14. Drainage easements and dedicated right-of-way along all creeks, bayous,
streams, gullies, and ditches.
15. Bridges which span any creek, bayou, stream, gully, or ditch and
maintenance responsibility and/or ownership of such structures.
16. Culvert type and size shall be shown. No culvert shall be less than 18" in
diameter, without special permission by the City Engineer.
17. Copy of TxDOT permit application, if applicable.
18. Copies of letters of approval from entities holding easements or rights-of-
way to be crossed.
19. An erosion control plan acceptable to both the City and the T.C.E.Q. must
be presented with all plans. Copies of all submittals to the T.C.E.Q. shall
be delivered to the City.
20. Seal of a Registered Professional Engineer on all plans and Registered
Public Surveyor or State Licensed Land Surveyor on the plat. The Grading
and Drainage Plan must be sealed by a Civil/Environmental or Structural
Engineer.
21. The lowest chord of all bridges shall be a minimum 12"above the 100-year
water surface elevation, at or above the level of natural ground, or in
accordance with the FEMA latest regulations, whichever is greater.
5.3 REFERENCES
1. Brazoria Drainage District No. 4, "Rules, Regulations, & Guidelines", November
5, 1997 (BDD4 Regulations), amended April 2013.
2. Harris County Flood Control District, "Hydrology & Hydraulics Guidance
Manual", December 2009 (HCFCD Criteria).
3. Applicable Portions of the City of Houston Design Manual, Chapter 9, "Storm
Sewer Design Requirements",July 2015.
4. Ordinances of the City of Pearland(as currently amended).
Page 6 of 65 Storm Sewer Design Criteria
5. U.S. Army Corps of Engineers. HEC-RAS River Analysis System User's Manual
Version 4.1,The Hydrologic Engineering Center, Davis, California,January 2010.
6. U.S. Weather Bureau. "Rainfall Frequency Atlas for the United Stated for
Durations from 30 Minutes to 24 Hours and Return Periods from 1 to 100 Years,"
Technical Paper No. 40, January 1963.
7. U.S. Army Corps of Engineers. Civil Works Bulletin 52-8.
8. U.S. Army Corps of Engineers. HEC-HMS Hydrologic Modeling System User's
Manual Version 4.0, The Hydrologic Engineering Center, Davis, California,
December 2013.
9. Chow,V. T., Open-Channel Hydraulics, McGraw-Hill, 1959.
10. Ramser, C. E., Flow of Water in Drainage Channels, U.S. Department of
Agriculture, Technical Bulletin No. 129,November 1929.
11. Engineer Handbook, Hydraulics, Section 5, U. S. Department of Agriculture, Soil
Conservation Service, 1955.
12. Barnes, Harry H., 1967, Roughness Characteristics of Natural Channels, U. S.
Geological Survey Water Supply Paper, 1849.
13. King,H. W. and E. F. Brater,Handbook of Hydraulics, 6th Edition, McGraw-Hill,
1976.
14. Research Studies on Stilling Basins, Energy Dissipators, and Associated
Appurtenances, Bureau of Reclamation, Hydraulic Laboratory Report No. Hyd-
399, June 1, 1955.
15. Texas State Department of Highways and Public Transportation standard
specifications for Construction of Highways, Streets, and Bridges latest edition.
16. ASTM A796 Structural Design of Corrugated Steel Pipe, Pipe Arches, and Arches
for Storm and Sanitary Sewers.
17. Liscum, F., and B. C. Massey. "Technique for Estimating the Magnitude and
Frequency of Floods in the Houston, Texas,Metropolitan Area,"Water Resources
Investigations 80-17, U. S. Geological Survey, April 1980.
18. Federal Emergency Management Agency. Flood Insurance Study - Brazoria
County, Texas and Incorporated Areas,June 5, 1989.
Page 7 of 65 Storm Sewer Design Criteria
19. Federal Emergency Management Agency. National Flood Insurance Program and
Related Regulations, Index 44 CFR, October 1, 2002.
20. Hare, G. "Effects of Urban Development on Storm Runoff Rates," U. S. Army
Corps of Engineers, Galveston District, September 1970.
21. Malcolm, H. R. A Study of Detention in Urban Stormwater Management, Report
No. 156,Water Resource Research Institute,University of North Carolina,Raleigh,
North Carolina, July 1980.
22. Texas Water Development Board. "Study of Some Effects of Urbanization on
Storm Runoff from a Small Watershed," Report 23, August 1966.
23. Hydraulic Design of Stilling Basins and Energy Dissipators, Engineering
Monograph No.25,U. S.Department of the Interior,Bureau of Reclamation, 1964.
24. Viessman, Jr., Warren; John W. Knapp; Gary L. Lewis and Terence Harbaugh,
Introduction to Hydrology, Harper& Row, 1977.
25. Coenco, Inc. Master Drainage Plan, April 11, 1980, Revised 1988.
26. Rust Lichliter/Jameson. Flood Protection Plan for Brazoria Drainage District No.
4,Brazoria County, Texas,November 5, 1997.
27. U.S. Geological Survey, Water Resources Investigations Report 98-4044, Depth-
Duration Frequency of Precipitation for Texas,Austin, Texas 1998.
28. U.S. Geological Survey & Texas Department of Transportation, Atlas of Depth-
Duration Frequency of Precipitation Annual Maxima for Texas,June 2004.
29. USACE EM 1110-2-1417.
30. McCuen, Richard H., Prentice Hall,Hydrologic Analysis and Design, 1989.
31. City of Pearland Plat Amendment Ordinance No. 421.
32. City of Pearland Flood Damage Prevention Ordinance No. 532-6.
33. City of Pearland Flood Mitigation Exempt Ordinance No. 817-1.
34. City of Pearland City Right-of-Way Management Ordinance No. 669-3.
Page 8 of 65 Storm Sewer Design Criteria
35. City of Pearland Amending Chapter 27 for Sidewalk City Ordinance No. 741-5.
36. City of Pearland Maintenance of Stormwater Storage Facilities Ordinance No 1059.
5.4 DEFINITIONS
Backslope Drain: A drain or swale that collects overland peak discharge from
channel overbanks and other areas not draining into the
storm sewer collection system. These may be to prevent
unplanned runoff from entering a detention system, or from
entering a drainage ditch. They are also used to prevent
overland discharge from eroding the sides of a ditch or pond.
Benchmark: A point of known exact elevation,set and used by Surveyors
to start from to obtain elevations on other points of unknown
elevation. The known elevation is usually based on "mean
sea level" and is referenced to a"Year of Adjustment".
BDD4: Brazoria Drainage District No. 4.
cfs: Cubic Feet Per Second
City Engineer: An Engineer licensed in the State of Texas who is
responsible for reviewing drainage plans or plats under the
authority of and in the employment of the City of Pearland.
CMP: Corrugated Metal Pipe
Coefficient of Roughness: A number used to measure and compare the roughness of
pipe interior or open channel sides and bottom.
Commercial: Development of real estate for any purpose other than
"residential" as defined herein.
Conduit: Any open or closed device for conveying flowing water.
Construction: The building of a planned or designed project.
Continuity Equation: Q=VA
Where Q = discharge(cfs or cms)
V = velocity(ft/sec or msec)
Page 9 of 65 Storm Sewer Design Criteria
A = cross sectional area of conduit in
square feet or square meters.
Contour Line: A line on a map, chart or plan that follows a continuous line
of a certain known elevation.
Culvert: One or more pipes that carry the flow of water from one
point in a ditch or channel to another point in a ditch or
channel.
Design Storm Event: The rainfall intensity and/or depth upon which the drainage
facility will be sized.
Detention Control Structure:The outlet pipe or weir, and high-level spillway that limits
the discharge from a detention facility.
Detention Facility: A reservoir, dam, pond or other area where stormwater
collects and is held temporarily. The collected stormwater
is released at a calculated rate through a control structure.
Developer: A person or entity that develops land.
Development: A tract of land that has been improved or subdivided,
exclusive of land being used and continuing to be used for
agricultural purposes. Improvement of land includes
grading, paving, building structures, or otherwise changing
the runoff characteristics of the land.
Development Engineer: An Engineer licensed in the State of Texas who is
performing work for a Developer.
Drainage Area Map: Area map of watershed which is subdivided to show each
area served by each storm drainage subsystem.
Drainage Arteries: Natural or man-made ditches or channels that intercept and
carry stormwater on to a larger major creek,bayou or stream.
Drainage Plan: An engineering representation of the peak discharge of
rainfall runoff on or onto a particular area, and off of that
same area. It may also include systems that will be used to
detain or control runoff and provide flood control for a
development, subdivision, or structure.
Page 10 of 65 Storm Sewer Design Criteria
Drainage System: A series of swales, storm sewers, ditches and creeks which
function to collect and convey stormwater runoff in a
watershed.
Easement: An area designed and dedicated for a specific use but
remains the property of the owner out of which it is a part.
The uses may be for drainage, maintenance, access, future
widening of channel or ditch, or other specific uses.
FEMA: The Federal Emergency Management Agency, which
administers the National Flood Insurance Program.
FIRM: Flood Insurance Rate Maps published by a Federal
Emergency Management Agency.
Flood Plain Administrator: Person identified by the governing municipality or County
as responsible for administering the National Flood
Insurance Program for the City or County in accordance with
guidelines established by FEMA.
HCFCD: Harris County Flood Control District.
HDPE: High Density Polyethylene
HEC-HMS: "Hydrologic Modeling System" computer program written
by the U.S. Army Corps of Engineers.
HEC-RAS: "River Analysis System"computer program written by U.S.
Army Corps of Engineers.
Hydraulic Analysis: The study and/or definition of the movement of stormwater
through a drainage system.
Hydraulic Grade Line: A line representing the pressure head available at any given
point within the drainage system.
Hydrologic Analysis: The study and/or definition of the properties, distribution
and circulation of stormwater runoff over land or in the soil.
Hydromulching: A process that prevents or helps to prevent erosion of the
soil. When sprayed on an exposed slope, it seals the surface
and seeds it with vegetation.
Page 11 of 65 Storm Sewer Design Criteria
ICPR: Interconnected Channel and Pond Routing computer
program by Streamline Technologies, Inc. Computes
unsteady gradually varied flow.
Impact: The effect of a proposed development on the hydrology or
hydraulics of a subarea or watershed as defined by an
increase or decrease in peak discharges or water surface
elevations.
Impact Data: Data required to support the Developer's Engineer to show
the effect the proposed development will have on the rainfall
runoff rates, rainfall concentration times and the surface
level of the affected creek, stream,gully, or ditch into which
proposed development runoff drains.
Impervious Cover: A land surface cover which does not allow the passage of
stormwater into the underlying soil. Used in hydrologic
analysis to calculate the amount of stormwater runoff from
an area.
In-Fill Development: Development of open tracts of land in areas where the storm
drainage infrastructure is already in place and takes
advantage of the existing infrastructure as a drainage outlet.
Manning's Equation: V=(K/n)R 2/3 S 1/2
Where K = 1.49 for English units,
1.00 for metric units
V = velocity(ft/sec or msec)
R = hydraulic radius(ft or m)
(area/wetted perimeter)
Sf = friction slope (headloss/length)
n = 0.013 for concrete pipes,
.011 for HDPE pipes,
0.028 for CMP
varies for earthen channels
Metering Device: A device or structure containing pipe, V-notch weir, slots
and other configurations designed to measure or regulate the
outflow.
Mitigate: To lessen or eliminate the impact of a proposed development
on the hydrology or hydraulics of a subarea or watershed.
Page 12 of 65 Storm Sewer Design Criteria
NAVD: North American Vertical Datum or Mean Sea Level,
pertaining to base elevations.
Outfall Structures: A structure made to contain the outfall pipe or peak
discharge,with necessary weir,slope paving,riprap,or other
methods to control velocity and prevent erosion, and may
contain the metering device.
Outflow: The final peak discharge from the development system into
another or existing drainage system.
Overflow: The peak discharge that will not pass through the design pipe
or structure and must go over a weir or some other relief
structure.
Peak Discharge: The maximum rate of stormwater runoff from a tract of land
or in a ditch or channel, as determined from the maximum
point in cubic feet per second of the calculated hydrograph
for the study area.
Plat: A formal drawing of property"lines and spaces that may, or
may not, be recorded.
Rainfall Data: Data pertaining to the amount of rainfall in a certain area and
occurring over a certain specified period of time.
Rainfall Frequency: The probability of a rainfall event of defined characteristics
occurring in any given year. Information on rainfall
frequency is published by the National Weather Service.For
the purpose of storm drainage design, the following
frequencies are applicable:
3-year frequency - a rainfall intensity having a 33%
probability of being equaled or exceeded in any given year.
5-year frequency - a rainfall intensity having a 20%
probability of being equaled or exceeded in any given year.
10-year frequency - a rainfall intensity having a 10%
probability of being equaled or exceeded in any given year.
Page 13 of 65 Storm Sewer Design Criteria
25-year frequency - a rainfall intensity having a 4%
probability of being equaled or exceeded in any given.
100-year frequency - a rainfall intensity having a 1%
probability of being equaled or exceeded in any given year.
Rainfall Runoff: The portion of the precipitation on the land that ultimately
reaches the drainage system.
Rational Formula: A method for calculating the peak runoff for a storm
drainage system.
Redevelopment: A change in land use that alters the impervious cover from
one type of development to either the same type or another
type and takes advantage of the existing infrastructure in
place as a drainage outlet.
RCP: Reinforced Concrete Pipe.
Regional Detention Facility:A detention facility that collects and holds stormwater from
more than one development or from one of the major creeks
or tributaries in the City of Pearland.
Residential: Of or pertaining to single family detached dwelling(s) not
including multi-family townhomes, condominium,
duplexes, or apartments.
Right-of-Way: A strip of land that is set aside and reserved for certain
purposes including drainage and maintenance, and possibly
future widening of a drainage channel.
Runoff That part of rainfall on property that does not soak in or
evaporate, and ultimately reaches drainage arteries.
Runoff Coefficient: A comparative measure of different soils, slopes and
growths, and improvements, for their capability of allowing
the peak discharge of water to move along and over them.
Sheet Flow: Overland storm runoff that is not conveyed in a defined
conduit and is typically in excess of the capacity of the
conduit.
Page 14 of 65 Storm Sewer Design Criteria
Site: A space of ground occupied or to be occupied by a building
or development.
Spillway: The part of the outfall structure that allows and controls the
"overflow"that does not go through the structure.
Subdivide: To divide a tract of land into two or more smaller tracts or
building lots.
Subdivision: A tract of land which has been separated from surrounding
tracts and has been divided into two or more lots.
Swale: A very shallow ditch that usually has very long sloping sides,
in some cases not much more that a small depression that
allows water to peak discharge in a somewhat controlled
manner.
TSARP: Tropical Storm Allison Recovery Project. Federally funded
flood study managed by Harris County Flood Control
District begun in October of 2001.
U.S.G.S. SIR 2004-5041: 2004 U.S.G.S Publication regarding rainfall depth-duration
frequency relationships for Texas.
Variance: A onetime formal exception to a particular rule or rules
granted for extenuating circumstances, by a City Council
resolution.
Watershed: A region or area bounded peripherally by a ridge of higher
elevation and draining ultimately to a particular watercourse
or body of water.
5.5 STORM SEWER AND ROAD-SIDE DITCH DESIGN REQUIREMENTS
Storm sewer structures shall be per City of Pearland Standard Details. Additionally,unless
otherwise noted,the City of Pearland also adopts the hardware requirements of the TxDOT
Specifications and Standard Drawings as necessary. Manhole covers shall include the City
of Pearland designation as shown in Standard Details. Grates, etc. shall have generic
designation.
Furthermore,all outfall pipes,ditches,and structures that enter District Channels shall also
be designed in accordance with BDD4Regulations or HCFCD Criteria. In such instances
Page 15 of 65 Storm Sewer Design Criteria
wherein a conflict of these criteria arises,the most stringent requirements of these shall be
utilized for the design.
To distinguish the adequacy of road-side ditches to be designed by the following
requirements of this section, it is important to note that these ditches DO NOT include
channels which receive runoff flows from any other outfall drainage sources other than
direct overland runoff flows. Design of channels that do receive outfall system drainage
can be found in Section 5.7of this Manual.
5.5.1 Determination of Runoff
The stormwater runoff(peak discharge) shall be determined for each inlet, pipe,
roadside ditch,channel,bridge,culvert,outfall, or other designated design point by
using the following standards applicable to the above requirements.
A. Application of Runoff Calculation Models
a. Acceptable Methodology for Areas Less Than 200 Acres
For areas up to 200 acres served by storm sewer or roadside ditch,peak
discharges will be based on the Rational Method. If the modeling is
associated with establishing a flood-prone area for purposes of a FEMA
submittal, the models to be used must be acceptable to that agency.
b. Acceptable Methodology for Areas Greater Than 200 Acres
Rainfall runoff modeling will be applied to areas greater than 200 acres
in size. Again, if the modeling is associated with establishing a flood-
prone area for purposes of a FEMA submittal, the models to be used
must be acceptable to that agency.
B. Rainfall Durations for Hydrologic Modeling
For design using the HEC-HMS model, the 24-hour design storm
isohyetograph will be used for rainfall data for drainage areas larger than
200 acres.
C. Application of the Rational Method
Use of the Rational Method for calculating the peak runoff for a storm
drainage system involves applying the following formula to runoff:
Q=CIA
Page 16 of 65 Storm Sewer Design Criteria
where: Q=peak discharge(cfs)
C=watershed coefficient
A=area in acres
I=rainfall intensity(inches per hour)
a. Calculation of Runoff Coefficient
The runoff coefficient "C" values in the Rational Method formula will
vary based on the land use. Land use types and "C" values which can
be used are as follows:
Land Use Type Runoff Coefficient*
Paved Areas/Roofs** 1.00
Compacted gravel, limestone 0.80
Residential Districts
Lots more than 1/2 acre 0.40
Lots 1/4 - 1/2 acre 0.50
Lots 8,000 sf.— 1/4 acre 0.55
Lots 5,000 sf.—8,000 sf. 0.60
Lots less than 5,000 sf. 0.70
Multi-Family areas
Less than 20 DU/AC 0.75
20 DU/AC or Greater 0.85
Business Districts 0.95
Industrial Districts 0.95
Railroad Yard Areas 0.30
Parks/Open Areas 0.30
Rice Fields/Pastures 0.20
Lakes/Detention Ponds*** 1.00
Dry Detention Ponds 0.85
*When calculating "C" values for proposed developed areas, multiply
listed values by 1.05 to reflect saturated conditions.
**Includes concrete and asphalt
***Includes wet detention facilities. Area will be computed from top
of slope.
Composite"C"values for mixed-use drainage areas are allowed for use
in the Rational Formula. These values are to be obtained by calculating
a weighted average of all the different "C" values of the sub-areas
contributing to each mixed-use drainage area. Any calculations of these
Page 17 of 65 Storm Sewer Design Criteria
Composite "C" values are to be provided as part of the drainage
calculations.
C=(CIA' +C,A,+C3A ...CnAn)
(Ai+A2+A3 ...An)
The calculations and an exhibit of surface types for use of composite
"C"values shall be included with the drainage calculations and provided
in plans.
b. Determination of Time of Concentration
The following method shall be used for determining the time of
concentration:
Tc=D/(60*v)+Ti
where: Tc=Time of concentration(minutes)
Ti=Initial time (minutes)
Use 10 minutes for developed flows
Use 15 minutes for undeveloped flows
D=Travel distance on flow path(feet)
V=Velocity(ft/sec)
The time of concentration shall be calculated for all inlets and pipe
junctions in a proposed storm drainage system or other points of runoff
entry to the system. Time of concentration shall be based upon the
actual travel time from most remote point in the drainage area to the
point of runoff. The design engineer shall provide a sketch of the travel
path with the computations.
The following minimum and maximum velocities shall be used when
calculating the time of concentration:
SURFACE UNDEVELOPED DEVELOPED
TYPE FLOWS MIN V(fps) FLOWS MIN V(fps)
storm sewer 3.00 3.00
ditch/channel 2.00 2.50
paved area 1.50 1.50
bare ground 0.50 1.00
grass 0.35 0.50
vegetation 0.25 0.35
Page 18 of 65 Storm Sewer Design Criteria
For storm sewers, time of concentration for other analysis points shall
be the highest time of concentration of the previous upstream
contributing area(s)plus time of flow in the pipe. For drainage areas of
one acre or less the time of concentration need not be calculated and a
storm duration of 10 minutes for mostly impervious area or 15 minutes
for mostly pervious area may be used as the basis of design.
c. Rainfall Intensity
The time of concentration of the runoff will be used to determine the
rainfall intensity component of the Rational Method Formula. The
rainfall intensity shall be computed as follows:
I=b/(Tc+d)^ e
where: I=Rainfall intensity(in/hr)
Tc=Time of Concentration(min)
b, d, e=Coefficient pert table below
COEFFICIENT 100-YEAR 50-YEAR 25-YEAR 10-YEAR 5-YEAR 3-YEAR
Tc<=60 min
b 90.8 107.0 98.5 107.9 92.9 90.6
d 16.5 21.1 24.0 23.6 19.7 19.5
e 0.685 0.734 0.729 0.781 0.788 0.803
T>60 min
b 84.0 _ 86.5 89.2 96.6 70.1 71.0
d 11.0 10.0 10.4 17.2 7.7 8.4
e 0.679 0.709 0.736 0.770 0.752 0.774
d. Sample Calculation Forms
Appendix A has a sample calculation form for storm sewer systems.
5.5.2 Design of Storm Sewers
A. Design Frequency
a. Newly Developed Areas
The design storm event for sizing storm sewers will be a 3-year rainfall.
The storm sewer should be designed so that the design hydraulic grade
Page 19 of 65 Storm Sewer Design Criteria
line shall be at or below the curb gutter grade for a curb and gutter
section, and six inches below the shoulder of a roadside ditch section.
For major thoroughfares,the design storm event will be a 5-year rainfall.
b. Redevelopment or In-fill Development
The existing storm drainage system will be evaluated using a 3-year
rainfall, assuming no development takes place. The same system will
then be evaluated with the development in place. Modifications to the
existing drainage system are to be considered based on the following:
1. If the proposed redevelopment has a lower or equal runoff
potential,no modifications to the existing storm drainage system
are required.
2. If the hydraulic gradient of the affected existing storm drainage
system is below the curb gutter grade (or six inches below the
shoulder of a roadside ditch section), no improvements to the
existing storm drain are required.
3. If the hydraulic gradient is above the gutter grade(or the edge of
shoulder of a roadside ditch section), the drainage system must
be analyzed for the impact of the 100-year storm event. If the
100-year event is at or below one foot below the floor levels of
adjacent existing habitable structures and exceeds the top of curb
(or the centerline elevation in a roadside ditch section)by twelve
inches or less, no improvements to the existing system are
required.
If none of these conditions are met by the proposed development
changes, improvements to the existing system will be required.
In all cases of improved development(development which increases the
runoff potential of the site), mitigation in the form of onsite or offsite
detention must be either purchased or provided.
c. City of Pearland Projects (Capital Improvement Programs)
Proposed City of Pearland Capital Improvements Program may indicate
that a larger diameter storm sewer is planned in the area proposed for
drainage improvements. The City Engineer will provide information on
planned capital improvements and should be consulted as to its impact
on new development.
Page 20 of 65 Storm Sewer Design Criteria
d. Private Drainage Systems
Drainage facilities draining private areas shall be designed in
conformance with appropriate design standards. The City of Pearland
will not approve nor accept for maintenance a drainage system on
private property unless it drains public water and is located in a drainage
easement. The connection of any storm sewer, inlet, or culvert to a
public drainage facility will be reviewed and approved by the City of
Pearland. Stormwater shall not be discharged or flow over any public
sidewalk or adjoining property except to existing creeks,ditches,streets,
or storm sewers in public rights of way or easements. Drainage to an
existing Texas Department of Transportation (TxDOT) ditch, road, or
storm sewer, must be approved or documented with a permit, letter or
note of no objections by TxDOT to the plan. Similarly, drainage to an
existing BDD4 ditch/creek must be approved or documented with a
permit, letter or note of no objections by BDD4 to the plan.
B. Velocity Considerations
a. Minimum velocities should not be less than 3 feet per second with the
pipe flowing full,under the design conditions.
b. Maximum velocities should not exceed 8 feet per second without use of
energy dissipation before release to natural or cultivated grass channels.
C. Pipe Sizes and Placement
a. Use storm sewer and inlet leads with at least 18-inch inside diameter or
equivalent cross section. Box culverts shall be at least 2' x 2'. Closed
conduits(circular,elliptical,or box)shall be selected based on hydraulic
principals and economy of size and shape. For inlets and leads carrying
5 cfs or more, 24-inch inside diameter is the minimum.
b. Larger pipes upstream should not flow into smaller pipes downstream
unless construction constraints prohibit the use of a larger pipe
downstream, the improvements are outfalling into an existing system,
or the upstream system is intended for use in detention.
c. Match crowns of pipe at any size change unless depth constraints or
other conditions justify matching flowlines.
Page 21 of 65 Storm Sewer Design Criteria
d. Locate storm sewers in public street rights-of-way or in approved
easements of adequate width. Back lot and side lot easements are
discouraged and must be justified.
e. Follow the alignment of the right-of-way or easement when designing
cast in place concrete storm sewers.
f. A straight line shall be used for inlet leads and storm sewers.
g. Center all culverts <48" within storm sewer easements wherever
possible.
h. Cast-in-place concrete storm sewers are not allowed within the public
right-of-way.
D. Starting Water Surface and Hydraulic Gradient
a. The hydraulic gradient shall be calculated assuming the top of the outfall
pipe as the starting water surface elevation when the total time of
concentration for the project drainage system is less than 30% of the
time of concentration of its outfall waterway. When the total time of
concentration for the project drainage system is greater than 30%of the
time of concentration for its outfall waterway, a comparison between
the 3-year water surface elevation of the receiving stream and the soffit
of the outfall pipe must be made. In that instance, whichever value is
higher shall be used as the starting tailwater condition.
b. At drops in pipe invert, should the upstream pipe be higher than the
hydraulic grade line, the hydraulic grade line shall be recalculated at a
value of 80% of the upstream pipe diameter above the downstream
flowline of the upstream pipe.
c. For the 3-year design storm, the Hydraulic Grade Line (HGL) shall at
all times be below the gutter line for all newly developed areas. In major
thoroughfares, the 5-year stormwater surface elevation shall be below
the gutter line.
d. For an extreme event (100-year) analysis, a comparison between 10-
year water surface elevation of receiving stream/detention pond and the
soffit of the outfall pipe must be made. In that instance,whichever value
is higher shall be used as the starting tailwater condition.
Page 22 of 65 Storm Sewer Design Criteria
e. The design engineer can also use a stage/time variable tailwater
developed from effective HEC-RAS and HEC-HMS model for extreme
event analysis.
f. For the 100-year design storm,the maximum depth of ponding allowed
will be 9-inches above top of curb for minor collector and local streets,
and 3-inches above top of inside curb for major and secondary
thoroughfare roads which is also known as one lane passable criteria.
E. Manhole Locations
a. Use manholes for precast conduits at the following locations:
(1) Size or cross section changes.
(2) Inlet lead and conduit intersections.
(3) Changes in pipe grade.
(4) Street intersections.
(5) A maximum spacing of 600 feet measured along the conduit run.
(6) Manholes and inlets shall not be located in driveway areas.
F. Inlets
a. Locate inlets at all low points in gutter.
b. Valley gutters across intersections are not permitted without approval
from the City Engineer.
c. Inlet spacing is a function of gutter slope, contributing drainage area,
and ponding width and height. For minimum gutter slopes,the
maximum spacing of inlets shall result in a gutter run of 350 feet from
high point in pavement,with a maximum total of 700 feet of pavement
draining towards any one inlet.
d. Use the following standard inlets as detailed in standard details:
Inlet Application Capacity
Type A Parking Lots/Small Areas 2.5 cfs
Type B-B Residential/Commercial 5.0 cfs
Type C Residential/Commercial 5.0 cfs
Type D Parking Lots 2.0 cfs
Type E Roadside Ditches 20.0 cfs
Page 23 of 65 Storm Sewer Design Criteria
e. Do not use `Beehive" grate inlets or other "specialty" inlets without
approval from City Engineer.
f. Do not use grate top inlets in unlined roadside ditches.
g. Place inlets at the end of proposed pavement, if drainage will enter or
leave pavement.
h. Do not locate inlets adjacent to esplanade openings.
i. Place inlets on side streets intersecting major streets, unless special
conditions warrant otherwise.
j. For lots 65' in width or greater,place inlets at mid lot.
G. Outfalls
Storm sewer and open street ditch outfalls to Brazoria Drainage District No
4 or Harris County Flood Control District ditches shall be per BDD4or
HCFCD criteria, as approved by the District and City Engineer.
5.5.3 Consideration of Overland Flow
All storm drainage designs will take into consideration the overland flow of runoff
to account for the possibility of system inundation, obstruction, failure, or events
that exceed the design storm. A representation of the overland flow scheme must
be submitted with the system design.
A. Design Frequency
The design frequency for consideration of overland sheet flow will focus on
extreme storm events which exceed the capacity of the underground storm
sewer system resulting in ponding and overland sheet flow through the
development to the primary outlet or detention basin. Unless otherwise
accepted by the City Engineer, the default storm event for this type of
analysis is the 100-year storm.
B. Relationship of Structures to Street
Per the City's Flood Hazard Prevention Ordinance, the lowest finish floor
elevation shall be a minimum of 12 inches above the 100-year base flood
elevation or 12 inches above the top of curb of the street.
Page 24 of 65 Storm Sewer Design Criteria
C. Calculation of Flow
a. Streets will be designed so that consecutive high points in the street will
provide for a gravity flow of sheet flow drainage to the ultimate outlet.
b. Sheet flow between lots will be provided only through a defined
drainage easement, through a separate instrument, or on the plat.
c. A map shall be provided to delineate extreme event flow direction
through a proposed development and how this flow is discharged to the
primary drainage outlet or detention basin.
d. In areas where ponding occurs and no sheet flow path exists, then a
calculation showing that runoff from the 100-year event can be
conveyed(or stored) and remain in compliance with the other terms of
this paragraph must be provided.
e. Selective reaches of the proposed storm sewer may need to be increased
in size to adjust the elevation of the 100-year HGL to not exceed the
desired HGL with respect to roadway top of curb.
f. Analysis using the Stormwater Management Model (XP-SWMM) will
be acceptable to the City.
5.5.4 Design of Roadside Ditches
Open ditch subdivisions and asphalt streets are prohibited unless in an area
conforming with "RE" zoning as specified in the City's Land Use and Urban
Development Ordinance or unless a variance has been granted by the City. In either
of these exceptions,the following shall apply to the design of roadside ditches.
A. Design Frequency
a. The design storm event for the roadside ditches shall be a 3-year rainfall.
b. The 3-year storm design capacity water surface elevations for a roadside
ditch shall be no higher than six inches below the edge of shoulder or
the natural ground at the right-of-way line,whichever is lower.
c. The design must include an extreme event analysis to indicate that
habitable structures will not be flooded.
B. Velocity Considerations
Page 25 of 65 Storm Sewer Design Criteria
a. For grass lined sections, the maximum design velocity shall be 3.0 feet
per second during the design event.
b. A grass lined or unimproved roadside ditch shall have side slopes no
steeper than three horizontal to one vertical.
c. Minimum grades for roadside ditches shall be 0.1 foot per 100 feet
(0.1%)unless approved by the City Engineer.
d. Calculation of velocity will use a Manning's roughness coefficient of
0.035 for improved earthen sections and 0.025 for ditches with paved
inverts.
e. Use erosion control methods acceptable to the City of Pearland when
design velocities are expected to be greater than 3 feet per second.
C. Culverts
a. Culverts will be placed at all driveway and roadway crossings and other
locations where appropriate.
b. Culverts may not be extended across property frontage to cover the
roadside ditch except for driveways.
c. Culverts will be designed assuming either inlet control or outlet control,
whichever the situation dictates.
d. Roadside culverts are to be sized based on drainage area. Calculations
are to be provided for each block based on drainage calculations.
Headlosses in culverts shall conform to TxDOT Hydraulics Manual.
e. Cross open channels with roadside culverts no smaller than 18 inches
inside diameter or equivalent. The size of culvert used shall not create
a headloss of more than 0.20 feet greater than the normal water surface
profile without the culvert.
f. Stormwater discharging from a ditch into a storm sewer system must be
received by use of an appropriate structure (i.e., stubs with ring grates
or type "E" inlet manholes).
D. Depth and Size Limitations for Roadside Ditches
Page 26 of 65 Storm Sewer Design Criteria
The use of roadside ditch drainage systems is stipulated by other City
development codes. When the use of open ditch drainage systems is
approved,the following shall apply to the design of roadside ditches:
a. Roadside ditches shall drain streets and adjacent land areas.
b. Residential Streets -The maximum depth of proposed roadside ditches
will not exceed 4 feet from centerline of pavement.
c. Commercial and Thoroughfare Areas - The maximum depth of
proposed roadside ditches will not exceed 4 feet from edge of roadway.
d. Roadside ditch bottoms should be at least 2 feet wide, unless design
analysis will support a narrower width.
e. Roadside ditch in slopes shall be set at a ratio of 3:1 or flatter.
f. Ditches in adjoining and parallel easements shall have the top of bank
not less than 2 ft. from the outside easement line.
g. The minimum street right-of-way for open ditch drainage in residential
developments shall be 80 feet in width. Rights-of-way shall be wider
for deep ditches. The minimum open-ditch section roadway shall be 24
feet pavement with 6 feet shoulders on each side.
5.5.5 Design of Outfall Pipes
Outfall design shall conform to BDD4rules or HCFCD Criteria,as appropriate,and
as approved by the City Engineer and the Drainage District. Section 5.6 of this
Manual generally incorporates these two counties' rules and/or criteria and shall
apply to all channel and detention designs subject to their requirements.
Pipe discharges of stormwater into earthen channels shall not exceed 5 feet per
second.
5.5.6 Stormwater Mitigation Detention Alternatives
Detention basin design shall conform to City of Pearland criteria, BDD4 rules, or
HCFCD criteria on a case-by-case basis as approved by the office of the City
Engineer. The City of Pearland detention design criteria appear in Section 5.8 of
this Manual.
Page 27 of 65 Storm Sewer Design Criteria
5.6 HYDROLOGIC ANALYSIS OVERVIEW
The selection of an appropriate hydrologic methodology for all projects shall be carried out
in accordance with Figure 5.6-1. The design engineer should contact the appropriate
reviewing agencies prior to preparing his analysis to obtain approval of the selected
methodology.
HEC-HMS was created at the U.S. Army Corps of Engineers (USACE) Hydrologic
Engineering Center (HEC). Please note that a rainfall runoff analysis using HEC-HMS
should only be used in cases where it is required for FEMA submittals or where a reviewing
agency has determined that the design engineer must investigate the downstream impacts
of the proposed project. In any case, for projects requiring FEMA approval, design
engineers should use the most current effective model of the study stream.
5.6.1 Peak Discharge Determination
For areas draining less than 200 acres,the natural, existing and proposed discharge
rates can be determined by the Engineer using the Rational Method Formula, Q=
CIA, where C is the runoff coefficient, I is the rainfall intensity, and A is the
drainage area. See Section 5.5.1C of this manual for the application of this method.
5.6.2 Hydrograph Development for Small Watershed(Small Watershed Method)
The small watershed method referred to is the one developed by H.R.Malcolm and
is described below.
A. Introduction
A technique for hydrograph development which is useful in the design of
detention facilities serving relatively small watersheds has been presented
by H.R. Malcolm. The methodology utilizes a pattern hydrograph which
peaks at the design flow rate and which contains a runoff volume consistent
with the design rainfall. The pattern hydrograph is a two-part function
approximation to the dimensionless hydrograph proposed by the Bureau of
Reclamation and the Soil Conservation Service.
B. Equations
The Small Watershed Hydrograph Method consists of the following
equations:
Page 28 of 65 Storm Sewer Design Criteria
V
TP =
1.39Qp (1)
Qr tet; for ti 2
q, = 2 1-cos T 1 P ( )
-1.30t,/
q. = 4.34QP e TP for t;> 1.25TP (3)
* Calculator must be in radian mode.
where TP is the time (in seconds)to QP, Q, is the peak design flow rate (in
cubic feet per second)for the subject drainage area, V is the total volume of
runoff(in cubic feet) for the design storm, and ti and q; are the respective
time (s) and flow rates (cfs) which determine the shape of the inflow
hydrograph. All variables must be in consistent units.
C. Applications
The peak flow rate,Qp,is obtained from the Rational Method Formula. For
detention mitigation analyses the Rational Method should be applied in
accordance with Section 5.5.1.0 of this manual, with the exception that all
proposed developed runoff coefficients (C) given in that section should be
inflated by 5%. The total volume of runoff(V) is the same as the rainfall
excess. Table 5.6-1 below gives typical values for the rainfall excess based
on percent impervious cover. The actual values may be interpolated from
the table. See Table 5.6-3, Section 5.6.3.3, for determination of percent
impervious cover.
Table 5.6-1. Typical Rainfall Excess Values
To Be Used with Small Watershed Method
100-Year 10-Year 3-Year
Impervious Cover Rainfall Excess(in) Rainfall Excess(in) Rainfall Excess(in)
100% 13.5 8.3 6.1
90% 13.2 8.0 5.7
80% 13.0 7.8 5.4
70% 12.7 7.5 5.2
60% 12.4 7.3 5.0
50% 12.2 7.0 4.8
45% 12.0 6.9 4.7
40% 11.9 6.8 4.6
35% 11.8 6.7 4.5
Page 29 of 65 Storm Sewer Design Criteria
30% 11.6 6.6 4.4
20% 11.4 6.3 4.2 _
10% 11.1 6.1 4.0
0% 10.8 5.9 3.8
The Small Watershed Hydrograph Method should only be used where an
impact analysis is not required for the total drainage system including the
detention facility and outfall channel as indicated in Figure 5.6-1. The
Small Watershed Hydrograph Method cannot be used in conjunction with
the HEC-HMS models of watersheds studied in the Flood Insurance Study.
The time to peak of the Small Watershed Hydrograph Method is computed
strictly to match volumes and has no relationship to the storm durations and
rainfall distributions used in the Flood Insurance Study.
Figure 5.6-1.
Hydrologic Method 1 I
Determination-Mitigation Analysis l 1
1 1
Methode,ogy I 5 Inquire About
YES I ■.y' Eligibility la i i i+ Use Appendix A
■■■ Must be Aeteptabk I Methodology to FEMA Purchasing Regional I
Detention
NO4 *140
Use Small
YF�S Use g.65 ee4t
YES hlet,,naobgy ■ •� Per Aa Site letlel Watershed Herrod I
1.1* Must be Acceptable Per Sectlm l32
to Reviewing Agency
NO
,+.NO y
5.6.3 Watershed Modeling
In October of 2001, through a joint effort between FEMA and HCFCD, Harris
County began the Tropical Storm Allison Recovery Project (TSARP). TSARP
models for Clear Creek simulated the existing conditions in Clear Creek Watershed
when released in June 2007. The effective models for Clear Creek watershed can
be downloaded from the HCFCD Model and Map Management website at
www.m3models.org. Design engineers should always use the current effective
model when FEMA approval is required.
Page 30 of 65 Storm Sewer Design Criteria
In the case that FEMA approval is not required for the project, design engineers
should use the methodology presented in this Chapter to design drainage facilities
in the City of Pearland.
A. Rainfall Frequency and Duration
The storm event used to establish regulatory flood plain and floodway limits
in the Flood Insurance Study is the 100-year, 24-hour event. For planning
purposes and establishing flood insurance rate zones the 10-, 50-, and 500-
year events also require analysis. For projects requiring FEMA submittals,
the rainfall depths in the most current effective model should be used. For
all other projects requiring a rainfall runoff analysis, the depths should be
based on Table 5.6-2, which includes the maximum values for each depth,
duration and frequency from the TSARP,TP40 and Hydro 35 information.
Point rainfall amounts for various durations and frequencies for use in the City are
given in Table 5.6-2.
Table 5.6-2. Point Rainfall Depth (Inches)Duration-
Frequency Values1
Depth(in)
100- 25- 10- 5- 3-
Duration Year Year Year Year Year
5 min. 1.20 1.00 0.90 0.80 0.70
30 min. 3.00 2.4 2.10 1.90 1.60
1 hr. 4.3 3.4 _ 2.90 2.50 2.20
2 hr. 5.7 4.4 3.70 3.10 2.60
3 hr. 6.8 5.1 4.20 3.50 2.80
6 hr. 9.10 6.6 5.30 4.40 3.30
12 hr. 11.10 8.00 6.40 5.30 4.00
24 hr. 13.50 9.80 7.80 6.40 4.80
B. Rainfall Depth-Area Relationship and Temporal Distribution
The version of HEC-HMS that was available at the time of the TSARP does
not have an option for depth-area indices for watersheds larger than 10
square miles. Therefore, it was decided to use point rainfall depths to
specify the hypothetical rain events used in the hydrologic analyses. For
projects requiring FEMA approval, the rainfall input of the most current
'Source: TP-40,Hydro-35 and U.S.G.S.
Page 31 of 65 Storm Sewer Design Criteria
effective model should be used. For projects not requiring FEMA
submittals,point rainfall depths should be used.
The version of HEC-HMS that was available at the time of the TSARP
allows the user to shift the peak of the storm from 50%of the storm duration
to 25%, 33%, 67%, or 75% of the storm duration. For projects requiring
FEMA approval,the rainfall input of the current effective model should be
used. For projects not requiring FEMA submittals, the 67% duration
peaking temporal rainfall distribution should be used see Exhibit 6-1.
C. Loss Rates
Rainfall excess and runoff volume are dependent on factors such as rainfall
volume, rainfall intensity, antecedent soil moisture, impervious cover,
depression storage, interception, infiltration, and evaporation. The extent
of impervious cover and depression storage is actually a measure of
development and is discussed in the next section. The other factors are
dependent on soil type,land use,vegetative cover,topography,time of year,
temperature, etc.
For projects requiring FEMA approval, the loss input in the most current
effective model should be used. For all other projects requiring a rainfall
runoff analysis,the Green-Ampt loss function available in HEC-HMS shall
be used. A detailed description of the Green-Ampt loss function can be
found in USACE EM 1110-2-1417. The following parameters should be
used to compute the Green-Ampt losses:
Initial Loss = 0.1 inches
Volume Moisture Deficit = 0.385
Wetting Front Suction = 12.45 inches
Hydraulic Conductivity = 0.024 in/hr
Additional development in the watershed is analyzed by increasing the
value of the impervious cover parameter in the runoff model. Table 5.6-3
gives appropriate values of percent impervious based on land use types:
Table 5.6-3.Percent Impervious Cover For Land Use Types
Land Use %Impervious
High Density 85%
Dry Detention Ponds 85%
Undeveloped 0%
Page 32 of 65 Storm Sewer Design Criteria
Developed Green Areas 15%
Residential Small Lot
(<1/4 acre or schools) 40%
Residential Large Lot
(>1/4 acre or older neighborhoods with
limited roadside ditch capacity) 20%
Residential Rural Lot
(>5 acre ranch or farm) 5%
Isolated Transportation 90%
Water 100%
Light Industrial 60%
Airport 50%
5.6.4 Unit Hydrograph Methodology
The model for the Clear Creek Watershed flood insurance study is based on the
Clark unit hydrograph. In cases where FEMA submittals are required, the design
engineer should use the Clark unit hydrograph method. In other cases, where a
downstream impact analysis is required,consult the appropriate reviewing agencies
on the applicability of the Clark unit hydrograph. In some cases, other unit
hydrograph methods may be applicable.
The watershed parameters for the Clark unit hydrograph may be developed using
the Harris County methodology. Design engineers should refer to the current
effective model available on HCFCD Model and Map Management Website(http://
http://www.m3models.org/) and the most recent version of the HCFCD hydrology
manual.
5.6.5 Flood Hydrograph Routing
Flood routing is used to simulate the runoff hydrograph movement through a
channel or reservoir system. Flood routing techniques vary greatly between
hydrologic computer models and caution should be used in selecting a routing
method, which adequately represents the channel storage conditions present in
areas with extremely flat slopes, such as within the City of Pearland.
The HEC-HMS program employs several flood routing methods for characterizing
the transfer of the runoff hydrograph through the drainage system of a watershed.
The models developed for the Flood Insurance Study for the Clear Creek watershed
use the Modified Puls Method of routing. This flood routing method is based on
the continuity equation and a relationship between flow and storage or stage. The
routing is modeled on an independent-reach basis from upstream to downstream.
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A detailed discussion of the Modified Puls Method can be found in the user's
manual for HEC-HMS.
A. Storage—Routing Computations Using HEC-RAS
All of the Flood Insurance Study data submitted for the Clear Creek
Watershed have utilized the HEC-RAS computer program to generate the
storage-discharge relationship required for HEC-HMS to utilize the
Modified Puls flood routing. Listed below is a suggested procedure by
which the HEC-RAS program can best be formatted to provide the most
effective input and output data necessary for hydrologic studies.
a. Determine which routing reaches of the subject channel will need to be
evaluated. Routing reaches that are defined in the Flood Insurance
Study usually represent an area between outfalls of two significant
drainage areas.
b. Review all the available data for the routing reaches of the subject
stream.
c. Run HEC-HMS for the 100-year storm event using preliminary channel
routing data or alternate methods(i.e. Muskingum or Lag).
d. Use the effective model to determine the 100-year flows for the stream
in question. Multiply the preliminary 100-year peak discharges
determined above by 0.20, 0.40, 0.60, 0.80, 1.00, 1.20, and 1.50 to
obtain a series of seven discharges for each storage routing reach.
e. The discharges that have been developed are then input to the HEC-
RAS program. The discharges should be held constant throughout the
subject routing reach. Outflows through a routing reach should not vary.
f. Obtain storage outflow data calculated using HEC-RAS utilizing the
most upstream and downstream cross section of the reach.
g. Determine the average flood wave travel time along the reach. To
calculate the average wave travel time, divide reach travel time by a
flood wave velocity factor of 1.5.
h. Determine the number of subreaches to be used in the HEC-HMS
computations. Determine this number by dividing the average flood
wave travel time along the reach by the HEC-HMS computational time
step for each of the flows entered in the HEC-RAS model.
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i. Run the HEC-HMS model.
j. Cycle (or balance) the HEC-HMS and HEC-RAS until the 1%
exceedance probability (100-year) flows at the downstream end of the
routing reach match within 5%.
The HEC-RAS model used in the storage-outflow analysis should be
reviewed to ensure that the analysis is correctly determining the total storage
volume. Make sure that the ineffective flow areas are modeled
appropriately.
5.7 HYDRAULIC CHANNEL DESIGN CRITERIA
5.7.1 Introduction
The hydraulic design of a channel or structure is of primary importance to ensure
that flooding and erosion problems are not aggravated or created. This section
summarizes methodologies, procedures, and criteria which should be used in the
hydraulic analysis of the most common design problems in City of Pearland and
Brazoria County, Texas. In some instances, methodologies and parameters not
discussed in this section may be required. When an approach not presented herein
is required, it should be reviewed early on with the office of the City Engineer.
A. Design Frequencies
All the City of Pearland open channels will be designed to contain the runoff
from the 100-year frequency storm within the right-of-way, except where
channel improvements are necessary to offset increased flows from a
proposed development. In those cases, the 100-year flood profile under
existing conditions of development should not be increased.
In areas served by closed systems, stormwater runoff should be removed
during the 100-year frequency storm without flooding of structures. This is
accomplished through the design of the street system, the storm sewer
system, and other drainage/detention systems.
B. Required Analysis
In designing a facility for flood control purposes, a hydraulic analysis must
be conducted which includes all the factors significantly affecting the water-
surface profile or the hydraulic grade line of the proposed facility. For open
channels, the primary factors are losses due to friction, constrictions,
Page 35 of 65 Storm Sewer Design Criteria
bridges, culverts, confluences, transitions, and bends. The design of
channels or conduits should generally minimize the energy losses caused by
these factors which impede or disrupt the flow. Factors affecting the
hydraulic grade line in closed conduits are entrance losses, friction losses,
exit losses, and bend losses.
C. Acceptable Methodologies
Several methods exist which can be used to compute water-surface profiles
in open channels. The methodology selected depends on the complexity of
the hydraulic design and the level of accuracy desired. Peak discharges and
discharge hydrographs developed using one of the methodologies described
in Section 5.6 must be incorporated into the existing effective HEC-RAS
model in order to determine the impact of any proposed development flood
control facility on the entire channel system.
For the design of proposed channel with flow confined to uniform cross-
sections, either a hand calculated normal depth or direct step computation
is sufficient. Manning's equation should be used for computing normal
depth. For designing a non-uniform proposed channel with flow in the
overbanks, the use of HEC-RAS is recommended. Any proposed channel
improvements to an existing collector ditch or creek within the jurisdiction
of the City must be modeled using HEC-RAS and incorporated into the
model used in the Flood Protection Plan.
Bridges, culverts, and expansion and contraction losses are taken into
account in the HEC-RAS computer program. If these losses are significant
and the normal depth or direct step method is employed,the losses must be
included in the backwater calculations. Design criteria for bridges,culverts,
transitions,bends and drop structures are presented in the remainder of this
section.
5.7.2 Open Channel Design
A. Location and Alignment
The first step in designing or improving an open channel drainage system
is to specify its location and alignment. Good engineering judgment must
be incorporated to insure the proposed channel location provides maximum
service to an area while minimizing construction and maintenance costs.
General factors and the City of Pearland criteria which should be taken into
account in locating improved channels are as follows:
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a. Follow existing channels, ditches, swales, or other low areas in
undeveloped watersheds. This will minimize the cost of the channel
itself and the underground storm sewer system and will allow for
overland flow to follow its natural drainage pattern.
b. For safety reasons, channels and roads must not be located adjacent to
one another. Should such a conflict appear unavoidable,the design must
be approved by the office of the City Engineer.
c. The angle at which two channels intersect must be 90 degrees or less
(angle measured between channel centerlines on upstream side on point
of intersection).
d. The minimum radius of curvature for unlined channel bends is three
times the ultimate channel top width, and the maximum bend angle for
both lined and unlined sections is 90 degrees. Bend losses and erosion
protection must be included in the hydraulic analysis of severe curves.
B. Existing Cross Sections
For determining existing flood profiles, both the channel section and
overbank areas must be used in the hydraulic calculations. Channel sections
must be based on a recent field survey. In some cases, the City of Pearland
may have recent channel improvements information which can be utilized.
Plans of previous channel improvements should only be used for very
preliminary analysis. Overbank areas are best defined by field surveys,but
this is not always practical or economically justified. Elevations in the flood
plain beyond the limits of the channel can be obtained from the best
topographic information available for the study reach.
When designing a channel improvement, the channel sections used should
extend beyond the City of Pearland right-of-way a reasonable distance. The
purpose of including elevations beyond the right-of-way is to avoid a design
which creates ponding adjacent to the right-of-way a reasonable distance
and depends on the adjacent terrain, but in no case shall it be less than 20
feet.
C. Typical Design Sections
Typical channel sections have been established which should be used in
designing improved channels. Minimum dimensions are based on
experience of constructing and maintaining channels.
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For some applications,other cross section configurations may be necessary.
A proposed cross section different from the typical sections presented
should be reviewed with the office of the City Engineer for approval before
proceeding with design or analysis.
a. Earthen Channels
The following are minimum requirements to be used in the design of all
earthen channels:
1. Maximum earthen side slopes should be 4 (horizontal) to 1
(vertical). Slopes flatter than 4:1 may be necessary in some
areas due to local soil conditions. For channels and detention
reservoirs 6 feet deep or greater, side slopes selection shall be
supported by geotechnical investigations and calculations.
2. Minimum bottom width is ten (10) feet unless approved by the
office of the City Engineer or BDD4.
3. A minimum maintenance berm is required on either side of the
channel of between 10 and 30 feet depending on channel size as
depicted in Table 5.7-1A and 5.7-1B.
These criteria and regulations shall be applicable for all channels that
will be accepted for maintenance by BDD4or HCFCD. Small channels
on private property, not draining public water, that do not conform to
these criteria shall remain the responsibility of the owner. These private
small channels within the City of Pearland and road-side ditches along
City streets shall be designed in accordance with Section 5.5.
TABLE 5.7-1A
KEY TO EASEMENT REQUIREMENTS
CHANNEL CHANNEL BOTTOM WIDTH [feet]
DEPTH [feet] 6 8 10 12 15 20 30 40
4 A A B B B B C C
6 A A B B B B C C
8 B B B C C C C C
10 C C C C C C C C
12 C C C D D D D D
14 D D D D D D D D
16 D DD D D D D D
18 D D D D D D D D
Page 38 of 65 Storm Sewer Design Criteria
TABLE 5.7-1B
ULTIMATE MAINTANENCE REQUIREMENTS FOR CHANNELS
KEY TOTAL BERM BERM WIDTH BERM WIDTH
VALUE WIDTH [feet] EACH SIDE [feet] UNEVEN [feet]
Side 1 Side 2
A 30 15 20 10
B 40 20 25 15
C 50 25 30 20
D 60 30 30 30
Larger maintenance berms may be required due to the future needs of
an ultimate channel. Right-of-way requirements for all main outfall
channels are included in the Brazoria Drainage District No 4 Flood
Protection Plan.
1. Backslope drains or interceptor structures are necessary at a
minimum of 1,000 feet intervals to prevent sheet flow over the
ditch slopes.
2. Channel slopes must be re-vegetated immediately after
construction to minimize bank erosion.
3. Flow from roadside ditches must be conveyed to the channel
through a roadside ditch interceptor and pipe.
b. Concrete-Lined Trapezoidal Channels
In instances where flow velocities are excessive, channel confluences
create a significant erosion potential,or right-of-way is limited, fully or
partially concrete lined channels may be necessary. The degree of
structural analysis required varies significantly depending on the
intended purpose and the steepness of the slope on which paving is
being placed. Slope paving steeper than 3:1 shall be designed based on
a geotechnical analysis that addresses slope stability and groundwater
pressure behind the paving.
The following are minimum requirements for partially or fully concrete
lined trapezoidal channels:
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1. All slope paving should include a minimum 24-inch toe wall (9
inches thick)at the top and sides and a 48-inch toe wall(9 inches
thick)across or along the channel bottom for clay soils.
2. Fully lined cross-sections should have a minimum bottom width
of eight(8) feet.
3. Concrete slope protection placed on 3:1 slopes should have a
minimum thickness of 4 inches and be reinforced with #3 bars
on 18-inch centers both ways.
4. Concrete slope protection placed on 2:1 slopes should have a
minimum thickness of 5 inches and be reinforced with #3 bars
on 15-inch centers both ways.
5. Concrete slope protection placed on 1.5:1 slopes should have a
minimum thickness of 6 inches and be reinforced with #4 bars
on 18-inch centers both ways. Poured in place concrete side
slopes should not be steeper than 1.5:1.
6. In instances where the channel is fully lined, no backslope
drainage structures are required. Partially, lined channels will
require backslope drainage structures.
7. Weep holes may be required to relieve hydrostatic head behind
lined channel sections. Check with the geotechnical
investigation report.
8. Where construction is to take place under conditions of mud
and/or standing water, a seal slab of Class C concrete should be
placed in channel bottom prior to placement of concrete slope
paving.
9. For bottom widths of twenty (20) feet and greater, transverse
grade beams shall be installed at twenty (20) feet spacing on
center. Grade beams shall be one foot wide,one foot-six inches
deep, and run the width of the channel bottom.
c. Rectangular Concrete Pilot Channels(Low Flow Sections)
In limited right-of-way, it is sometimes necessary to have a vertical
walled rectangular section. Presented below are minimum requirements
for rectangular concrete pilot channels:
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1. The structural steel design is based on Grade 60 steel. This
should be confirmed by a design check based on local soil
conditions.
2. Minimum bottom width should be eight(8) feet to allow for
maintenance.
3. For bottom widths twelve (12) feet or greater, a center
depression is required.
4. For bottom widths twenty(20) feet or greater, transverse grade
beams shall be installed at twenty(20) feet spacing on center.
Grade beams shall be one foot wide, one foot-six inches deep,
and run the width of the channel bottom.
5. Minimum height of vertical walls should be four(4) feet.
Heights above this shall be in two (2) foot increments.
Exceptions shall be on a case by case basis.
6. Escape stairways shall be constructed. Escape stairways shall
be located at the upstream side of all street crossings, but not to
exceed 1,400 feet intervals.
7. For rectangular concrete pilot channels with earthen side
slopes, the top of the vertical wall should be constructed to
allow for future placement of concrete slope paving.
8. Weep holes should be used to relieve hydrostatic pressure.
9. Where construction is to take place under conditions of mud
and/or standing water, a seal slab of Class C concrete should be
placed in channel bottom prior to placement of concrete slope
paving.
10. Concrete pilot channels may be used in combination with slope
paving or a maintenance shelf. Horizontal paving sections
should be analyzed as one way paving capable of supporting
maintenance equipment.
11. A geotechnical investigation and report shall be performed.
Soil borings shall be obtained at a minimum of every 1,000 feet
to a depth of 1.5 times the proposed channel depth.
Page 41 of 65 Storm Sewer Design Criteria
D. Water-Surface Profiles
a. General
For steady, gradually varied flow conditions in natural or improved
open channels,the computational procedure known as the standard step
method is recommended for computing water-surface profiles. The
one-dimensional energy equation is solved by using an iterative
procedure to calculate a water-surface elevation at a cross section.
Manning's equation is used to compute energy losses due to friction
(Section 5.7.2.D.b),while losses due to obstructions and transitions are
calculated using the appropriate equations discussed in this chapter. For
cases where the flow is strictly uniform, as determined by the design
engineer, the standard step method can be reduced to a direct step
method or to a uniform flow computation.
The recommended computer program available for computing water-
surface profiles when using the standard step method is HEC-RAS. As
indicated previously,the City of Pearland prefers this program primarily
because it is widely accepted and the program readily facilitates the
design of channel improvements.
Good judgment must be exercised when determining cross-section
locations for water-surface profile calculations. Cross sections should
divide the channel into reaches, which approximate uniform flow
conditions. For example, closely spaced cross sections are required at
an abrupt transition such as a bridge, while relatively uniform channel
reaches with no significant changes in conveyance require fewer cross
sections. As a general guideline, the spacing should not exceed about
1,000 feet.
b. Manning's Equation
Manning's equation is an empirical formula used to evaluate the effects
of friction and resistance in open channels. For uniform flow conditions
where the channel bottom and energy line are essentially parallel,
Manning's equation should be used to compute the normal depth. For
gradually varied flow conditions, the slope of the energy line at a given
channel section should be computed using Manning's equation.
The equation is:
Page 42 of 65 Storm Sewer Design Criteria
2 1
1.49
Q = xAxRxS2
n
where Q=total discharge in cubic feet per second.
n=coefficient of roughness
A=cross-sectional area of channel in square feet
R=hydraulic radius of channel in feet
S = slope of energy line in feet per foot (same as
Channel bottom slope for uniform flow).
Channel and overbank sections may have to be subdivided to represent
differences in roughness across the section. Subdividing may also be
helpful in computing Manning's equation for natural,compound or non-
prismatic sections(References 5.3 (5, 9).
c. Manning's "n" Values
Manning's "n" values for design purposes should conform with Table
5.7-2. An "n" value of 0.04 for unlined channels represents a moderate
vegetal growth. For unlined channels, with a design flow larger than
10,000 cubic feet per second, "n" value of 0.035 may be used. For
existing, unimproved channels and overbank areas, "n" values should
be determined in accordance with References 5.3 (9, 10, 11, 12)
TABLE 5.7-2
MANNING'S "n"VALUES AND ALLOWABLE 25-YEAR
VELOCITIES FOR CHANNEL DESIGN
Roughness Average Maximum
Coefficient or Velocity Velocity
Manning's (Feet per (Feet per
Channel Description "n"Value Second) Second)
Unmaintained Earthen 0.05 3.0 5.0
Grass Lined:
Predominately Clay 0.045 3.0 5.0
Predominately Sand 0.045 2.0 4.0
Concrete Lined 0.015 6.0 10.0
Articulated Block 0.045 5.0 8.0
Overbanks and Existing See References Not Not
Unimproved Channels 5.3 (5) Applicable Applicable
d. Velocities
Page 43 of 65 Storm Sewer Design Criteria
Average and maximum allowable velocities based on 25-year flows are
given in Table 5.7-2. In the portion of Brazoria County where sandy
soils are known to exist, soils information may be needed to determine
the predominant type of soil and the corresponding allowable velocities
for unlined channels. Maximum velocities also apply to bridges,
culverts, transitions, etc. Where velocities exceed the maximum
allowed, erosion protection must be provided.
e. Flowline Slope
Maximum slopes are generally controlled by the maximum allowable
velocity. Channel slopes shall not be less than 0.05%.
f. Starting Water-Surface Elevations
For design of open channels, starting water-surface elevations at the
channel mouth will generally be based on the normal depth in the design
channel.
In determining actual flood profiles or flood plain delineation, the
water-surface elevation from the outfall channel should be projected
horizontally upstream until it intersects the flood profile on the design
channel. An assumption that the peaks occur at the same time will
generally produce a conservative flood profile. Otherwise, an analysis
of coincident flow may be conducted to determine the flow in the outfall
channel at the time the peak flow occurs on the design channel.
g. Headlosses
Manning's equation is used to estimate energy or headlosses due to
channel friction and resistance. Other sources of losses in open channels
include confluences, transitions, bends, bridges, culverts, and drop
structures. When computing water surface profiles either by hand or
with the help of a computer program, the engineer must include the
significant sources of headloss.
E. Confluences
The alignment of confluences is critical with regards to channel erosion and
energy losses caused by turbulence and eddies. The primary variables used
in designing channel junctions are angle of intersection, shape and
dimensions of the channel, flow rates, and flow velocities.
Page 44 of 65 Storm Sewer Design Criteria
The angle of intersection between the main channel and tributary channels
or storm sewers shall be 30 degrees. Outfalls or junctions perpendicular to
the receiving channel will create severe hydraulic problems, and therefore,
will not be allowed without approval by the office of the City Engineer.
Any protective lining must extend far enough upstream and downstream on
both channels to prevent serious erosion. The slope protection must be
carried up to at least the 10-year flood level in both channels. A good grass
cover must also be established from the edge of the protection to the top of
bank.
If the main channel flowline is lower than the side channel flowline, an
erosion control structure must be used in the side channel.
F. Transitions
a. Design
Transitions in channels should be designed to create a minimum of flow
disturbance and thus minimal energy loss. Transitions generally occur
at bridges or culverts,and where cross-sections change due to hydraulic
reasons or right-of-way restrictions. The transition can consist of either
a change in cross-section size or geometry.
All angles of transition should be less than 12 degrees (20 feet in 100
feet). When connecting trapezoidal and rectangular channels, the
warped or wedge type transition is recommended. If super-critical flow
conditions are encountered, standing waves, superelevation, and
hydraulic jumps must be considered.
b. Analysis
Expansion and contraction losses must be accounted for in backwater
computations. Transition losses are usually computed using the energy
equation and are expressed in terms of the change in velocity head from
downstream to upstream of the transition. The headloss between cross
sections is expressed by:
hL =CV2 2
2 —V—'
2g 2g
Page 45 of 65 Storm Sewer Design Criteria
where: hL=headloss (feet,
c=expansion or contraction coefficient
V2=average channel velocity of downstream section
(feet per second),
V1 = average channel velocity of upstream section
(feet per second), and
g=acceleration of gravity(32.2 ft/sec2).
Typical transition loss coefficients to be used in HEC-RAS are given
below:
Coefficient
Transition Type Contraction Expansion
Gradual or Warped 0.10 0.30
Bridge Sections,Wedge, or 0.30 0.50
Straight Lined
Abrupt or Squared End 0.60 0.80
When computing the backwater profile through a transition,engineering
judgment must be used in selecting the reach lengths. Smooth
transitions require fewer computation steps than the abrupt transitions.
G. Bends
a. Design
Channel bends or curves should be as gradual as possible to reduce
erosion and deposition tendencies. For channel bends with a radius of
curvature measured from the channel centerline of less than three times
the top width of the ultimate channel, slope protection is required. For
both lined and unlined channels,a 90 degree bend is the maximum curve
allowed. Erosion protection on bends must extend at least along and 20
feet downstream of the curved section on the outside bank. Additional
protection may be required on the channel bottom and inside bank, or
further downstream than 20 feet, if the channel geometry and velocities
indicates a potential erosion problem.
b. Analysis
Headlosses should be incorporated into the backwater computations for
bends with a radius of curvature less than three times the channel top
width. Energy loss due to curve resistance can be expressed as:
Page 46 of 65 Storm Sewer Design Criteria
hL=cf V2/2g
where: hL=headloss(feet),
cf.=coefficient of resistance,
V=average channel velocity(feet per second), and
g=coefficient of gravity(32.2 feet/second/second).
Guidelines for selecting cf can be found in Reference 5.3 (10).
HEC-RAS has the ability to incorporate a bend loss computation in
terms of a minor loss coefficient ranging from 0.0 to 1.0. If HEC-RAS
is used and bend losses are significant, the loss must be added at the
appropriate point in the minor loss table. Bends with a radius of
curvature greater than three times the top width of the channel generally
have insignificant losses and no computation is required.
5.8. DETENTION SYSTEM DESIGN
5.8.1 Introduction
In situations where on-site storage of stormwater runoff is the most effective way
to allow development of properties without increasing the flood potential
downstream, detention systems will be permitted. This section of the Manual
presents background information on stormwater storage techniques and detailed
guidelines and criteria for the design of stormwater storage facilities.
A. Types of Storage Facilities
The physical features of a particular site, as well as the type of development
proposed, will dictate, in many cases, the type of detention storage facility
that may be utilized. Since detention facilities are often designed to remain
dry, they can provide dual purpose functions such as parking lots and
recreational areas. In limited instances, on-site detention facilities have
been designed to be buried underground and thus are completely out of
sight.
All of these types of facilities are considered acceptable methods of
stormwater detention and can be designed hydraulically to accomplish the
intended purpose. All stormwater detention facilities are subject to periodic
Page 47 of 65 Storm Sewer Design Criteria
inspection by the City Engineer to insure proper construction and
maintenance.
Dual use of stormwater detention facilities is encouraged. However, when
a dual use is proposed, such as recreation, a joint use agreement is required
between the owner and the entity sponsoring the secondary use. This
agreement must outline the maintenance responsibilities of the entity and of
the owner and must be submitted to the City of Pearland for approval. For
privately maintained or dual use systems,each stormwater detention facility
will be reviewed and approved by the City only if the following assurances
can be provided:
a. Adequate storage is available to provide necessary peak flow reduction;
b. The facility will perform as designed over the expected life of the
project;
c. Provisions for maintenance, including long-term funding for
maintenance, are adequate to insure the facility does not detract from
the value of adjacent properties;
d. The facility will be maintained to operate long term and continue to
function as designed; and,
e. The stormwater detention pond should be designed to drain the
stormwater within 72 hours so as to provide storage room for the
following storm event.
Detention ponds may be either on-site or off-site facilities. An off-site
detention basin is defined as one that is located on a City of Pearland,
BDD4, or HCFCD ditch and is receiving runoff from areas significantly
larger than the development project under design. An on-site basin
generally receives runoff from a small drainage area consisting primarily of
one development project. In the discussions that follow,the design methods
presented are generally oriented to on-site detention facilities. Specific
reference will be made to methods for off-site facilities.
Projects located in the uppermost reach of a drainage basin may use the
volume of stormwater stored in pipes, ditches, or streets as credit for the
part of the detention requirement. Storage will be credited for street volume
up to the maximum allowable ponding depth per these criteria. Sheet flow
analysis must be performed to insure that for extreme events, the ponding
level in the streets will not exceed the maximum ponding level.
Page 48 of 65 Storm Sewer Design Criteria
B. Geotechnical Design
Before initiating final design of detention ponds over 6 feet deep and 2 acres
in size, a detailed soils investigation by a geotechnical engineer shall be
undertaken. Geotechnical investigation, at a minimum, the study should
address:
a. The ground water conditions at the proposed site;
b. The type of material to be excavated from the pond site and its suitability
for fill material;
c. If an embankment is to be constructed, adequate investigation of
potential seepage problems through the embankment and attendant
control requirements, the availability of suitable embankment material
and the stability requirements for the embankment itself;
d. Potential for structural movement on areas adjacent to the pond due to
the induced loads from existing or proposed structures and methods of
control that may be required; and,
e. Stability of the pond side slopes.
5.8.2 Hydrologic Design
Detention basin design shall conform to City of Pearland criteria, BDD4 rules, or
HCFCD criteria on a case-by-case basis as approved by the office of the City
Engineer. The hydrologic methods for detention design should be in accordance
with Section 5.6 of this Manual. The hydrologic design criteria for stormwater
mitigation is divided into three design categories based on the size of the
contributing drainage area.
Small Projects: less than 2 acres
Medium Project: 2 acres to 200 acres
Large Project: more than 200 acres
5.8.3 On-Site Facilities
A. Small Projects (Projects 2 Acres or Smaller)
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Small Projects are defined as those projects that are 2 acres or smaller. The
following criteria is applicable for the provision of detention mitigation
calculation:
a. For all small projects located adjacent to the BDD4 drainage system or
projects of any size directly outfalling into BDD4 drainage system
requires approval from BDD4.
b. Single Family Residential (SFR) lots of 12,000 Square feet or less and
located outside the FEMA delineated 100-Year Floodplain are exempt
from detention if proposed impervious cover is less than or equal to
75%. Grading and drainage plan is required to show no impact to the
neighboring property due to proposed site development. This provision
is not applicable for the subdivision in which bigger lots are divided into
smaller lots.
c. SFR lots with (12,000 SF > Area < 2 Acres) is required to provide
stormwater detention at a rate of 0.65 ac-ft/ac of increased
impervious cover. If the proposed impervious cover is less than 75%,
the project may be eligible for purchasing regional detention.
d. The SFR construction within FEMA mapped floodplain will not be
allowed to bring dirt from offsite and must be pier and beam
construction with the use of flood vent as mentioned in the FEMA
guideline.
e. Private parking areas, private streets, and private storm sewers may be
used for detention provided that the maximum depth of ponding does
not exceed 9 inches directly over the inlet, and the parking areas are
provided with signage stating that the area is subject to flooding during
rainfall events.
B. Medium Projects(Projects Larger Than 2 Acres,But Less Than 200 Acres)
Medium Projects in the City of Pearland will have their mitigation detention
volumes calculated using the Small Watershed Method presented in Section
5.6.2. All calculations shall be presented to the office of the City Engineer,
including maps of suitable scale showing the flow paths used to calculate
the existing and developed time of concentration. Hydrograph routing
through the detention basin is recommended. The outflow structures (low
level pipe(s)or opening(s) and high level weir)will be sized as follows:
Page 50 of 65 Storm Sewer Design Criteria
a. Determine the storage elevation in the basin for 3-year, 10-year, and
100-year storm events.
b. Determine water surface elevation in the receiving system(if reasonably
able to) for the 3-year, 10-year, and 100-year storm events.
c. Determine the minimum flowline elevation for the outflow structure.
d. Use the orifice equation to compute the opening size(s)as follows:
Q=CA2gH ,
where: Q=Basin Outflow(cfs),
C=Pipe Coefficient,
A=Restrictor cross-sectional area,
g=Acceleration due to gravity(32.2 ft/s2), and
H = The elevation difference between the detention
basin water surface elevation for the design
storm and the receiving system for a given storm
or the center of the restrictor pipe(feet).
Round up to the next half-foot diameter for restrictor pipes above 18-inch
diameter. Some additional blockage of the pipe may be necessary to obtain
the correct restrictor area(A). No restrictor pipes shall be less than 6 inches
in diameter. The restrictor shall always be placed at the upstream end of a
pipe to enable cleaning.
e. Use weir equation to compute the size of the weir;
Q=CLH3n for rectangular weir equation
Q-Weir discharge in cubic feet per second
C—Weir coefficient
L—Horizontal length of the weir in feet
H—head on the weir in feet
The value of"C" depends on weir shape. Please see appropriate hydraulic
handbook or other applicable references such as HCFCD manual.
For ponds discharging into creeks or ditches, the outfall structure shall be
designed for the 3, 10 and 100-year storm frequencies. Determine the 3, 10
and 100-year detention volumes and compute the water surface elevations
to determine restrictor size to detain to undeveloped flow rates. Use a
vertical structure or multiple pipes separated vertically with the top of the
structure or flowline of the second pipe set at the 3-year or 10-year water
surface so as to be over topped in greater storms. A weir set below the 100-
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year developed water surface elevation shall be used to discharge during the
100-year design condition. This weir should be sized so that the peak
discharge does not exceed the 100-year pre-developed discharge with the
basin full and the tailwater elevation at or below the top of the discharge
pipe.
Storm events in excess of the 100-year event must be considered in the
design of detention facilities from the standpoint of overtopping. For a
detention facility that is an excavated pond and has no dam associated with
it, the outflow structure must be designed with an overflow structure or
swale. This will allow the passage of extreme events with no adverse
impacts to adjacent structures. For detention facilities with a dam, the
possibility of dam failure must be considered as part of the design. Specific
dam criteria for storm events in excess of the 100-year design storm shall
be established by the office of the City Engineer on a case-by-case basis.
Regardless of the results of the methodology selected, the minimum
detention required for all medium projects shall be 0.65 acre feet per
acre of the project area expected to be disturbed for grading in addition
to floodplain fill mitigation.
C. Large Projects (Projects larger than 200 acres)
For projects in excess of 200 acres, HEC-HMS, HEC-RAS modeling shall
be performed. The HEC-HMS modeling shall include analysis of existing
and developed runoff. This analysis must demonstrate no increase in runoff
for the 3-year, 10-year, and 100-year storm events. Similarly a HEC-RAS
model shall demonstrate no increase in the water surface elevation of the
receiving system for the 3-year, 10-year, and 100-year storm events. If the
modelling is associated with a FEMA submittal,the models to be used must
be acceptable to that agency. See 5.6.3 for specific design requirements.
The design of a detention basin basically consists of the following major
phases:
a. Determination of a 3-year, 10-year and 100-year 24-hour design storm
inflow hydrograph to the proposed detention basin.
b. Determination of the maximum 3-year, 10-year and 100-year 24-hour
design storm allowable outflow rate from the detention basin. Outflow
rates shall be equal to or less than historical rates or rates for pre-project
conditions.
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c. Design tailwater elevation will be assumed to be equal to the top of the
outflow pipe or 10-year water surface elevation of the receiving creek
whichever is higher.
d. Preliminary sizing of basin storage capacity and the outflow structure.
e. Routing of the design inflow hydrograph through the basin, and
adjustment of the storage and outflow structure, if required, to ensure
that the maximum allowable outflow rate is not exceeded. This routing
should be performed in an appropriate computer program such as
Interconnected Pond Routing(ICPR) and XP Stormwater Management
Model(XP-SWMM)(or others as approved by the City Engineer). The
outflow structure shall include a pipe or pipes sized to restrict discharge
to the allowable 3-year and 10-year outflow rates and the allowable 100-
year design flow.
f. Analysis of the hydraulic gradients for storm sewers and inflow
channels entering the basin to insure that these systems will operate
properly under design water surface conditions in the basin.
g. Analysis of rainfall events in excess of the design frequency for
structural and flood considerations,including provisions for a high level
overflow structure.This design shall consider the possibility that should
the normal outlet structure from the basin fail, the stormwater can pass
through, over or around the detention basin without damaging adjacent
structures.
h. Investigation of potential geotechnical and structural problems.
Regardless of the results of the methodology selected, the minimum
detention required for all large projects shall be 0.65 acre feet per acre
of the project area expected to be disturbed for grading in addition to
floodplain fill mitigation.
5.8.4 Off-Site Facilities
Off-site detention facilities will generally be regional in nature. The facility may
be sized for one development,but will be designed to serve theentire watershed by
reducing the flood potential of a stream. Most of these facilities are envisioned to
be adjacent to a channel to receive flood water from the main drainage artery
through a system of multistage inlet pipes and high level weirs.
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For the design of an off-site detention basin, the hydraulics of the stream and flood
damage relationship of the watershed must be evaluated. This will be performed
under the direction and advice of the office of the City Engineer. This evaluation
will result in flood frequency/stage-damage estimates of the stream.
Upstream discharge of unmitigated runoff into a stream, on which capacity is
reserved in a regional detention basin, may be allowed if analysis of stormwater
flow demonstrates that flood water surface elevations will not cause flooding
between release point and the detention reservoir.
Sizing of the multistage inlets will be based on a plan that will be most beneficial
to the downstream community. Side flow diversions will also be developed and
evaluated by iterations to evaluate the impact of the diversion on the downstream
hydrographs. The arrangement of pipes/weirs shall be designed to minimize
property damages due to different storms within the entire area served by detention.
The office of City Engineer will advise the design engineer in regards to specific
design configurations.
Off-site facilities will be analyzed using HEC-HMS modeling techniques as
discussed in Section 5.6. The 3-year, 10-year and 100-year will be performed.
Input from the office of the City Engineer is recommended to determine the most
appropriate level to set diversion structures for watershed-wide flood damage
mitigation. These facilities will generally be located along a FEMA studied stream
with adequate models available for the analysis. Routing of the inflow 3-year, 10-
year and 100-year hydrographs through the detention basin may also be performed
using a computer model such as ICPR, XP-SWMM or other detention reservoir
models approved by the office of the City Engineer. Set the tailwater level in the
receiving stream equal to the top of the outfall pipe or 10-year water surface
elevation of the receiving creek,whichever is higher. In addition, the use of a time-
stage tailwater hydrograph for the receiving creek is encouraged for setting the
tailwater requirement.
For off-site facilities,the existing models will be used to develop a proposed(post
project) condition model(s). For such analysis,the proposed.development will not
be isolated as a separate subarea. The existing hydrograph parameters(Tc+R)will
be modified or revised to reflect changes in percent land urbanization (DLU),
percent channel improvement (DCI), percent channel conveyance (DCC), and
percent impervious cover. Watersheds being developed may lose some or most of
the percent ponding(DPP)that may exist in the rural portion of certain watersheds.
Because the project area will not be modeled as a separate subarea,the high inflow
to the main drainage artery will not be evident in the model. Rather, because the
subarea parameters will be revised to reflect the impact of the project, the total
Page 54 of 65 Storm Sewer Design Criteria
hydrograph along the main artery will increase without detention mitigation. The
diversion of the flood waters near the peak of the hydrograph will be effected
through the use of multilevel pipes and a weir to mitigate the increase flow to
downstream reaches.
Regardless of the results of the methodology selected,the minimum detention
required for all projects shall be 0.65 acre feet per acre of the project area
expected to be disturbed for grading in addition to floodplain fill mitigation.
5.8.5 Pump Detention System
All stormwater detention facilities requiring mechanical pumping systems are
generally prohibited, with the exception of pumping of dead storage (maintenance
or amenity water stored at or below the discharge pipe control level). However,
pumped detention shall be allowed under the following conditions:
A. A combination pump and gravity system shall be constructed.
B. The minimum detention rate shall be 0.70 ac-ft/ac.
C. No more than 75%of the total pond capacity shall be pumped.
D. The detention pond shall be designed to empty the storage volume within
72 hours.
E. The discharge delivery system shall not have peak discharge and/or peak
stages that exceed the pre-developed peak values at any point in time for the
3-year, 10-year and 100-year design storm events.
F. Two pumps minimum shall be required, each capable of providing the
design discharge rate. If three pumps are used, any two pumps must be
capable of handling the design discharge rate. The total discharge pumping
rate shall not exceed the design discharge rate.A gravity overflow route and
outfall must be submitted to the office of the City Engineer for approval.
Pumping from detention into an existing storm sewer is prohibited unless
the pre-developed land already drains into an inlet and storm sewer system.
G. Pumped detention shall not be allowed for detention basins that collect
public water runoff, except for detention basins owned, operated and
maintained by the City or Brazoria Drainage District #4. Public water
runoff shall be defined as runoff water that originates from the property of
more than one property owner.
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H. Fencing of the control panel is provided to prevent unauthorized operation
and vandalism, pursuant to the Texas Commission on Environmental
Quality Standards.
I. Adequate assurance is provided that the system will be operated and
maintained on a continuous basis.
J. Emergency source of power is provided for those cases that loss of power
during a 100-year flood event would cause property damage.
K. Sensors must be placed so that pumps would remain off during a rain event.
Additionally, sensors must be placed so that pumping will not occur when
the level of water in the receiving system is at or above 1/4 of its full depth.
L. The Operator shall provide the office of the City Engineer with a quarterly
operational report that shall indicate the operational times, total hours of
operation, and the amount pumped. This report shall be delivered to the
office of City Engineer at the end of each quarter, no later than the 15th of
the month.
M. The City shall have the right to enter the property and inspect the operation
of the system at any time for any reason.
N. Failure to maintain the pump station in working order is a violation of these
requirements and the City Ordinance for Maintenance of Stormwater
Storage Facilities.
It is recommended that if a pump system is desired, approval by the City of
Pearland of the preliminary conceptual design be obtained before any detailed
engineering is performed.
5.8.6 Structural and Geometric Parameters for Detention Ponds
A. General
Two types of detention facilities are acceptable in the City of Pearland. The
first is a naturalized basin in which standing shallow pools of water and
muddy areas are allowed to exist along the bottom of the basin and support
natural or wetlands vegetation. This type of basin is only maintained around
the sides and perimeter and involves special design considerations at the
outfall structure. Designing this type of facility must be approved by the
City and must consider the aesthetics of the surrounding area.
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The second type of detention facility is a manicured or well-maintained
basin,which is mowed regularly and is designed to stay dry between rainfall
events. This type of facility may be more aesthetically pleasing in heavily
populated areas and is more amenable to multiple uses such as parks or ball
fields. The design considerations for each facility are outlined below.
The following parameters shall apply to all detention facilities:
a. Side slopes shall be 4:1 or greater.
b. Minimum maintenance berms shall be as follows:
Pond Depth Width of Berm
0'-2' 10'
>2'-5' 15'
>5'-10' 20'
>20' 30'
c. When a detention facility is constructed adjacent to a BDD4 channel,
BDD4 requirements prevail.
d. Maintenance berms shall not be encumbered by any other permanent
improvements, easements, fee strips, or right-of-way.
B. Wet Detention Pond(Static Water Level)
Wet detention pond must be approved by the City prior to the design and
preparation of construction plans. The design requirements such as
maintenance berms,backslope drains, and erosion protection measures are
required for all detention ponds. A maintenance plan to remove trash debris
and excessive siltation must be provided to and approved by the City. The
depth of permanent pool shall not be less than 4 feet. Additional storage
volume may be required by the City to offset predicted siltation based on
experiences with nearby storage facilities. It will be responsibility of the
developer, MUD, Homeowner Association, or Landowner to own and
maintain any wet detention ponds.
C. Bottom Design for Naturalized Detention Facilities
The bottom of a detention facility, which is intentionally meant to support
natural vegetation, should be designed as flat as practical but still maintain
positive drainage to the outfall structure. Side slopes should be designed to
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allow for regular maintenance and be grass-lined with a 4:1 slope. The
bottom should be graded toward the outfall structure at a minimum slope of
0.002 feet per foot. The remainder of the pond bottom shall be graded
toward the flowline of the pond at a minimum of 0.01 feet per foot. Selected
vegetation may be introduced to the bottom of the facility to encourage a
particular habitat. Other design requirements for channels should be
followed, including back slope drains and erosion protection measures. A
maintenance plan to remove trash debris and excessive siltation must be
provided to and approved by the City. Additional storage volume may be
required by the City to offset predicted siltation based on experiences with
nearby storage facilities.
D. Bottom Design for Manicured Detention Ponds
The design of the detention basin bottom to remain dry and aesthetically
manicured is very important from the standpoint of long term maintenance.
A pilot channel is required to facilitate complete drainage of the basin
following a runoff event. A lined concrete pilot channel should have a
minimum depth of 6 inches and a minimum flowline slope of 0.002 feet per
foot. An unlined pilot channel should have a minimum depth of two feet, a
minimum flowline slope of 0.005 feet per foot, and maximum side slopes
of 4:1.
Bottom slopes of the detention basins should be graded towards the low-
flow pilot channel or outfall. The transverse slope of the bottom should be
a minimum slope of 1%,with 2%preferred.
Detention basins which make use of a channel section for detention storage
may not be required to have pilot channels but should be built in accordance
with the requirements for channels, including side slopes, maintenance
berms, back slope drains and erosion protection measures previously
discussed.
E. Outlet Structure
For low tail water conditions, the outlet structure for a detention basin is
subject to higher than normal headwater conditions and possibly erosive
velocities for prolonged periods of time. For this reason, the erosion
protective measures are very important.
Reinforced concrete pipe used in the outlet structure should conform to
ASTM C-76 Class III with compression type rubber gasket joints
conforming to ASTM C-443. HDPE or aluminized steel pipes may also be
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used. Pipes, culverts and conduits used in the outlet structures should be
carefully constructed with sufficient compaction of the backfill material
around the pipe structure as recommended in the geotechnical analysis.
Generally, compaction density should be the same as the rest of the
structure. The use of pressure grouting around the outlet conduit should be
considered where soil types or conditions may prevent satisfactory backfill
compaction. Pressure grouting should also be used where headwater depths
could cause backfill to wash out around the pipe. The use of seepage cutoff
collars is not recommended since such collars are often inadequately
installed and prevent satisfactory backfill compaction. A concrete control
structure with a grate area equal to ten(10)times the outfall pipe area shall
be constructed. Concrete paving extending from the outfall area into the
basin a distance of 10 feet shall be placed on the bottom of the basin for
maintenance of the structure. Adequate steel grating around the outfall pipe
intake must be designed to prevent clogging of the pipe from dead or
displaced vegetation.
The concrete or articulated block on filter fabric spillway for the 100-year
discharge or greater flows shall extend down the bank to the bottom of the
channel and up the far side.
F. Extreme Event Spillways
The drainage system must be designed to adequately deal with an extreme
rainfall event. The extreme event shall be defined as an event which
includes or exceeds the 100-year flow. A sheet flow analysis shall be
provided to show this extreme event flow path to the receiving drainage
system.
A concrete lined extreme event overflow swale shall be provided where this
event enters and exits the detention pond. The BDD4 or County's standard
details shall be used for drainage system outfall into the BDD4 or County's
receiving channel.
G. Additional Design Considerations
The following items describe additional design criteria associated with
detention basins.
a. Erosion Control
Adequate erosion control and re-vegetation shall be accomplished
during and following construction of the basin. The City of Pearland
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will allow articulated block on filter fabric as an acceptable means of
slope protection.
b. Safety,Aesthetic Consideration and Multi-Purpose Use
The use of a detention basin facility generally requires the commitment
of a substantial land area for the basin. The City of Pearland recognizes
that such a facility may be used for other purposes which are compatible
with the primary intended purpose of providing flood control. Basins
may be utilized as parks and recreational facilities on a case-by-case
basis. Also, a parking area may be used for a portion of the storage as
long as the 100-year water depth is no greater than 9 inches where cars
are parked. The proposed use and the facilities to be constructed within
the basin area must be specifically approved by the City of Pearland.
The City of Pearland will not assume any maintenance responsibility on
or within private detention facilities.
5.9 MISCELLANEOUS DESIGN CONSIDERATIONS
5.9.1 Storm Sewer Outfalls
All storm sewer outfall structures should be constructed in accordance with the City
standard details, Brazoria Drainage District No. 4 details, or Harris County Flood
Control District's details depending upon the outfall location. Design criteria for
outfall structures is as follows:
A. All storm sewer outfall pipes within the City of Pearland right-of-way must
be reinforced concrete pipe with rubber gasket joints,aluminized steel pipe,
or HDPE with a minimum diameter of 18 inches.
B. All backslope drains shall be 24-inch reinforced concrete pipe, aluminized
steel or HDPE.
C. A standard City of Pearland manhole or junction box must be outside of the
City of Pearland ultimate right-of-way. Where a road or railroad right-of-
way is located adjacent to the channel, the manhole may be placed within
the City of Pearland right-of-way.
D. The grade of the pipe should be that required to produce a three feet per
second velocity when flowing full.
E. Erosion protection is required for all outfall pipes.
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F. Effluent outfalls from treatment plants shall have a paved invert and riprap.
5.9.2 Special Erosion and Velocity Control Structures
A. General
Special erosion and velocity control structures will generally include stilling
basins, baffled aprons, straight drop spillways, sloped drops, and impact
basins. Due to the hydraulic and earth loads encountered through these
structures,the structural as well as the hydraulic design is very critical.
A geotechnical engineering investigation to determine the characteristics of
the supporting soil is required for major hydraulic structures
B. Straight Drop Spillway
Straight drop spillways are usually constructed of steel sheet piling with
concrete aprons. Steel sheet pile drop structures can sometimes be
considered a temporary structure.
The distance erosion protection aprons extend upstream and downstream of
the drop is determined using hydraulic analysis. The City of Pearland
recommends using concrete paving upstream and immediately downstream
of the drop. Because of the additional impact load on the downstream slope
paving, a 6-inch thick pad is recommended. Articulated blocks placed on
geotextile fabric should be used at the ends of the concrete paving to
decrease flow velocities and protect the concrete toe.
The drop structure should be designed for active and passive soil forces.
Design calculations are required for each drop structure along with a copy
of a geotechnical report defining soil characteristics of the site.
C. Baffle Chutes
See Reference 3.23 for hydraulic and structural criteria regarding baffle
block chutes.
D. Sloped Drop Structures
Sloped drop structures can be made of either monolithic poured-in-place
reinforced concrete or articulated cellular concrete block mats. The same
design principles hold true for sloped drop structures as for straight drop
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structures; i.e.,the draw down curve and hydraulic jump must be contained
within the structures or stilling basin.
The sloped drop structure should have 24-inch toe walls on the upstream
and downstream ends. The sides of the structure should have 18-inch toe
walls.
If an articulated cellular concrete block drop structure is used, the blocks
should be bedded on a filter fabric. The fabric should be heavy duty and
designed for the specific soil condition. The size and weight of the blocks
should be designed for shear forces.
E. Utility Crossings
Approval must be obtained from the office of the respective authorities(the
City,BDD4,or Counties)for all utility lines which cross a drainage facility.
The utility crossing should be designed to minimize obstruction of the
channel flow and conform with the ultimate channel cross-section. Contact
the offices of the respective authorities for information regarding the
ultimate channel section and ultimate channel right-of-way at a proposed
crossing prior to design.
All utility lines under channels should be constructed with the top portion
of the conduit a minimum of five (5) feet below the projected flow line of
the ultimate channel... When appropriate, facilities may be constructed on
special utility bridges or trestles in accordance with standard bridge design
criteria. Pipes or conduits spanning the channel should be located 2' above
the base flood elevation for hydraulic and maintenance reasons. For utility
crossings on street bridges, contact the appropriate government body for
approval.
All manholes required for the utility conduit shall be located outside the
City of Pearland ultimate right-of-way. Backfill within the City of Pearland
right-of-way shall be in accordance with the backfill requirements specified
by the respective city, county, or utility company.
5.9.3 Stormwater Management
Stormwater Management shall always be an integral part of the drainage
improvement. See chapter 8.0 Stormwater Management for details.
5.10 REPORT REQUIREMENTS
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Drainage Report/Drainage Impact Analysis must be approved prior to submittal
and approval of the Construction Plan. The drainage report must include minimum
of the following items listed in the drainage report.
EXECUTIVE SUMARY
Include detention summary table for the projects with detention.
SECTION 1: INTRODUCTION
• Project Name and Purpose
• Project Limits
• Project Objectives
• Assumptions and Constraints
• Prior Studies if any
Exhibits
o Vicinity Map/Aerial Map
SECTION 2: EXISTING CONDITIONS
• Location and Topography
• Land Use
• FEMA Floodplains
• Right-of-Way
• Pipelines and Utilities
• Survey Datum
Exhibits
o Typical Roadway Section(Existing and Proposed) for roadway projects
SECTION 3: HYDROLOGY AND HYDRAULICS
• Design Criteria-guidelines used, storm frequency,mitigation requirements etc.
• List of programs and software used: include the purpose of uses
• Hydrologic Methodology
• Hydraulic Methodology
• Pre-Project Conditions
Exhibits
o Overall Drainage Area Map
o Existing Drainage Area Map with 3, 10, 100 year flows and water surface
elevations at Major Outfall Nodes
o Floodplain Maps with project boundary shown on it
SECTION 4: PROPOSED DRAINAGE PLAN
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• Description
• Hydrological Analysis—Rational Method, Small Hydrograph Method, HEC-
HMS, etc.
• Hydraulic Analysis—Stormsewer design, Spreadsheet, Winstorm,ICPR,
XPSWMM,HEC RAS,Applicable Sheet Flow Analysis, etc.
• Channel and/or detention layout
• ROW requirement
• Pipeline and Utility Conflicts
• Geotechnical Requirement
• Environmental Issues
Exhibits
o Overall Drainage Area Map
o Proposed Drainage Area Map with 3, 10, 100 year flows and water surface
elevations at Major Outfall Nodes
o Floodplain Maps with project boundary shown on it
o Detention Pond layout with detention summary
o Plan and Profile with 10-yr and 100-yr WSE in case of Roadway
SECTION 5: CONCLUSION
When a detention facility is part of the proposed project, include the following detention
summary table:
Project Name
Detention Basin Area Acres
Detention Storage Rate Acres-Feet/Acre
Detention Storage Required Acre-Feet
Detention Storage Provided Acre-Feet
Floodplain Fill Mitigation Acre-Feet
Volume
Storm Event --% (---Yr) 10% (10-Year) 1% (100-Year)
Design Water Surface
Elevation( Datum,
Adjustment)
Maximum Allowable
Outflow 9cfs)
•
Maximum Outflow Provided
(cfs)
APPENDIX
• Detailed Hydrological Calculations
• Detailed Hydraulic Calculations
Page 64 of 65 Storm Sewer Design Criteria
5.11 QUALITY ASSURANCE
Prepare calculations and construction drawings under the supervision of a Professional
Engineer(Civil/Structural/Environmental) licensed in the State of Texas. The final
construction drawings and all design calculations must be sealed, signed, and dated by
the Professional Engineer responsible for the development of the drawing.
•
Page 65 of 65 Storm Sewer Design Criteria
•
•
•
J
CaI a ti Fo : r Storm ewe•
•
•
•
4. .
FIGURE 5.5-1:STORM SEWER CALCULATION TABLE
CITY OF PEARLAND
STORM FREQUENCY:XX-YR
Project:
By:
Date:
Node Rainfall Une Flow Une Design Actual HGL TOC/RIM NGL-TOC
Area Total Area HGL
C Factor Time of Intenstity Flow Q Reach Mann Flow Q Velocity
From To (AC) (AC) Conc.(TC) (IN/HR) (CFS) (FT) Size(IN) Const(n) U/S(Fr) D/S(FT) V(FPS) (CFS) (FPS) Slope(%) U/S(Fr) D/S(FT) U/S(Fr) D/S)(Fr) U/S(Fr) D/S(FT)
CITY OF PEARLAND
CHAPTER 6
ROADWAY DESIGN CRITERIA
ENGINEERING DESIGN CRITERIA MANUAL
December 2018
Page 1 of 33 Roadway Design
Criteria
CHAPTER 6
ROADWAY DESIGN CRITERIA
6.1 GENERAL
6.1.1 All construction plans containing proposed roadways, sidewalks, and
driveways in a public right-of-way shall be reviewed by the City Engineer
for all improvements within the city limits.
6.1.2 All new streets installed within the city limits shall be concrete curb and
gutter. New street construction that utilizes roadside ditches for storm
water drainage is discouraged and must receive specific approval of the
City.
6.1.3 Street design shall conform to all applicable planning tools such as the City
of Pearland Unified Development Code requirements, latest edition of the
Texas Manual on Uniform Traffic Control Devices, Pearland
Comprehensive Plan, Pearland Major Thoroughfare Plan, and Master
Parks Plan and Master Trails Plan. Other consideration for design shall
include roadway function, capacity, levels of service, traffic safety, the
AASHTO Policy on Geometric Design of Highways and Streets,
Americans with Disabilities Act (ADA) regulations on accessibility
design, pedestrian safety, and all utility locations including gas, cable and
power lines. Any deviation using other materials or other design criteria
requires prior approval by the City.
6.1.4 Design shall conform to the City of Pearland construction details where
applicable. These criteria shall not apply to proposed streets projects
located in Texas Department of Transportation(TxDOT),Brazoria County
or Harris County owned and/or maintained right-of-way.
6.1.5 On a case-by-case basis the City of Pearland reserves the right to allow
deviations from these design criteria.These design criteria are not intended
to cover repairs to-existing streets or street extensions when such repair
work or extensions are performed by City of Pearland in whole or in part.
These criteria are not intended to cover existing streets within the City of
Pearland that do not already conform to these criteria.
6.1.6 These are to be considered minimum guidelines but the City of Pearland
may require a Traffic Impact Analysis at no cost to the City where the City
of Pearland deems it is warranted.
6.2 GENERAL ROADWAY DESIGN GUIDELINES
6.2.1 Public Roadways - The standard for public roadways within the City of
Page 2 of 33 Roadway Design
Criteria
Pearland city limits and extra-territorial jurisdiction are concrete,curb-and-
gutter construction, served by underground storm sewers.
6.2.2 Roadway Classifications - The City of Pearland recognizes three basic
classifications of public roadways that include major and secondary
thoroughfares, major and minor collectors, and local streets. Each class
provides a certain degree of continuity, capacity, and accessibility to
adjacent land uses. While differentiated by function,there is also a variance
in geometric design. The typical cross-sections are depicted in Figures 6.3.1
and 6.3.2.
6.2.3 Roadway Geometrics - Geometrics of city streets may be defined as the
geometry of the pavement and curb areas that govern the movement of
traffic within the confines of the rights-of-way (ROW). Included in the
geometrics are pavement width, degree of curvature, width of traffic lanes,
median nose radii,curb radii at street intersections,cross fall,crown height,
pavement thickness and geometric shapes of islands separating traffic
movements and other features.
6.2.4 Design Speed- The design speed is a primary factor in the horizontal and
vertical alignment of roadways. Design features such as curvature, super-
elevation, turning movement radii and sight distance affects roadway lane
width, pavement width, pavement cross-slope, pavement crown and
clearances.
6.2.5 Grades - Roadway grades shall be a minimum of three-tenths percent
(0.3%) in order to insure proper flow of surface drainage toward inlets and
a maximum of six percent(6%). Steeper grades may be permitted on local
residential streets and where required by topographical features, as
approved by the City Engineer.
6.2.6 Roadway Centerline-Roadways shall be placed in the center of the ROW,
but may be shifted slightly, with prior City approval,to avoid groupings of
trees. The centerline of curves shall be tangent to the centerline of street at
each end of curve.
6.2.7 Cross Slope/Crown Height— Thoroughfares shall have a minimum cross
slope of one-quarter inch per foot and a maximum cross slope of three-
eighths inch per foot. Major and minor collectors and local streets shall
have six-inch (6") crowns.
6.2.8 Pavement Strength & Thickness - All concrete pavement and curbs shall
be a minimum 3,500-psi and shall meet the structural requirements of this
manual.
6.2.9 Sight Distance - All intersections on major thoroughfares and major
collectors and intersections of other streets with adjacent community
Page 3 of 33 Roadway Design
Criteria
fencing, monument signs or hardscaping, horizontal curves and vertical
curves shall be evaluated for adequate sight distances in accordance with
AASHTO guidelines. Sight distance triangles shall be shown on the plan
view of construction plans.
6.2.10 Channelization-Channelization shall conform to American Association of
State Highway and Transportation Officials"A Policy on Geometric Design
of Highways and Streets", latest edition.
6.2.11 Private Streets—Private streets are streets that are not owned by the City of
Pearland,the State of Texas or the County and are not dedicated for public
use. All private streets shall be constructed to the same standards as public
streets.
6.2.12 Requirements for Thoroughfares within master planned developments and
planned unit developments
1. The full right-of-way for major and secondary thoroughfares
adjacent to developments shall be dedicated at the time of platting
of the development.
2. When the full section of a thoroughfare is located within the city
limits and is dedicated on a fmal plat,the esplanade and all lanes of
the thoroughfare shall be constructed at the time of development of
the adjacent subdivision.
3. If approved by the City Engineer, one-half of the thoroughfare,
including travel lanes, left-turn lanes and the esplanade to the
centerline of the right-of-way shall be constructed at the time of
initial construction of the adjacent development. The remainder of
the thoroughfare shall be constructed at the time the property
adjacent to the unconstructed half is developed.
4. Permanent barricades, conforming to the requirements of the Texas
Manual of Uniform Traffic Control Devices, shall be constructed at
the termination of lanes on partially constructed thoroughfares. The
barricades shall include a sign reading FUTURE ROADWAY
EXTENSION mounted on a breakaway pole and located one foot
behind the barricade,with the bottom of the sign one foot above the
top of the barricade.
6.2.13 Standard City barricades shall be placed at the end of dead-end streets not
terminating in a cul-de-sac.
6.2.14 At a T-intersection with a street that has not been improved to its ultimate
width, the concrete pavement of the intersecting street shall be stopped
Page 4 of 33 Roadway Design
Criteria
either at the right-of-way line or the end of the curb return,whichever would
require less concrete removal at a future date.
6.2.15 For roadway turnouts placed at an existing cross street intersection, the
turnout should be designed to fit the ultimate pavement width of the
intersecting cross street and then transitioned to the existing roadway.
6.2.16 Residential driveways shall not access major thoroughfares or collector
streets without written approval from the City Engineer. Subdivision
layouts shall be designed to avoid homes requiring collector street access.
6.3 ROADWAY CLASSIFICATIONS
6.3.1 Major Thoroughfare, 4 or 6 lanes, divided roadway: Shall provide a high
degree of mobility, serve relatively high traffic volumes, have limited
access, have high operational speeds and serve a significant portion of
through travel and traffic movement by serving as the major traffic
corridors. Usually constructed within a minimum 120 ft. wide right-of-
way.
6.3.2 Secondary Thoroughfare, 4 lanes, divided or undivided roadway: Serve
same function as principal arterials but typically have a lower traffic
volume. Usually constructed within a minimum 100 ft.wide right-of-way.
6.3.3 Major Collector, 4 lanes, undivided roadway: Shall be used in multi-
family, commercial or industrial areas as well as secondary streets.
Usually constructed within a minimum 80 ft. wide right-of-way.
6.3.4 Minor Collector,2 or 3 lanes,undivided roadway: Shall be used for minor
collector streets in single family residential areas or local multi-family
residential, commercial, or industrial areas as well as secondary streets
where defined. May have two travel lanes and a center continuous left-
turn lane, or 2 lanes with on-street parking. Usually constructed within a
minimum 60 ft. wide right-of-way.
6.3.5 Local, residential, 2 lane, undivided roadway: Include internal and access
streets that allow direct access to residential properties and similar traffic
destinations and typically have low design speeds and low traffic volumes.
Usually constructed within a minimum 50 ft. wide right-of-way.
Page 5 of 33 Roadway Design
Criteria
MAJOR THOROUGHFARE
(6-Lane Divided C&G Roadway)
l• 4.-\
II •
a a + * *
2'- 6' 6' 12' 12' 12'. 18' 12' 1212 2
c' LANE LANE LANE MEDIAN LANE LANE LANE < c
om -9 -c -c
P- T, a
r- b r r
X z
37'ROADWAY 37'ROADWAY
120' ROW
MAJOR THOROUGHFARE
(4-Lane Divided C&G Roadway)
- 1111.11 , M . " it ;fa._ ..- iiiiiithige
II i •
2 6' 6' 12' 12' 42'—_ 12'---- 12' 6' --6'—2'_
{ LANE LANE MEDIAN LANE LANE < g
2 mm v v m 32
C)n * n A • y�y
D r P'
x
24'ROADWAY 37'ROADWAY
120' ROW
SECONDARY THOROUGHFARE
(4-1 ane Divided C&G Roadway)
/--qk
a a * t
2'- 6' 8' 12'--1----12'--, 18' 12' 12• _g' 6' 2
o v I
m
LANE 1 LANE MEDIAN LANE LANE TYPICAL fa
'�T 2
P g r r r
7c
3T ROADWAY —.37'ROADWAY
100' ROW
Figure 6.3.1 —Cross Sections for Thoroughfare
(All dimensions are face-to-face)
Page 6 of 33 Roadway Design
Criteria
MAJOR COLLECTOR
(4-Lane Undivided C&G Roadway)
a a t
2'---6' 7.5' --.-12' 12 12 12'—; 7.5' • 6' 2
TYPICAL LANE LANE LANE LANE ' TYPICAL o
� n
80' ROW - -
MINOR COLLECTOR
(2-or 3-Lane Undivided C&G Roadway)
•= i1
s — —
2' • 5' 4.5'— :-12' 12' 12'. j- 4.5' • 5' 2'
v TYPICAL LANE CENTER LANE TYPICAL m
•
In
J �
37'ROADWAY
60' ROW
LOCAL ROADWAY
(2-Lane C&G Roadway)
i
2' 5' 4' 28' IY_tT
4 o TYPICAL ROADWAY ; TYPICAL
-v
50' ROW
Figure 6.3.2—Cross Sections for Collector and Local Roads
(All dimensions are face-to-face)
Page 7 of 33 Roadway Design
Criteria
6.4 GEOMETRIC STREET DESIGN STANDARDS
6.4.1 Minimum geometric street design standards for number of lanes, lane
widths,right-of-way widths, and median widths shall be as follows:
Table 6.4.1
Major Major Secondary Major Minor Local
Thoroughfare Thoroughfare Thoroughfare Collector Collector Street
Right-of-Way Width 120 feet 120 feet 100 feet 80 feet 60 feet 50 feet
Curb Back to Curb Back Distance N/A N/A N/A _ 45 feet 37 feet 28 feet
Median Width(bc-bc)(2) 18 feet 42 feet 18 feet N/A N/A N/A
Distance from Curb Back to ROW line 14 feet 14 feet _ 16 feet _ 17.5 feet 11.5 feet 16 feet
Distance from ROW Line to Sidewalk Varies _ Varies Varies Varies _ Varies Varies
Max.Number of Lanes(one direction) 3 2 2 2 1 1
(1) With on-street parallel parking.
(2) Median turning lanes are included in median widths.
6.4.2 The design speeds shall conform to the following design standards. The
posted speed limit shall never exceed the design speed. The design speed
should be a minimum of 5 mph greater than the posted speed limit.
Table 6.4.2
Urban
Thoroughfares 40-60 mph
Collectors 30-50 mph
Local 30 mph
6.4.3 The maximum grade allowed refers to the uphill or downhill slope of the
street and shall conform to the following design standards:
Table 6.4.3
Thoroughfares
Design Speeds(mph)
30 35 40 45 50 55 60
Type of Terrain Maximum Grades(%)
Level 8 7 7 6 6 5 5
Table 6.4.4
Collectors
Design Speeds(mph)
20 25 30 35 40 45 50 55 I 60
Type of Terrain Maximum Grades(%)(I)
Level 9 9 9 9 9 8 7 7 I 6
(1) Short lengths of grade in urban areas, such as grades less than 500 ft in length,
one-way downgrades, and grades on low-volume urban collectors may be up to
2%steeper than the grades shown above.Note: Sidewalks along these roadways
shall not exceed ADA maximum grade requirements.
Page 8 of 33 Roadway Design
Criteria
6.4.4 Local Roads
A. Grades for local residential streets should be as level as practical,
consistent with the surrounding terrain. The gradient for local urban
streets should be less than 9%. Where grades of 4% or steeper are
necessary, the drainage design shall be the critical governing design
parameter. On such grades special care should be taken to prevent
erosion on slopes of roadside ditches and earthen/grass lined open
drainage facilities. For streets in commercial and industrial areas,
grades should be less than 5%and flatter grades are encouraged.
6.4.5 Vertical curves
A. Vertical curves shall be designed when algebraic difference in grade
exceeds 1%. Elevations shall be shown on the construction plans at a
minimum of ten foot(10') horizontal intervals through vertical curves.
The gradient for tangents to vertical curves at railroad crossings shall be
a maximum of three and one-half percent (3.5%). All crest vertical
curves shall be determined by sight distance requirements for the design
speed. The minimum design speed on any vertical curve shall be based
on roadway classification.
B. Vertical curves are utilized in roadway design to affect gradual change
between tangent grades and will result in design that is safe,comfortable
in operation,pleasing in appearance and adequate for drainage. Vertical
curve alignment shall also provide Stopping Sight Distance(SSD)in all
cases. SSD is a function of design speed, perception-reaction time,
grade, and dynamic friction. The perception-reaction time is assumed
to be 2.5 seconds as stated by American Association of Highway and
Transportation Officials (AASHTO). The dynamic friction is the force
that resists movement of the vehicle while the tires are in a locked
position. The equation for SSD appears below:
SSD= 1.47PV+ ( V2 )
30(f+ g)
Where:
SSD = Stopping Sight Distance (ft); P = perception Reaction Time (2.5
sec.); V=vehicle design speed (MPH); f= coefficient of friction between
tires and roadway; g=percent grade divided by 100
C. To determine the minimum acceptable length of Crest and Sag curves
shown in Tables 6.4.5 and 6.4.6, it is assumed that g=0 in the SSD
calculation. Tables 6.4.5 and 6.4.6 also show values of K. K is defined
as the rate of vertical curvature and is equivalent to the horizontal
distance in feet required to make a one percent (1%) change in grade.
The values of A are equivalent to the algebraic difference in grade
Page 9 of 33 Roadway Design
Criteria
between the two grades that are being joined together by the vertical
curve.
TABLE 6.4.5: Minimum Acceptable Crest Curve Given Speed and Difference in
Grade of Road
Design Length of Vertical Curve (L=KA)
Speed, SSD K
V l�. —
MPH) A=1.2(1) A=2 A=3 A=4 A=5 A=6 A=7 A=8 A=9 A=10
25 155 12 -- 24 36 48 60 72 84 96 108 120
30 200 19 -- 38 57 76 95 114 133 152 171 190
35 250 29 -- 58 87 116 145 174 203 232 261 290
40 305 44 50 88 132 176 220 264 308 352 396 440
45 360 61 50 122 183 244 305 366 427 488 549 610
50 425 84 50 168 252 336 420 504 588 672 756 840
(1)Speeds less than forty miles per hour(40MPH),no vertical curve is necessary. Speeds
greater than forty miles per hour(40MPH),use length of fifty feet(50').
(2)If the algebraic difference (A) is between 1.2 and 2 the length of vertical curve shall be
calculated.
TABLE 6.4.6: Minimum Acceptable Sag Curve Given Speed and Difference in
Grade of Road
Design Length of Vertical Curve (L=KA1
Speedy SSD K
- V Ll —
(MPH) A=1.2(1) A=2 A=3 A=4 A=5 A=6 A=7 A=8 A=9 A=10
25 155 26 -- 52 78 104 130 156 182 208 234 260
30 200 37 -- 74 111 148 185 222 259 296 333 370
35 250 50 -- 98 147 186 245 294 343 392 441 490
40 305 64 50 128 192 256 320 384 448 512 576 640
45 360 79 50 158 237 316 395 474 553 632 711 790
50 425 96 50 192 288 364 480 576 672 768 864 960
(1)Speeds less than forty miles per hour (40MPH), no vertical curve is necessary. Speeds
greater than forty miles per hour(40MPH),use length of fifty feet(50').
(2)If the algebraic difference (A) is between 1.2 and 2 the length of sag curve shall be
calculated
6.4.6 Intersections and curves shall be evaluated for adequate sight stopping
distances based on the design speed.
A. Minimum stopping sight distances shall conform to the following
design standards:
Page 10 of 33 Roadway Design
Criteria
a. The driver's eye height shall be assumed to be 3.5 feet above
the finished pavement.
b. The height of the object seen by the driver shall be assumed
to be 2.0 feet.
c. A deceleration rate of 11.2 feet/s2 shall be used.
d. A brake reaction time of 2.5 seconds shall be used.
e. Minimum sight stopping distances shall be adjusted by the
Professional Engineer of Record,when there is a presence of
vertical curves within the distance needed for stopping as
recommended by AASHTO's A Policy on Geometric Design
of Highways and Streets where applicable.
B. Open space clips shall be established at all intersections. Unless
larger clips are required at a particular intersection, a minimum 10-
foot x 10-foot triangular open space corner clip for zoned residential
areas, as measured from the projected property line, is required at
the intersection of two streets. At intersection of collector streets or
greater,minimum 25-foot x 25-foot open space corner clip or larger,
as design requires, shall be provided. Such clips shall be part of the
public right-of-way and may not be located on private property.
C. Major and secondary thoroughfares with a centerline radius of the right-
of-way less than 2000 feet shall be designed in accordance with the
guidelines for superelevation as specified in the AASHTO A Policy on
Geometric Design of Highways and Streets. Signage and design speed
shall be accounted for in all curved thoroughfares. The maximum rate
of superelevation shall be 0.06 for urban conditions. Streets with a
centerline radius of over 2000 feet are not required to have
superelevation.
D. Collector and local streets horizontal curves may be designed without
superelevation.
E. Minimum Horizontal Curve Radii Lengths:
a. Major Thoroughfares: 2000 feet.
b. Secondary Thoroughfares: 2000 feet.
c. Major Collector Streets: 850 feet
d. Minor Collector Streets: 850 feet.
e. Local Residential Streets: 450 feet.
For radii less than above,designer must receive specific approval from the
City Engineer.
Page 11 of 33 Roadway Design
Criteria
6.4.7 For the purposes of these design standards,tangent length is defined as the
distance between the point of tangency and the point of curvature of two
adjacent curves along the centerline of the street right-of-way.
A. The minimum tangent length between reverse curves shall be 100 feet
on principal arterials,minor arterials,major collector streets, and minor
collector streets.
B. The minimum tangent length between reverse curves shall be 50 feet on
all local streets.
6.4.8 Intersections
A. Curb radii, measured from the face of curb, shall be 35 feet minimum
on major and secondary thoroughfares. The minimum curb radius shall
be 25 feet on collector and local streets. Skewed intersections shall be
designed with larger radius.
B. Streets and traffic lanes should be aligned across an intersection. Except
where existing conditions will not permit, all streets should intersect at
a 90 degree angle. The maximum allowable skew across an intersection
shall be 5 degrees for arterial streets,and 10 degrees on all collector and
local streets.
C. When turnouts are provided at an existing street, the ultimate cross
section is required to the end of the curb return. Pavement transition is
required to reduce the pavement width to the existing cross section.
D. Taper rates for adding or dropping a lane shall be at a minimum of
straight line tapers with a minimum of an 8:1 rate for design speeds up
to 30 mph and 15:1 for design speeds up to 50 mph. For design speeds
over 50 mph the Professional Engineer of Record shall submit a design
providing adequate taper lengths appropriate for the corresponding
design speed. The use of partial tangent tapers, symmetrical reverse
curves, and asymmetrical reverse curves are encouraged and should be
designed to fit the design speed of the design road but are not required.
E. Right-of-Way corner clips are required for all Thoroughfare roadways.
Triangular corner clips shall be a minimum of 25-foot x 25-foot.
F. Collector and local roadways shall have a 25 ft. radius for the right-of-
way at all intersections.
6.4.9 Minimum lane transition lengths shall meet or exceed requirements of the
A Policy on Geometric Design of Highways and Streets. Pavement width
transitions shall conform to the following design standards:
Page 12 of 33 Roadway Design
Criteria
A. Minimum deceleration lengths for auxiliary turning lanes on grades of
less than or equal to 3%, with an accompanying stop condition, for
design speeds of 30,40,45, 50, 55 mph are 230, 330,430, 550 and 680
feet respectively. These lengths exclude the taper lengths.
B. Taper lengths should be calculated for roads with design speeds greater
than or equal to 45 mph by using taper lengths(L)equal to 0.6 times the
design speed (S) multiplied by the offset (W), L=0.6SW. For design
speeds less than 45 mph,the taper length(L)equals the offset multiplied
by the design speed(s) squared, then divided by 155, L=WS2/155. The
distance for tapers should be lengthened if the road is curved based on
recommendations from the Professional Engineer of Record.
6.4.10 Left Turn Lanes
A. Minimum storage bay length shall be 100' for collector streets and 150'
for thoroughfare streets. Longer storage bay lengths may be required
based on the results of a Traffic Impact Analysis.
B. Mid-block left turn lanes may be allowed if a Traffic Impact Analysis
and the City Engineer recommends their use in relation to a proposed
development. Left turn lanes shall be provided at the intersection of
public street rights-of-way.
C. Minimum transition taper length with 500' Radius shall be 180' for
Collector streets and 200' for thoroughfares.
D. The City Engineer reserves the right to require that a Traffic Impact
Analysis be submitted for any proposed development.
E. Left-turn lane width shall be a minimum of 12 ft.
6.4.11 On major and secondary thoroughfares esplanade openings may be spaced
a minimum of 600 feet apart. Median openings shall conform to the
following design standards:
A. For median openings including left turn lanes, the storage and taper
lengths mentioned in these design criteria shall apply.
B. The median opening at the intersection of two streets shall be at least
the width of the minor right-of-way plus 10 feet. These median
openings may be wider based on lane configurations or traffic volumes.
In such cases sufficient traffic analysis and data should be presented
along with design.
Page 13 of 33 Roadway Design
Criteria
C. Variations to these criteria may be granted on a case by case basis by
the City Engineer.
6.4.12 Cul-de-sac Pavement
A. Residential minimum pavement radii for the cul-de-sac bulb as
measured to the face of curb shall be 40 feet.
B. Commercial and industrial minimum pavement radii for the cul-de-sac
bulb as measured to the face of curb shall be 45 feet.
C. Right-of-way radius shall be clear of permanent obstructions.
D. Curb radii at the transition to the cul-de-sac shall have a typical radius
of 25 feet in single family residential areas and 35 feet in all other areas
as measured at the face of curb.
E. The minimum grade line around a cul-de-sac shall be 0.70%.
F. The length of a cul-de-sac is defined as the distance from the centerline
of the intersecting pavement to the center of the cul-de-sac bulb
measured along the centerline of the street right-of-way. Maximum
length of cul-de-sac local streets for residential subdivisions shall be 600
feet. Dead end collectors and dead-end major and minor thoroughfares
shall not be allowed.
G. The City Engineer reserves the right to require shorter maximum lengths
of commercial and industrial cul-de-sacs or dead-end streets where high
traffic volumes are present.
6.4.13 The design of on street parking shall conform to the following design
criteria:
A. All on-street parking shall be parallel parking only.
B. On-street parking spaces shall be striped with white paint.
C. The width of on-street parking spaces shall be a minimum of 8 feet in
width as measured from the inside of the painted stripe to the face of
curb when allowed or approved by special design and with study by and
consultation with the Planning Department.
6.5 GATED DEVELOPMENT ENTRANCE REQUIREMENTS
Page 14 of 33 Roadway Design
Criteria
6.4.1 Gated developments shall have a median divided street that will allow for a
vehicular u-turn prior to the gate in the event that access is denied. The
turn-around shall be a minimum of eighteen feet(18') in width.
6.4.2 Entry gates shall be set back from the ROW a minimum of sixty feet(60')
to provide stacking. There shall be a minimum of forty feet (40') to the
entry keypad or first stop to allow room for the longest queue of vehicles
expected to access the gate. Length of queue shall be determined by the
development TIA and also address the turning movements into and out of
the development and if and if mitigation will be required.Impacts that could
cause backups onto the existing roadways due to the gated entrance are not
allowed.
6.4.3 The travelway shall be a minimum of twenty-four feet(24') in width. See
Figure 11.12.
6.4.4 The hinge point of the gate shall be a minimum of eighteen inches (18")
behind back of the curb.
6.4.5 Gates shall be equipped a Knox box for emergency access.
6.4.6 Vehicular gates shall not encroach on public sidewalks.
6.4.7 Any alternative designs require City Engineer approval.
100'MIN
PVT
15'x 15'CLIP 15'R 15'x 15'CLIP
t Private Street
12' %t r ' 12'
- - t - - - r T
Building Line I GATE Building Line
1 8 1 5'R
250'MINIMUM I a ` READER/KEYPAD
CENTERLINE I 1'Stop
RADIUS I 25'x25' 40'
• I ' ROW MINIMUM
I CUP STACKING
Row UP U a 74 ' ✓�
J 12'
1
11'
Public Street
FIGURE 6.4.—Gated Entrance Detail
Page 15 of 33 Roadway Design
Criteria
6.6 PUBLIC RIGHT-OF-WAY VISIBILITY REQUIREMENTS
6.5.1 Adequate sight distance at the intersection of all streets shall be assured.
This sight distance is provided through the use of a Corner Visibility
Triangle and/or a Sight Line Triangle. Construction plans for roadways
shall show both the Corner Visibility Triangle and the Sight Line Triangle
on the plan view of proposed streets. Corner Visibility Triangles shall be
dedicated as ROW and Sight Line Triangles shall be identified and
dedicated as Visibility, Access and Maintenance Easements or Reserves
(VAM's). In addition, a Sight Line Triangle must also be provided for the
following cases:
a. Where a driveway, alley, or any roadway that is controlled by a stop sign
intersects with an uncontrolled thoroughfare.
b. On any signalized intersection approach where right-turn on red operation
is permitted, a sight line triangle must be provided for the right turn driver.
6.5.2 Corner Visibility Triangle Defined:
a. The corner visibility triangle is defined at an intersection by extending the
two ROW lines from their point of intersection to a distance as shown on
Table 6.5.1. These two points are then connected with an imaginary line to
form the corner visibility triangle as shown in Figure 6.5.1. If there are no
curbs existing, then the triangular area shall be formed by extending the
property lines for a distance of thirty feet (30') from their point of
intersection.
TABLE 6.5.1: Corner Visibility Triangle Distances
Type of Roadway Type of Roadway Distance
On At (�
4 or 6 lane ALL 25'
Collector Collector 25'
Collector Local 10'
Local Local 10'
Page 16 of 33 Roadway Design
Criteria
X x
ROW
X Elx •
•
• ROW o�vialik /ROW .
FIGURE 6.5.1 —Corner Visibility Triangle for an Intersection
b. Where alleys intersect public streets, the corner visibility triangle is
measured as fifteen feet(15')along the residential street ROW and five feet
(5') along the alley ROW from the point of intersection. These two points
are then connected with an imaginary line to form the corner visibility
triangle as shown in Figure 6.5.2. The alley corner visibility triangle shall
be dedicated as ROW.
•
Loas=tw gr
ISA .
•
>ZO�►
• I •
•
FIGURE 6.5.2—Corner Visibility Triangle for an Alley
6.5.3 Sight Line Triangle Defined:
a. The sight line triangle is formed by first extending a line along the center
line of the proposed roadway or driveway that begins at the tangent curb of
the intersecting roadway and extends to its endpoint fifteen feet (15') into
the proposed thoroughfare or driveway. For the sight line triangle to the
left, construct a second imaginary line that is parallel to and five feet (5')
out from the intersecting thoroughfare's curb that begins at the centerline of
the side street and continues to the left for a distance L to its endpoint. To
complete the sight line triangle, connect the endpoints of the first two lines
as shown in Figures 6.5.3 and 6.5.4. In the case of the sight line triangle to
the right, the second imaginary line is parallel and five feet (5') out from
Page 17 of 33 Roadway Design
Criteria
the nearest edge of the conflicting traffic flow (or adjacent median in the
event of a divided roadway). It begins at the centerline of the side street
and continues to the right for a distance R to its endpoint(See Figures 6.5.3
and 6.5.4). On divided roadways with a median width greater than 30 feet,
sight line triangles shall be generated at the intersecting roadway and at the
median opening.
•
L R
Ft.
sFt ,
15 Ft
FIGURE 6.5.3: Typical Sight Line Triangle
(multi-lane approaches require similar analysis)
•
•
I •
FIGURE 6.5.4: Typical Sight Line Triangle for a Divided Thoroughfare
(multi-lane approaches require similar analysis)
Page 18 of 33 Roadway Design
Criteria
b. Distance to driver's eye for all roadways and driveways that intersect a
street is fifteen feet (15') from the intersecting curb line as shown in
Figures 6.5.3 and 6.5.4.
c. In the case where the thoroughfare contains existing horizontal curvature,
the distances L and R must be measured along the horizontal curve
TABLE 6.5.2: Sight Line Triangle Distances
SD to Right by Lanes in Cross Section
Design Speed SD to Left(1) R (ft)
V(MPH) L (ft)
2 4(2) 6(2)
30 325 325 N/A N/A
35 425 425 N/A N/A
40 525 525 N/A N/A
45 625 625 650 N/A
50 725 725 750 775
(1) Source AASHTO Green Book
(2) Manual Calculations of the Procedure in the Green Book indicate a twenty-
five-foot(25') increase in sight distance to the right for each increase in cross
section.
6.5.4 Landscaping and Obstruction Requirements for Corner Visibility and Site
Line Triangles.
a. No fence, wall, screen, sign, structure, foliage, hedge, tree, bush, shrub,
berm, driveway planting, parking, or any other item, either man-made or
natural shall be erected, planted, or maintained in a position that will
obstruct or interfere with a driver's clear line of sight within both the corner
visibility and sight line triangle (i.e., VAM's).
b. Vision at all intersections shall be clear from obstructions at elevations
between thirty inches (30") and ten feet (10') above the average gutter
elevation within each sight line triangle. Existing trees shall have a clear
trunk of eight feet (8') above average gutter elevation within each sight
triangle. Traffic control devices shall remain visible at all times in
accordance with the requirements of the TMUTCD.
6.5.5 Landscape Plan Requirements:
a. A sitework/landscape plan is required that shows the plan of the street on
both sides, and the median where necessary, of each proposed
driveway/street to the proposed development with the grades, curb
elevations, proposed street/drive locations, and all items (both natural and
man-made)within both the corner visibility and sight line triangles.
Page 19 of 33 Roadway Design
Criteria
b. This sitework/landscape plan shall show no horizontal or vertical
restrictions (either existing or future) within the corner visibility and sight
line triangles.
6.7 PAVEMENT STRUCTURE REQUIREMENTS
6.7.1 The pavement structure for all roadways outside of zoned industrial areas
shall be designed based on soil data from the site and geotechnical analysis,
anticipated traffic volume, desired service life of the proposed pavement.
The Professional Engineer of Record is responsible for ensuring that the
pavement structure is designed to withstand the anticipated loads that are
expected on the roadway. All roadways outside of zoned industrial areas
shall be designed to adequately handle the design vehicle weight. Such
criteria shall be used to design the roadway when these data, in sum,
recommend a pavement larger than the minimums below.
6.7.2 For the typical pavement section and detail for local residential streets,
minor collectors, major collectors, secondary and major thoroughfares,
refer to City's Standard Construction Details.
6.7.3 Lime determination shall be made utilizing a soil proctor from the site.
Subgrade shall be stabilized to a minimum eight inches(8")thick to reduce
Plasticity Index(PI)to twenty(20)as determined by lime series. If a PI of
20 or less cannot be obtained,then the lime treated soils must obtain a pH
of 12.4 and compacted to ninety-five percent (95%) standard proctor
density. Lime shall be applied as per TXDOT 260. Subgrade stabilization
and compaction shall extend a minimum of two feet(2')beyond the back-
of-curb or edge of pavement.
6.7.4 For the pavement structure for all public roadways inside zoned industrial
districts,the concrete pavement design and the calculation of its thickness
shall be based on AASHTO design procedures for rigid pavements and
shall be based on independent studies of projected truck traffic, projected
passenger vehicle traffic, geotechnical investigations, anticipated vehicle
loading by design vehicle and with consultation with the Planning
Department. Prior to any pavement design the developer shall consult with
the City Engineer.
6.7.5 The use of rebar dowels or the use of saw-cutting procedures to expose
existing steel in concrete pavement is required to create a minimum of 12
inches of overlap of reinforcing steel when making a connection of a
proposed concrete street to an existing concrete street or road. When the
existing street has no exposed steel the following shall apply:
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A. Dowels shall be number 4 (#4) bars, twenty-four inches (24") long,
imbedded twelve inches (12") and epoxied into the existing concrete.
Applicable spacings shall be the same as the rebar spacings mentioned
in these design criteria for the various concrete thicknesses.
6.7.6 Dead-end streets and concrete paved streets designed to be extended in the
future shall have paving headers and 15 inches (15") of reinforcing steel
exposed beyond the pavement (coated with asphalt and wrapped with
burlap), or dowel type expansion joint for future pavement tie-in.
6.7.7 Pavement extensions shall connect to the existing pavement with a
pavement undercut and a minimum steel overlap of 12 inches.
6.7.8 All concrete paving to be removed shall be removed to either an existing
joint or a saw-cut joint. Sawed joints shall be full depth of the pavement
and meet the requirements set out in this section. _
6.7.9 Materials—For all pavement materials,refer to the City's Standard Details.
6.8 REINFORCED CONCRETE PAVEMENT MATERIALS
6.8.1 Concrete—All concrete shall be a minimum of five and a half(5.5) sacks
cement per cubic yard concrete and achieve an unconfined compressive
strength of 3,500 psi at twenty-eight(28)days.
6.8.2 Reinforcing steel- Grade 60, ASTM A615, current.
6.8.3 Aggregate — Limestone shall be utilized wherever possible. Granite is
permitted only with prior approval by the City Engineer. River rock or
similar"hard" aggregates are not permitted.
6.8.4 Fly Ash — Fly ash may be permitted as an admixture with cement in
pavement or curbs. The inclusion of fly ash in pavement requires the
submission of the mix design and test history of the mix design, in addition
to prior written approval of the City Engineer. Type "C" or Type "F" fly
ash of acceptable quality and meeting requirement of ASTM C 618 may be
used as admixture in concrete mixture. When fly ash is used, store and
inspect in accordance with ASTM C 618. Do not use fly ash in amounts to
exceed 20%by weight of cementatious material in mix design.Note:When
fly ash is used, term"cement" is defined as cement plus fly ash.
6.8.5 All materials and workmanship shall conform to the Texas Department of
Transportation Standard Specifications, 2004, and the Texas Manual on
Uniform Traffic Control Devices, 2011, and any revisions thereto.
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6.9 GRADING AND LAYOUT REQUIREMENTS
6.9.1 Minimum gradient on any gutter shall be 0.30%.
6.9.2 See Chapter 5 of the Engineering Design Criteria Manual(EDCM)for inlet
spacing.
6.9.3 The maximum allowable slope for driveways shall be in accordance with
the City's Standard Construction Details.
6.9.4 The algebraic sum of grades to an inlet at an intersection should not exceed
1%.
6.9.5 All new residential and local streets poured with a curb and gutter
arrangement shall have a minimum of a 4 inch rollover, lay down curb or
approved equal. All new collector and thoroughfare streets poured with a
curb and gutter arrangement shall have the standard 6 inch stand up type
curb. A standard 6 inch curb shall be used immediately adjacent to all
storm sewer inlets; where necessary 4 inch rollover curbs shall be
transitioned to a 6 inch curb at the inlet.
6.9.6 The minimum grade line around a cul-de-sac shall be 0.70%.
6.9.7 The amount of cross slope over the pavement section shall be 2% sloping
away from the crown of road or centerline.
6.9.8 When connecting to an existing curbed street, the gutter lines for the
proposed and existing streets shall be matched.
6.9.9 Proposed top of curb elevations should be designed to match the top of the
curb at an existing street in cases where a proposed street is being
connected to an existing street.
6.9.10 Top of curb elevations shall be shown on the construction plans along with
a detail of the type of curb used.
6.9.11 Gutter line elevations for vertical curves shall be shown on the construction
drawings in cases where a railroad track is being crossed. Where railroad
crossings are not at right angles to the pavement,vertical curves should be
calculated for each curb line and should be posted at 10 foot intervals of
the centerline of the road on the construction drawings in both plan and
profile view. The grade of the railroad track shall be matched with the
centerline of the road at the intersection of the crossing.
6.9.12 All Major and Secondary Thoroughfares shall be designed so that, at all
valley locations,ponding water from the 100-year rainfall events does not
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exceed 3-inches of depth along the gutter line of inside curb. This
condition is described as"one lane passable".
6.10 TRAFFIC CONTROL DEVICES
6.10.1 Standard Type III barricades shall be permanently installed by the
developer at the end of all dead-end streets not terminating in a cul-de-sac,
and at all turnouts. These barricades shall meet at least the minimum
requirements of the TMUTCD. The erection of these Type III barricades
shall not preclude the installation of other decorative fencing or
landscaping behind the barricade for the purposes of maintaining private
property, safety, aesthetics etc.
6.10.2 Traffic signage locations,street signage locations, and pavement markings
shall be shown on the paving overall layout in the construction drawings
and shall be in compliance with the TMUCD. The construction drawings
should include pavement marking details where applicable.
6.10.3 Pavement markings shall be shown on the final construction plans for a
project. Reflectorized paint with supplemental reflectors, or approved
equal, shall be used on all major thoroughfares and on major collector
streets. Turn lanes shall have proper pavement markings. All pavement
markings shall conform to the latest edition of TMUTCD.
6.10.4 Prior to final approval of a construction project, all signage and pavement
markings shall be installed in accordance with the approved construction
plans.
6.10.5 A blue reflectorized raised pavement marker or button is required at all fire
hydrants and shall be located 6 inches off the pavement centerline toward
the fire hydrant.
6.10.6 The developer shall install requisite traffic control devices when a signal
is warranted by a traffic study.
6.10.7 Street layouts shall be designed to avoid the use multi-way stop signs in
new developments to the maximum extent practicable.
6.10.8 Developer shall install traffic control devices as warranted by an
engineering analysis or traffic study. The traffic study shall be performed
by the developer and is subject to the approval of the City Engineer.
6.11 SIDEWALKS
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6.11.1 Sidewalks meeting Americans with Disabilities Act (ADA) and Texas
Accessibility Standards (TAS) parameters are required on each side of all
public streets. The developer shall be responsible for the installation of all
sidewalks in a new development in residential or other areas as required.
This shall include but not be limited to along parks, drainage channels,
public utility easements, pipeline easements and detention ponds.
Sidewalk width and location shall be in accordance with the City's
Standard Construction Details. The developer is responsible for obtaining
any and all agreements with the public utilities for the installation of
sidewalks across applicable easements.
6.11.2 Sidewalk wheelchair ramps shall be required at all intersections and 90
degree bends in the street and shall adhere to ADA design criteria.
6.11.3 Sidewalk construction in an esplanade shall be at the esplanade noses only
and shall conform to the following parameters: A transverse concrete
sidewalk, 6 inches thick, shall be constructed in all esplanades as a
pedestrian refuge area. All concrete sidewalks in esplanades shall be 6-10
feet wide as measured from the esplanade nose. Patterned concrete or brick
stamp may be used. Any ramps associated with sidewalks in an esplanade
shall conform to ADA design criteria.
6.11.4 Sidewalk Construction shall be in accordance with the City's Standard
Construction Details.
6.11.5 Specialty sidewalks such as brick sidewalks or other non-standard
sidewalk material must receive special approval from the City Engineer.
6.12 DRIVEWAYS
6.12.1 It is desirable to minimize the number of driveways on all thoroughfares
and collect streets in order to reduce the number of conflict points and
facilitate traffic flow. It is recognized,however,that certain existing tracts
may not be able to fully comply with the following standards due to limited
frontage and other constraints. When compliance with these criteria is
precluded due to the location of driveways on adjoining properties,
attempts should be made to obtain alternative access where feasible,
including joint access driveways, access easements to adjoining properties
or access to intersecting streets.
6.12.2 A traffic impact study may be required as a part of the approval process for
driveways and other roadway access in accordance with Chapter 7 of this
manual. A traffic impact analysis(TIA),when required, shall be prepared
by an individual, group, firm or corporation having demonstrated
professional emphasis and experience in transportation planning,
engineering and in the preparation of similar analyses. The TIA document
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shall bear the seal and signature of a Texas Registered Professional
Engineer.
6.12.3 Definitions
A. Collector Streets - Street routes that have short travel distances and
collect traffic from intra-city streets and funnel it into major
thoroughfares or other collector streets.
B. Development-means the new construction of any building,structure or
improvement, or the enlargement of any exterior dimension of any
building, structure or improvement.
C. Commercial Driveway Approach - The portion of a driveway within
the public right-of-way that provides access to property on which an
office,retail or commercial center is located,to a building having more
than five dwelling units or to any driveway approach which accesses
property that is primarily used for a non-residential purpose.
D. Driveway - Entrance to and exit from premises where it is possible to
park completely off the street,and which is not open for vehicular traffic
except by permission of the owner of such private property.
E. Driveway Approach-A way or place including paving and curb returns
between the street travel lanes and private property that provides
vehicular access between the roadway and said private property.
F. Driveway Approach Width - As the term is used here, the width of a
driveway approach refers to the width of driveway pavement at the point
where the property line intersects the driveway pavement.
G. Lot - means an undivided tract or parcel of land having frontage on a
public or private street, or other approved facility contained within a
block and designated on a subdivision plat by numerical or letter
identification.
H. Intersection-The area embraced within the prolongation or connection
of the lateral curb lines, or, if none, then the lateral boundary lines of
two or more roadways, including public street, private street,
commercial driveway, residential driveway, driveway approach, alley
or combination thereof which join one another at, or approximately at,
right angles, or the area within which vehicles traveling upon different
roadways joining at any other angle may come into conflict.
I. Major Thoroughfare - Street routes that are identified as major
thoroughfares as set forth in the Major Thoroughfare Plan adopted by
City Council and as may from time to time be amended.
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J. Multi family Dwelling - means a structure containing more than two
separate units for single-family occupancy.
K. Non Residential Driveway Approach - A driveway which provides
access to property on which an office,retail or commercial or industrial
center is located, or a building having more than five dwelling units is
located or any driveway approach which accesses property that is
primarily used for a non-residential purpose.
L. Residential Driveway - means a driveway intended to provide access
from a public or private street to a single adjacent detached residential
unit.
M. Right-of-Way - Property that is publicly owned or upon which a
governmental entity has an express or implied property interest(e.g. fee
title,easement,etc.)held for a public purpose. Examples of such public
purpose include by way of example and not limitation, a highway, a
street, sidewalks, drainage facilities, sewerage and water facilities.
N. Street, Private - means a private thoroughfare, not dedicated to public
use, which provides vehicular access from a public street to more than
two residential dwelling units, or two or more commercial or industrial
buildings or parking areas.
0. Street, Public - means any public thoroughfare or right-of-way,
dedicated for public use, which provides vehicular access to adjacent
land
6.12.4 Design Requirement
A. Large speed differentials among motor vehicles traveling the same or
connecting roadways creates unsafe driving conditions. Minimizing
speed differentials through the proper design of driveway approaches
promotes driver and pedestrian safety. It is the City's policy to require
a driveway design that creates no more than a 20 mph maximum speed
differential on roadways. The goal of the City policy is to create a
balance between optimal access and safety.
Generally, as the widths of streets and vehicular speeds increase, the
number of driveway approaches should decrease. Driveway approaches
accessing major thoroughfares should be situated in a manner that
minimizes the number of potential conflict points. A single piece of
property served by multiple driveways may increase speed differentials
and is generally considered undesirable. For commercial development
shared commercial driveways shall be a requirement. Regulated access,
removing turning vehicles from the traffic stream and channelization of
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traffic should be determined on a site-specific basis, taking into
consideration the policies and requirements of the City and other
regulating entities, and following generally-accepted traffic engineering
principles.
City policy is to require turn bays and acceleration/deceleration lanes on
major thoroughfares or to utilize equally effective traffic-controlling
methods that will minimize speed differential and increase overall safety.
A sight distance analysis is required for all driveways located within a
horizontal or vertical curve of the frontage roadway
B. Driveways shall not be located within the functional areas of
intersections.
C. Driveway grades shall be minimized. The maximum algebraic change
in grade of driveways allowed on all streets is seven percent(7%)
D. At a signalized intersection in which a public street terminates at the
intersection of a connecting cross street, a driveway shall not be placed
on the cross street as to be in alignment with the terminating street. If
the requirements for driveways otherwise allow the placement of a
driveway at that location, the driveway width shall match the cross-
section of the intersecting public street.
E. Driveway approaches shall be built with a circular curb radius
connecting the raised curb of the roadway to the driveway approach in
accordance with the City of Pearland Standard Construction Details. In
order that the definition of the location of the edge of pavement for the
roadway may be maintained, driveway approach radii shall always be
designed to become tangent to the street curb line. Driveway curb
returns shall terminate within the boundaries of the lot served by the
driveway. Driveway widths shall be measured between the edges of
pavement or the face of curbs, as applicable, at the property/ROW line.
Driveway approaches within the public right-of-way shall be
constructed of the same materials as the adjacent street surface.
F. Driveways shall not be permitted in the transition area of any right-turn
lane, acceleration or deceleration lane.
G. Driveways that intersect at a mid-block median shall have the driveway
centerline intersect with the midpoint of a median opening (measured
nose-to-nose).
H. All nonconforming driveways on a lot, tract, parcel or site shall be
allowed to continue until the occurrence of one or more of the following
events:
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a. A change in use, or an increase in intensity of use (as defined
in the City Uniform Development Code), occurs such that the
site requires a ten percent (10%) increase in required parking
spaces.
b. Any modification that changes the design or function of the
existing driveway.
c. The addition of a median opening on the public street by a
developer. All driveways that are served by the new median
opening shall comply with the requirements of these standards.
Upon the occurrence of the events described, the nonconforming
status of the driveway shall cease and the driveway either
reconstructed in accordance with this ordinance, or eliminated.
I. Driveways shall not be grandfathered. Access driveways may be
permitted subject to the City Engineer approval. Permanent driveways
shall only be constructed in conjunction with the issuance of building
permit for the site.
6.12.5 Single Family Residential Driveway Requirements
A. No direct access to a thoroughfare or collector from a residential
driveway approach is allowed.
B. No lot may have more than two (2) driveways accessing the adjacent
street or streets. Side lot access is not allowed within the first one
hundred twenty feet (120') of a street serving as the entrance to a
subdivision.
C. Driveways shall be located a minimum of twenty-five feet (25') away
from the intersection of streets, measured from the curb return of the
street to the curb return of the portion of the driveway closest to the
street.
D. Circular driveways are allowed on residential lots with a street frontage
of seventy-five feet(75') or greater. A maximum of two driveways are
allowed on the street on which the seventy-five foot street frontage is
located,provided that the driveways meet all other requirements of this
chapter.
E. Residential driveways shall have a minimum curb radius of five (5')
feet. The driveway curb returns shall terminate within the boundaries
of the lot served by the driveway.
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F. Residential driveway approaches shall have a minimum width of ten
(10') feet and a maximum width of twenty(20') feet.
G. Driveway approaches within the public right-of-way shall be
constructed of the same materials as the adjacent street surface.
6.12.6 Multi-Family Residential Requirements
A. Multi-family residential developments shall meet the same driveway
standards as non-residential developments.
6.12.7 Non-Residential Driveway Requirements
A. Non-residential driveways shall be shared among different property
owners or users when necessary to maintain minimum spacing
requirements. Cross access drives shall include full drive width and
access pavement and be built at the same time as the first development.
B. Interconnectivity of multiple properties shall be maintained in the
frontage of the lot adjacent to the road.
C. Non-residential driveways shall match existing openings in medians,
whenever possible. No cut through of the left turn reservoir of a median
shall be permitted.
D. Along roadways with a continuous, two-way, left turn lane, driveways
shall not be located to require vehicles entering the driveway to cross a
delineated left turn bay or storage within the limits of the delineated left
turn bay.
E. Non-residential driveways shall be twenty-five feet (25') to thirty-five
feet(35')wide. On roadways classified as a major collector or greater,
non-residential driveways shall be thirty-five feet (35') wide unless
specifically approved by the office of the City Engineer.
F. Non-residential minimum driveway radii accessing a secondary
thoroughfare or greater shall have a radii of 35 feet. Radii for non-
residential driveways on other roadways shall be minimum 25 feet.
G. Non-residential driveways shall be placed no closer (the minimum
separation) than the following distances from adjacent streets and
driveways,unless specifically approved by the City Engineer.
Roadway Classification Minimum Separation
(As indicated on Thoroughfare Plan)
Major Thoroughfares 350'
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Secondary Thoroughfares 250'
Major Collectors 200'
Minor Collectors 165'
Local Streets 75'
The driveway separation distance is measured from the projected curb line
of the intersecting street or drive to the nearest projected curb line of the
proposed driveway.
H. In order to implement the driveway separation,shared access on all non-
residential driveways shall be required between adjacent properties.
I. On collector streets and above, without medians, non-residential
driveways shall maintain alignment with opposing driveways or meet
minimum separation stated in this section,unless specifically approved
by the office of the City Engineer.
J. The spacing and location requirements for driveways shall be applied to
both existing driveways and those shown on approved development
plans and plats. Driveway locations and requirements shall be
considered at the earliest possible stage of development of a tract.
K. Non-residential driveway connections to the public street shall be
approved and inspected by the City of Pearland.
6.12.8 Single access driveway radii shall not extend beyond the projection of a
property corner to the back of curb.
6.12.9 Driveways shall be installed in accordance with the City of Pearland
standards.
6.12.10 Driveways shall be evaluated with respect to signage, landscaping and
structures for adequate sight distances.
6.12.11 Driveways connecting to the Texas Department of Transportation
(TxDOT) roadways will require City approval and a TxDOT permit. The
TxDOT permit application shall be completed by the landowner and
submitted to the City Engineer for approval and forwarding to TxDOT.
The permit will be sent to the applicant by TxDOT upon completion.
6.9 TRAILS
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6.9.1 Trails are a specific feature that must accommodate multiple non-motorized
use (pedestrian and bicycle).
6.9.2 Trail construction must comply with all applicable Municipal, State and
Federal regulations to include TAS and ADA.
6.9.3 Trails not meeting the Design Standards will not count towards Parkland
Dedication requirements.
6.9.4 Trails in utility corridors require the written consent of the corresponding
utility company, and the approval of the City Engineer at the time of
subdivision application.
6.9.5 Removable barrier(s) will be provided to prevent unauthorized vehicular
access on to trail.
6.9.6 Bollards or operable guard rails are acceptable as removable barriers.
Bollards are to be set at 4 foot on center,on the width of the pedestrian right-
of-way.
6.9.7 Provide Trail Rule signage, pedestrian caution signage, and no motorized
vehicle warning signage where trail intersects with public roadways.
Provide signage submittal with color rendering for the City Engineer
approval.
6.9.8 Trails along street rights-of-way shall be a minimum of 10 feet wide and
constructed of concrete, or pervious concrete/materials (if approved by the
office of the City Engineer). The City may elect to contribute to the cost of
the trail if a width wider than 10 feet is deemed appropriate for that specific
location.
6.9.9 Concrete curb on roadway to be standard 6-inch concrete curb and gutter
along street frontage that abuts trail right-of-way.
6.9.10 Trails in the street rights-of-way shall include landscaping (trees and
shrubs)on each side of the trail for the remaining area of parkway,from the
back of the curb to the right-of-way line. Landscaped areas to have a
minimum depth of 4 inches of screening material over non-woven
polypropylene weed barrier pinned every 12 inches on center along
overlapped edges and seams, and every 2 feet on center in field.
6.9.11 Trails within parkland shall be constructed of concrete, except as indicated
below:
A. Proposals for alternative surface trails in parkland and areas not
designated as "Natural Open Space" may be submitted through the
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Alternative Design Process and require the approval of the office of City
Engineer prior to subdivision approval.
6.9.12 Landscaping (trees and shrubs) shall be provided at a minimum of 5 feet
wide along each side of the trail.
6.9.13 Install shrubs at a minimum spacing of 7 feet apart and provide drip
irrigation.
6.9.14 Shade trees shall be spaced a minimum of 20 feet apart and be planted 5 —
7 feet from the trail.Trees shall have a drip irrigation system provided. Tree
species shall be consistent with the street tree requirement as referenced on
the approved tree list for the City.
6.9.15 Minimum of one park bench shall be provided for each section of the trail
or spaced at a minimum 600 feet apart. Park bench must have concrete pad
to ensure compliance with accessibility requirement for companion seating.
6.9.16 Concrete trail shall be minimum 10 feet wide with minimum 6 inches thick,
reinforced with#4 rebars on 12"spacing,continuous each way,on 8 inches
of sub-grade to be scarified and compacted to minimum 95% density per
ASTM D — 1557. Concrete shall have minimum 3,000 psi strength as
specified in standard specification. Surface shall be rough broom finish.
Cross-slope shall not exceed 1%,sloped into park. Expansion joint must be
provided along back of concrete curb and be provided with 0.5 inch
expansion joint material. Control joints shall be 0.25 inch wide. The depth
of the control joint shall be 25%of the thickness of the slab. Control joints
to be placed every 10 feet on center. Expansion Cold joint every twenty feet
with 0.5 inch thick expansion joint material. Running slope of trail may not
exceed five percent(5%) in any direction.
6.9.17 Trails in natural open space areas shall remain undisturbed except for trail
corridors,as approved by the City Engineer. Use of concrete and/or asphalt
is prohibited in natural open space areas. In the event that natural open
space is disturbed outside of the designated trail corridor, the City Engineer
must be immediately notified and an inspection will be conducted to
determine the appropriate remedy. The design, surface and treatment of
trails in natural open space areas require the approval of the City Engineer
prior to subdivision approval. In natural open space areas, additional
signage advising users to stay within the designated trail corridor is
required.
6.9.18 Trail surfaces in non-right-of-way areas can be concrete or asphalt with
concrete header curbs,meeting following requirements:
A. Concrete trail shall be minimum 10 feet wide with minimum 6 inches
thick reinforced with #4 rebars on 12" spacing, continuous each way,
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on 8 inches of sub-grade to be scarified and compacted to minimum
95%density per ASTM D— 1557. Concrete shall have minimum 3,000
psi strength as specified in standard specification. Surface shall be
rough broom fmish. Cross-slope shall not exceed 1%, sloped into park.
Expansion joint must be provided along back of concrete curb and be
provided with 0.5 inch expansion joint material. Control joints shall be
0.25 inch wide. The depth of the control joint shall be 25% of the
thickness of the slab. Control joints to be placed every 10 feet on center.
Expansion Cold joint every twenty feet with 0.5 inch thick expansion
joint material. Running slope of trail may not exceed five percent(5%)
in any direction.
B. Asphalt trail shall be 10 feet wide plus(2)6 inch concrete header curbs,
for an overall width of 11 feet. Asphalt pavement shall be a minimum
of 1.5 inches thick, Type "D" HMAC, City of Pearland standards, seal
coated(2 coats), compacted to 98%minimum density as per ASTM D-
1557. Pavement structure shall be placed over a minimum 4.5 inches of
2 sacks per cubic yard cement stabilized base course material compacted
at 100%density as per ASTM D-1557 and minimum 8 inches scarified
sub-grade compacted at 95% minimum density as per ASTM D-1557.
Header curbs shall be 3,000 psi concrete strength with 2 continuous #4
rebars. Provide'/2 inch expansion joints every 20 feet and control joints
every 5 feet. Provide a broom finish.
C. Alternative trail surface proposals require the approval of the City
Engineer prior to subdivision approval. Trail must be stabilized with 2
sacks of cement per cubic yard, and shall comply with all applicable
TAS and ADA standards. Alternative Surfaces may include earthen;
organic or inorganic material,such as mulch,chat,gravel,or hardscape;
permeable pavement or other environmentally friendly material.
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CITY OF PEARLAND
CHAPTER 7
TRAFFIC DESIGN CRITERIA
ENGINEERING DESIGN CRITERIA MANUAL
December 2018
1 of 19 Traffic Design Criteria
CHAPTER 7
TRAFFIC DESIGN CRITERIA
7.1 Traffic Impact Analysis (TIA)
7.1.1 Purpose
The City requires a TIA be performed if it is determined that a proposed site
development is expected to have an impact on operation of a City street or
State road within the City limits. Such studies are necessary to define the
possible magnitude of impact(s) of the proposed development on traffic
operation of affected streets. The City may require any and all public
improvements, or a proportionate share, as recommended by the TIA be
implemented to provide accommodation of the traffic generated by the
proposed development. These guidelines detail the procedures to be
utilized when conducting a TIA for a proposed site development. These
guidelines have been developed to ensure that the TIA will include the
necessary information in a format that allows the Engineering Department
to review and make informed comments and decisions in a timely manner.
Before any work is performed on the TIA, it is required that the applicant
and engineer conduct an in-person meeting with the Engineering
Department to determine the scope of requirements for the TIA. Items to
be determined to include, but not limited to, study area and intersections,
applicable standards and methodologies,ultimate analysis year,growth rate
methodologies, nearby proposed developments to be accounted for, etc.
Final determination of all TIA parameters is subject to the discretion of the
Engineering Department.
7.1.2 Determining the Need for a Traffic Impact Analysis
A Traffic Impact Analysis is conducted to enable the City to identify the
potential impacts of a proposed development and determine any roadway
improvements necessary to provide an acceptable level of service. The TIA
should be conducted during the initial stages of the site development review
and approval process in order to adequately consider the impacts the
development will have on the City's transportation network.
A TIA is required as a part of the approval process for zoning changes;
building permits applications,subdivision platting or changes of occupancy.
A TIA is required at the earliest stage of development process to provide
technical basis for driveway placement and other traffic improvements.
A TIA, when required, shall be prepared by an individual, group, firm or
corporation having demonstrated professional emphasis and experience in
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transportation planning, engineering and in the preparation of similar
analyses. The TIA document shall bear the seal and signature of a Texas
Registered Professional Engineer.
The submitted TIA must be approved by the Engineering Department.
Approval is valid for a period of twenty-four(24) months from the date of
acceptance, provided significant changes in the development proposal or
surrounding conditions have not occurred. Renewal of the TIA may be
required by the Engineering Department,and is at the sole discretion of the
Engineering Department.
The goal of the traffic impact analysis is to ensure the level of service(LOS)
resulting from the new development conforms to the following
requirements:
Table 7.1
Existing LOS Minimum LOS
A-C* 1 LOS less than Current
D*-F Maintain Current LOS
In line with best management practices, the City aims to maintain a
minimum LOS of C. Projects that drop an existing LOS of C should
coordinate with the City to determine opportunities to maintain the current
LOS. Please reference the section 7.1.4 Funding Sources for additional
information.
Not all developments will have a significant enough impact to require a
TIA. The use of engineering judgment is necessary in making this
determination and consideration should be given not only to changes in
projected traffic volumes but also safety and capacity deficiencies which
could impact the highway system. At a minimum,a TIA shall be performed
when any of the following conditions are satisfied:
A. The proposed development is expected to generate 750 or more vehicle
trips per day(total inbound and outbound development traffic.)
B. The proposed development is expected to generate 50 or more vehicle
trips during a peak hour of the adjacent roadway.
C. Redevelopment, rezoning, additions or changes of occupancy that are
expected to increase trip generation or directional flows by 20% or
greater over existing conditions.
D. Zoning or rezoning requests.
E. Amendment to City Thoroughfare Plan.
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F. When required by the Engineering Department.
The following table lists development sizes for typical uses that are assumed
to meet the minimum threshold levels requiring a traffic impact analysis. A
traffic impact study can be required at the discretion of the City Engineer,
even if the threshold levels are not met,if based on his professional judgment
the development may have an adverse impact on traffic safety due to the
design, location or use of the proposed development.
Table 7.2
Land Use ITE Code Per Unit AM Peak PM Peak Daily
Apartments,High Rise 222 Dwelling Units 0.34 0.39 4.45
Apartments,Low Rise 221 Dwelling Units 0.32 0.41 5.44
Automobile Care Center 942 1000 SQ FT 2.83 3.51
Automobile Parts Sales 943 1000 SQ FT 2.75 2.62 16.28
Automobile Sales 841 1000 SQ FT 4.21 4.92 27.06
Bank with ATM and Drive Through 912 1000 SQ FT 14.67 20.06 100.03
Business Park 770 1000 SQ FT 1.4 1.26 12.44
Car Wash,Automated 948 1000 SQ FT 11.66
Car Wash,Self Service 947 Wash Stalls 8 8 108
Church(Sunday Value) 560 1000 SQ FT 9.99 NA 27.63
Convenience Store 851 1000 SQ FT 68.83 53.51 762.28
Convenience Store w/Gas Pumps 853 1000 SQ FT 42.19 49.59 624.2
Day Care Center 565 Enrolled Child 0.79 0.81 4.09
Discount Store 815 1000 SQ FT 5.43 5.33 53.12
Drinking Place 925 1000 SQ FT NA 15.53 NA
Hospital 610 1000 SQ FT 0.85 0.97 10.72
Hotel 310 Rooms 0.54 0.61 8.36
Industrial Park 130 1000 SQ FT 0.41 0.4 3.37
Industrial,Light 110 1000 SQ FT 0.92 0.83 4.96
Manufacturing 140 1000 SQ FT 0.81 0.79 3.93
Motel 320 Rooms 0.43 0.44 3.35
Office Building,General 710 1000 SQ FT 1.47 1.42 9.74
Office Building,Medical-Dental 720 1000 SQ FT 3.53 4.1 34.8
Office Building,Single Tenant 715 1000 SQ FT 1.78 1.71 11.25
Office Park 750 1000 SQ FT 1.49 1.33 11.07
Pharmacy w/Drive-through 881 1000 SQ FT 9.13 11.32 10_9.16
Quick Oil Change Shop 941 Service Bays 4 4.6 40
Recreational Community Center 495 1000 SQ FT 1.73 2.3 28.82
Residential,Multi-use PUD 270 Dwelling Units 0.58 0.72 7.38
Residential,Single Family 210 Dwelling Units 0.76 1 9.44
Restaurant,Fast Food 934 1000 SQ FT 50.97 51.36 470.95
Restaurant,High Turnover 932 1000 SQ FT 14.04 17.41 112.18
School,Elementary 520 1000 SQ FT 6.8 3.16 19.52
Service Station,w/Convenience Market 945 Fueling Positions 13.66 15.87 205.36
Shopping Center 820 1000 SQ FT 3 4.21 37.75
Supermarket 850 1000 SQ FT 6.67 7.6 106.78
Variety Store 814 1000 SQ FT 4.52 7.42 63.47
Warehouse,General 150 1000 SQ FT 0.22 0.24 1.74
Warehouse,Mini 151 1000 SQ FT 0.2 0.2 1.51
Values provided from 10th Edition ITE Manual-refer to ITE Manual for additional trip rates
In order to assist City in determining whether a TIA should be performed,
the applicant must fill out a Trip Generation Worksheet available online on
the City' Website. This worksheet must be submitted with each plat and/or
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site plan for developments that do not have an approved TIA. This
worksheet must be filled out using the latest edition of the Institute of
Transportation Engineers Trip Generation Manual. If the development land
use is not known at the time of the submittal then the applicant should make
assumption based on the worst-case scenario for the site. Should this be the
case, at a minimum, designer should evaluate the type of land use allowed
by the city's zoning ordinance criteria,the maximum amount of developable
land taking into account setbacks and other restrictions such as detention,
easement, etc., logical assumptions by the designer, and adjacent land uses.
If the proposed land use is not listed in the Trip Generation Manual,the City
shall require a letter from a Texas registered professional engineer,in lieu of
the trip generation worksheet, documenting the type of development
proposed and identify the number of trips generated based on either a trip
generation study performed for a similar land use or designer's professional
opinion if such report is not available. This letter report must be signed and
sealed by a registered professional engineer in the State of Texas.
7.1.3 A Traffic Impact Analysis report shall include,at a minimum,the following
information:
A. An executive summary,
B. Study purpose, objectives, and assumptions.
C. Description of the proposed development and study area,
D. Existing conditions in the area of the development,
E. Recorded or approved nearby development
F. Trip generation and trip distribution, including all count locations,
times and duration.
G. Projected future traffic volumes,
H. An assessment of the change in roadway operating conditions
resulting from the development traffic,
I. A feasibility study of placing a roundabout in lieu of a traditional
traffic signal is required.
J. If a new signal is warranted, the existing traffic corridor must be
examined for changes that need to be made in conjunction with the
new signal.
K. Recommendations for site access and transportation improvements
needed to maintain traffic flow to, from, within, and past the site at
an acceptable and safe level of service.
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L. Exhibits to show all existing, proposed and future facilities on the
site, all proposed traffic movements, and all existing, generated,
future background and proposed traffic volumes within the existing
and proposed street network
M. Appendices to include detailed site plan, existing 24-hour
directional counts,existing AM&PM peak hour turning movement
counts, all Synchro (or similar software ) report, traffic signal
warrant analysis, and digital containing Synchro (or similar
software) files, count data, and any other pertinent information.
N. List of development close to the site to be considered.
0. Consideration of phased development and transportation
improvements.
P. Identification of high accident areas for Project Category II per City
Engineer discretion and Project Category III located in Table 7.3.
Q. If modification is required of an existing traffic signal, the timing
and phasing must be examined. In addition, the implementation of
any recommendations called for in the TIA report shall be required.
Prior to preparation of a Traffic Impact Analysis report,the design engineer
is to meet with the Engineering Department to identify the study area,
define the area of influence, and non-site traffic impacts.
Three levels of study have been identified based on the number of trips that
a development is projected to generate in a 24-hour period (ADT) and
during peak hour. The following table is offered as a general guideline of
typical requirements. The Engineering Department may have further
requirements based on site-specific conditions
Table 7.3 - Levels of Traffic Impact Study
Project
Category Criteria Study Horizon Study Area
Projected site-generated ADT of 750
OR Year of
Projected site-generated peak hour All site access points,adjacent
trips of 50 per hour completion, roadways,and major intersections.
AND assuming full All signalized intersections on each
No significant modification of traffic build-out and street serving the site within 1/4 mile
signals or roadway geometry occupancy
proposed
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Projected site-generated ADT of Year of
1000-2000 completion,
OR assuming full All site access points,adjacent
Projected site-generated peak hour build-out and roadways,and major intersections.
�) trips of 100-250 per hour All signalized and major un-
OR occupancy AND cy signalized intersections on each
Installation or modification of traffic Five years after street within 1/2 mile radius
signals or roadway geometry completion
proposed, regardless of project size
Projected site-generated ADT>2000 Year of
OR completion,
Projected site-generated peak hour All site access points,adjacent
trips>250 per hour assuming full roadways,and major intersections.
OR build-out and All signalized and major un-
occupancy
Installation or modification of two or AND signalized intersections on each
more traffic signals,addition of travel Five years after street within 1 mile radius
lanes,or modification of interchange completion
proposed,regardless of project size
The TIA should incorporate all transportation and land development
information that is current and available. The ITE Traffic Engineering
Studies Handbook should be reviewed to determine if any additional
information on background data is needed
7.1.4 Funding Resources
The (TIA) may take into account the city/state/county approved traffic
improvements with dedicated funding that are scheduled for completion
prior to build out of the proposed site. Phased projects with more than one
build out year must analyze the project and determine that they meet all
LOS requirements for each phase regardless of whether a City project is
scheduled to be completed. The City Engineer will determine what
approved traffic improvements may be considered. The developer prior to
the issuance of the occupancy permit shall complete any required traffic
improvements, which have not been funded or otherwise completed by the
government agencies.
When it can be demonstrated to the satisfaction of the City that a
development will only partially contribute to the need for additional off-site
improvements, the city may approve the use of pro-rated contribution
according to the percentage of traffic added by the development.
Developments approved for pro-rata participation will need to enter into an
agreement with the City that will outline the funding participation, the cost
share mechanisms, and the adjusted timeline for completion of offsite
improvements and the development.
The City will verify that all traffic improvements to be provided by the
developer or property owner have been completed before a Certificate of
Occupancy shall be issued.
7.1.5 Submission and Review Procedures
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A preliminary trip generation worksheet of the proposed development shall
be conducted to determine if a traffic study would be required. If the
preliminary assessment indicates that a traffic study will be required, and
used in the determination of the level of study to be conducted. The trip
generation worksheet should be submitted at the earliest stage possible. In
general,the worksheet is required during the platting process for properties
with known developments,or during the permitting process for projects not
requiring a plat. If a study is required, the applicant will apply for a Traffic
Impact Analysis permit through the City's Community Development
electronic application process(eTRACKiT).Information for the application
process is available on the Engineering Website under the Traffic Impact
Analysis (TIA) Application Process document. All TIAs will be submitted
through this process.
All TIAs require a scoping meeting. TIAs submitted prior to a scoping
meeting may be rejected at the discretion of the City Engineer. The purpose
of the scoping meeting is to fully define all of the parameters of the TIA as
including but not limited to:
- Study radius
- Count locations
- Historical growth factors
- Seasonal count adjustment
- Build-out year
- Future analysis year
- Turn warrants
- Signal warrants
The City Engineer shall review the traffic impact analysis in conjunction
with the other elements of the development application. If the draft study is
not of the proper scope or is executed improperly, the applicant shall be
notified of the deficiencies and be required to submit corrections on the
same schedule that applies to the other elements of the development
application. Failure to submit corrections in a timely fashion may lead to a
postponement of the application
The submission shall include all data but not limited to the following: 1)
separate traffic count,2)all Synchro traffic modeling data and 3)all relevant
data files. These files are to be submitted with the final approved TIA.
Any traffic study will need to be revised if the proposed land use is changed
by type or size. In addition, any traffic study may need to be revised if the
study is older than two years and the City Engineer determines that the
existing conditions have changed such that it would invalidate the study
results or if the initial study assumes an incorrect build out period
7.1.6 Traffic Impact Studies Report Requirements
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A. It is recommended that along with the requirements provided in these
guidelines, the most recent version of the following resources should be
referenced during the development of a traffic impact study.
1. Highway Capacity Manual
2. Manual of Uniform Traffic Control Devices
3. Trip Generation, ITE
4. Trip Generation Handbook, ITE
5. Trip Generation User's Guide, ITE
6. Traffic Engineering Handbook,ITE
7. Manual of Transportation Engineering Studies,ITE
8. SYNCHRO Traffic Modeling Software
B. This section defines the elements that are required in a TIA. A thorough
report shall address each of the items below.
1. Introduction
a. Include a description of the site location and study area,
including a location map identifying key intersections and
other approved projects in the vicinity.
b. Development Description shall include type of land use and
the following information where applicable:
i. If residential, number and type of dwelling units
ii. If commercial or industrial, square footage and type
of development
iii. Detailed site plan
iv. Development phasing and timing
c. Selection of analysis period shall be based on the proposed
land use and the typical peak hours. Many nearby land uses
may influence peak times of a particular intersection. For
example an intersection near a hospital may peak during a
mid-afternoon shift change rather than the typical pm peak
hour. Schools, churches, hospitals or shopping centers may
impact peak periods due to their individual peaking
characteristics. Care should be given to understand the
surrounding land uses before deciding upon the peak hours.
An investigation of the daily counts prior to collecting the
peak-hour counts would allow a determination of a typical
range of peak hour traffic movements on a roadway facility.
2. Existing Conditions
a. A thorough review of available data and existing conditions
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at the site shall include at a minimum the following items:
i. A site visit by the engineer of record.
ii. Study area land use
a. Existing land use
b. Existing zoning
iii. Site access will be shown on the plan and reviewed
for sufficiency of operation and impacts to the
surrounding roadway system.
iv. Posted speed on all existing roads that may be
significantly impacted by the development.
v. Distances from existing streets, driveways, and/or
median cuts to development access.
vi. Alignment with existing streets, driveways, and/or
median cuts to development access.
vii. Intersection layout, lane usage and roadway
configuration.
viii. Traffic control devices such as traffic signals or stop
signs.
ix. Traffic signal timing and phasing — Offset times
should be shown if any coordination with adjacent
signals is being used.
x. Right of way width(s) all existing roads that may be
significantly impacted by the development.
xi. Lane width(s) for all lanes
xii. Daily and peak-hour traffic counts should be
collected for use in the traffic impact study. At a
minimum a 24-hour count should be taken on a
typical Tuesday, Wednesday or Thursday for all
roadways in the study area. However, the type of
development or local conditions may require counts
be taken on weekends. Peak-hour intersection
turning movement counts(15 min. increment)at key
intersections should also be taken. As with the daily
counts, peak-hour counts may vary. Traffic counts
used in a study should be less than one year old. The
City reserves the right to request more counts if they
are deemed necessary based on specific conditions.
The existing counts should be presented in a diagram
form for each intersection counted.
xiii. Pedestrian facilities and volumes (If appropriate)
xiv. Level of service of roadway sections and
intersections - The latest edition of the Highway
Capacity Manual(HCM)or approved traffic analysis
software (SYNCHRO) may be used. Prior approval
of alternate software may be requested from the City
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Engineer during the preliminary study meeting.
xv. Photographs may be used to document existing
conditions of the site.
3. Projected Traffic
a. The calculation of the project traffic shall be shown in
sufficient detail so that all calculations can be verified. In
addition, descriptions of the following items shall be
included in the report.
b. Site Traffic (Daily, a.m. and p.m. peak)
i. Trip Generation - List of trip generation rates and
sources of rates used for the study. The latest edition
of the Trip Generation Manual from ITE shall be
used. Calculation of trip ends assuming 100%
occupancy and development
ii. Trip Distribution and Assignment - The gravity
model or other acceptable trip distribution model can
be used to estimate site trip distribution. Trip
Distribution and Assignment can be accomplished
either manually or with applicable computer models.
A figure showing the trip distribution is required.
c. Background Traffic (Daily, a.m. and p.m. peak) - This shall
account for all approved developments in the study area as
well as area growth beyond study area. Typically this is
determined through analysis of historical trends in the
region. This should be discussed at the preliminary study
meeting. If necessary, this peak-hour data shall also be
shown in a figure similar to that for the existing traffic.
d. Reassignment rates for pass-by and diverted trips - A
procedure for calculating pass-by trips is described in
Chapter 5 of the ITE Trip Generation Handbook based on
different land use classifications. The table below shows
values to be used for the most typical land use. Reduction
for any other land use types must be thoroughly documented
and approved by the City Engineer. Internal capture can be
accounted for using the procedures described in Chapter 7 of
the ITE Traffic Engineering Handbook. Typical trip rate
reductions for pass by trips are provided in better detail in
section 7.1.7.
e. Total Traffic shall be shown combining project and
background traffic and shown in figure form for each
intersection.
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f. Future Traffic (if required) shall also be calculated and
shown in similar figure format.
4. Traffic Analysis
The following information should be included in the report
describing the detailed analysis performed for this study.
a. Projected Capacity and Level of Service(Background traffic
and total traffic)for the study horizon
i. Signalized intersection analysis.
ii. A capacity analysis using projected traffic volumes
must be conducted using the latest edition of the
Highway Capacity Manual (HCM).
iii. Traffic analysis software may be used. The latest
edition of Highway Capacity Software shall be used
or prior approval of alternate software may be
requested from the City Engineer.
iv. Un-signalized intersections and traffic signal warrant
analysis, if applicable. A capacity analysis using
projected traffic volumes must be conducted using
the latest edition of the Highway Capacity Manual
(HCM). If signalization is warranted by the traffic
signal warrants outlined in the Manual on Uniform
Traffic Control Devices (MUTCD), conduct a
complete warrant analysis and analyze the
intersection(s) as signalized intersection(s).
v. Roadway network-Impacts to LOS on key mainline
roadway links should be determined.
vi. Turning vehicle storage space needed or the
adequacy of storage space for turning vehicles at
study intersections should also be analyzed. This
analysis should consider signal phasing and overall
signal cycle length, as well as vehicle volumes.
Analysis of queuing may be required.
b. A table for each of the following information will be
provided. The AM and PM peak-hour data will both be
shown unless determined otherwise by the City Engineer.
i. Existing LOS and delay.
ii. Background LOS and delay without development.
iii. Future LOS and delay with development.
c. Site circulation and parking requirements - Driveways
should be designed considering the amount and type of
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traffic that will be using both the driveway and the adjacent
street. Adequate access for service vehicles should be
reviewed by determining the size and operating
characteristics of service vehicles, particularly the turning
radii. In addition, driveway throat lengths should also be
considered.
d. Determine impacts to nearby neighborhoods and evaluate
the potential need for any traffic calming.
e. Accident analysis may be required at intersections that
currently have a high number of accidents.
f. Additional facilities
i. Sidewalks
ii. Transit stop(s)
iii. School bus stops
5. Conclusions and Recommendations
The final section of the report should summarize the overall impact
of the development and include the following information:
a. Site access/circulation plan
b. Intersection improvements addressing, at a minimum, the
following:
i. Traffic control device(s) - modify existing or need
for new
ii. Additional lanes needed(left,right or thru)
iii. Acceleration and/or deceleration lanes
iv. Length of storage bays
v. A detailed drawing of any intersection improvements
shall be included in the report.
vi. Implementation schedule
c. Off-site improvements
i. Modification to existing traffic control device(s)
ii. Additional traffic control device(s),additional lane at
major intersections, and additional roads
iii. Other improvements if applicable
VI. Appendix
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The following appendices should be included in a bound report
submitted to the public works department:
a. Raw traffic count data
b. Printouts of analysis results
c. Photographs of site
d. Additional tables or figures not included in report
e. Professional staff qualifications and experience
f. Electronic Disc of report and data
7.1.7 Technical Notes
Trip Generation: Average trip generation rates or regression equations for
the peak hour of the adjacent street will be obtained from the current edition
of the Institute of Transportation Engineer's Trip Generation Manual.
Other local data may be acceptable provided it was collected using
recommended methodology and can be properly document.
Peak Hour: Generally, the petitioner shall use the peak one hour period
which occurs during either 7-9 A.M. or 4-6 P.M. periods or both, as agreed
to by the City Engineer and petitioner. In some cases, however, the City
Engineer may require additional hours, for example, Friday nights or
Saturday afternoon, to also be analyzed.
Directional Split: The directional split of the entering and exiting traffic
associated with the development will be derived from the ITE Trip
Generation manual unless other acceptable locally generated data is
available.
Pass-by Trips: The percent of pass-by trips shall be applied to the trips
generated by the proposed development and assigned to the adjacent street
network. This rate does not affect the proposed project's driveway volumes
but rather reassigns existing trips to movements entering and existing the
proposed development. The following pass-by trip rates have been
determined for some land uses:
Land Use Acceptable Trip Reduction
Retail>400,000 GLA 20%
Retail 100,000-400,000 GLA 25%
Retail<100,000 GLA 35%
Quality/Sit-down Restaurants 15
Fast-food Restaurants 35%
Convenience/Gas Stations 40%
Banks 15 %
Supermarket 20%
Discount Club/Warehouse Store 20%
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Diverted Linked Trips: A reassignment for diverted trips will generally
occur outside the impacted study area; therefore, for the purpose of these
traffic impact studies,diverted trips would be considered"new trips"within
the study area and can be ignored in most cases. This factor, if applicable,
will be decided during the preliminary meeting.
Internal Circulation Trips: Reductions for internal circulation trips are
applicable for projects such as shopping centers with out-lots and represents
a reduction in projected driveway trips. The internal circulation trip rate
will be agreed upon during the preliminary meeting and shall not exceed 10
percent.
Trip Distribution: The directional distribution of the generated trips
entering and exiting the proposed development via all access points must be
justified by the relative locations of other traffic generators (e.g.,
employment centers, transportation terminals, etc.) and/or trip table
information. These factors,or other factors agreed upon by the Department
of Public Works, shall be applied to the traffic generated by the proposed
development as well as the traffic generated by nearby approved projects.
Trip Assignment: The distribution factors shall be applied to the trips
generated by the proposed development and nearby approved projects and
assigned to the existing traffic on the road network providing access to the
proposed development.
Capacity Analysis: At the identified critical intersection(s),the existing and
generated traffic is to be related to the adequacy of the intersection by using
the techniques described in the latest edition of the Highway Capacity
Manual or utilizing SYNCHRO modeling software. The analysis should be
carried out for the A.M. and/or P.M. peaks, as agreed to by the City
Engineer and applicant. It is also recommended that the operational
methodology be used in the analysis of signalized intersections
Traffic Data:
A. Traffic volume data may be available from the Engineering
Department for some locations within the City. If, however,
acceptable data is not available, the petitioner is responsible for
obtaining all required data.
B. Traffic count data should be no older than one year or the City may
require new counts be collected.If,in the opinion of the Engineering
Department staff, traffic volumes have significantly increased due
to some change(s) in the traffic pattern, such as the completion of a
development project after the count was made new counts may also
be required.
C. If turning movement data is outdated or if there are locations for
which data is non-existent, data must be acquired.
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D. Intersection traffic counts conducted by the petitioner should be
comprised of a minimum of 2 hour turning movement counts
covering the peak A.M. and P.M. periods in order to allow for the
selection of the peak hour within the next fifteen minutes(e.g.,4:00-
5:00, 4:15-5:15, etc.) The inclusion of all A.M. and P.M. peak
period turning movement data is requested as part of the traffic
impact analysis.
E. Ideally the traffic analysis should be performed for the design hour
which represents the 30th highest hourly traffic volume on an annual
basis. However, most peak hour traffic volume counts in urban
areas closely approximate the 30th highest hour. Historical counts
and staff knowledge of the area will be used to judge the adequacy
of counts used by the applicant.
F. If the proposed development includes plans for the installation of a
new traffic control signal, the petitioner must conduct a Traffic
Signal Warrant Analysis. This analysis would produce
documentation that indicates the conditions at the proposed location
warrant a traffic signal by meeting the recommended minimum
warrants presented in the Manual for Uniform Traffic Control
Devices, (MUTCD). Documentation of this analysis should be
included in the appendix of the final report and should include, but
not be limited to,the methodology used,daily traffic count data used
in the analysis, and the resulting capacity analysis results at this
location.
Adequate Accommodation of Traffic: The ability of a highway system to
carry traffic is expressed in terms of volume-to-capacity (V/C) ratios and
level of service at the critical locations, usually intersections. The V/C
ratios clearly define the degree of saturation at an intersection. A V/C ratio
of 1.0 indicates that the intersection is operating at its theoretical capacity,
that is, the traffic volume demand equals the estimated number of vehicles
that may pass through the intersection in a given period of time. A value of
over 1.0 depicts a situation where the demand exceeds the intersection's
capacity and operational problems exist, either in geometries or
signalization. As the V/C ratio approaches 0.9, breakdowns in the
operational efficiency of the intersection tend to develop. When the V/C
increases above 0.9,operational breakdowns also increase in frequency and
may result in a high level of delay to motorists.
In considering mitigation measures, the change in V/C ratio and level of
service must be taken into account as well as the actual V/C values of
individual approaches and the overall intersection. If no mitigation exists
or if the improvements required are beyond what could reasonably be
expected from the applicant, then negotiations between the petitioner and
the City will be conducted to determine the level of petitioner responsibility
for improvements at the intersection.
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Level-of-service for signalized intersections is defined by the
Transportation Research Board's Highway Capacity Manual, in terms of
delay. Generally, delay is considered a measure of driver discomfort,
frustration, lost time and fuel consumption. Delay at signalized
intersections is a result of a number of factors, including the signal's cycle
length,phasing,progression in relation to other signals,traffic volumes and
the intersection's lane configuration and geometrics.
17 of 19 Traffic Design Criteria
Traffic Impact Study Checklist
Preliminary Meeting
u Contact the City Prior to beginning the study
u Analysis needed for AM and PM Weekday
u Analysis needed for Weekend
❑ Analysis needed for Mid-day Weekday or school period
Existing Conditions
❑ Existing zoning (source cited)
❑ Geometric parameters of existing roads from governing body
❑ Existing traffic counts
❑ Intersection counts (eight hours if a traffic signal warrant will be conducted)
❑ 24-hour volume counts (Tuesday to Thursday, or possibly weekend)
Site Traffic
❑ Clear and concise description for trip generation purpose (source cited)
❑ Vicinity map
❑ Site plan
❑ Trip generation using the latest edition of ITE Trip Generation Manual
❑ Trip distribution (Each step of this procedure should be clearly shown in enough
detail so that all calculations can be verified)
❑ Account for pass-by trip and internal capture reductions.
Background Traffic
❑ Clear and concise description for trip generation purpose (source cited)
❑ Vicinity maps of background sources
❑ Trip generation using the latest edition of ITE Trip Generation
❑ Trip distribution (Each step of this procedure should be clearly shown in enough
detail so that all calculations can be verified)
Traffic Analysis
❑ Existing level of service (LOS) analysis using latest version of HCS software or
other software approved by the city.
❑ Background LOS analysis using latest version of HCS software or other software
approved by the city.
o Capacity analysis for un-signalized intersection using latest version of HCS
software or other software approved by the city.
o Signal warrants analysis using Manual on Uniform Traffic Control Devices
o Capacity analysis for signalized intersection using latest version of HCS
software or other software approved by the city (if existing or warranted)
o Turning vehicle storage space (queuing)analysis
❑ Projected LOS analysis using latest version of HCS software or other software
approved by the city.
o Capacity analysis for un-signalized intersection using latest version of HCS
software or other software approved by the city.
o Signal warrants analysis using Manual on Uniform Traffic Control Devices
o Capacity analysis for signalized intersection using latest version of HCS
software or other software approved by the city. (if existing or warranted)
o Turning vehicle storage space (queuing) analysis
❑ Site circulation/parking analysis
❑ Safety/site distance analysis
❑ Discussion of additional facilities (sidewalks, bus stops, etc.)
18 of 19 Traffic Design Criteria
Conclusions and Recommendations
a Recommended site modifications (include drawings)
❑ Recommended intersection improvements (include drawings, timing methods,
etc.)
o Recommended off-site improvements (include drawings)
Documentation
o Electronic version of raw traffic count data
❑ Electronic version of Synchro traffic modeling output files and other traffic software
data used for analysis
o ITE Trip Generation summary
o Capacity analysis printouts and data file
o MUTCD Traffic Signal Warrant worksheets
Report
o Signed and stamped by registered Professional Engineer in the State of Texas
NOTE: This checklist is provided for convenience only and represents only a partial list
of the requirements for any given study.
19 of 19 Traffic Design Criteria
CITY OF PEARLAND
CHAPTER 8
STORMWATER MANAGEMENT
ENGINEERING DESIGN CRITERIA MANUAL
October 2018
Page 1 of 14 Stormwater Management
CHAPTER 8
STORMWATER MANAGEMENT
8.1 GENERAL
The City of Pearland is a Small Municipal Separate Storm Sewer System (MS4)
operator since 2008 under TPDES Phase II MS4 General Permit. Based on census
data of 2010, the City is a level III MS4 operator. This chapter provides design
guidelines to improve the Stormwater Quality through the implementation of certain
Best Management Practices(BMPs). Use of BMPs presented here does not guarantee
acceptance of a particular Storm Water Pollution Prevention Plan (SW3P) or the
effectiveness of the BMP to reduce pollutant but establishes generally acceptable
guideline. The SW3P and BMPs shall be prepared and designed in accordance with
TCEQ and other regulatory guidelines. The specification section prepared by the City
for TPDES Requirements should be referred for detailed Best Management Practices
for Erosion and Sediment Controls, Stormwater Management Plans,Waste collection
and disposal, off-site vehicle tracking, and other practices.
8.2 DEFINITIONS
8.2.1 Best Management Practices (BMPs): Schedules of activities, prohibitions of
practices, maintenance procedures, and other management practices to prevent
or reduce the pollution of waters of the United States. BMPs shall include
treatment requirements,operating procedures,and practices to control plant site
runoff,spillage or leaks,sludge or waste disposal,or drainage from raw material
storage.
8.2.2 Catch basins: Storm drain inlet and curb inlet to the City's storm drain system.
Catch basins may include a grate or curb inlet that may accumulate sediment,
debris, and other pollutants.
8.2.3 City: The City of Pearland, Texas
8.2.4 City Engineer: The City Engineer/Director of Engineering or his/her designee
8.2.5 Commercial: Pertaining to any business, trade, industry, or similar activity
8.2.6 Construction Activity: Soil disturbances, including,but not limited to clearing,
grading, and excavating; and other construction related activities (e.g.,
stockpiling of fill material, demolition, and reconstruction); but not including
routine maintenance that is performed to maintain the original line and grade,
hydraulic capacity, or original purpose of the site (e.g. the routine grading of
existing dirt roads, asphalt overlays of existing roads, the routine clearing of
existing right-of-ways, and similar maintenance activities). Regulated
Page 2 of 14 Stormwater Management
construction activity shall be defined in terms of small and large construction
activities:
(a) Small Construction Activity: Construction activity that results in land
disturbance equal to or greater than one (1) acre and less than five (5)
acres of land. Small construction activity shall also include the
disturbance of less than one (1) acre of total land area that is part of a
larger common plan of development or sale if the larger common plan
ultimately disturbs an area equal to or greater than one (1)and less than
five(5)acres of land.
(b) Large Construction Activity: Construction activity that results in land
disturbance of equal to or greater than five (5) acres of land. Large
construction activity shall also include the disturbance of less than five
(5) acres of total land area that is part of a larger common plan of
development or sale if the area common plan ultimately disturbs an area
equal or greater than five acres of land.
8.2.7 Control Measure: Any BMP or other method used to prevent or reduce the
discharge of pollutants into the MS4.
8.2.8 Conveyance: Curbs,gutters,man-made channels and ditches,drains,pipes,and
other constructed features designed or used for flood control or to otherwise
transport storm water runoff.
8.2.9 Discharge: Any addition or introduction of any pollutant, storm water, or any
other substance whatsoever into the MS4 or into waters of the United States.
8.2.10 Domestic Sewage: Human excrement, gray water, and other wastewater
discharged from the sanitary conveniences of a Facility that is free from
industrial waste.
8.2.11 Facility: Any residential or commercial building, structure, installation,
process, or activity from which there is or may be a discharge of a pollutant.
8.2.12 Final Stabilization: The status achieved when all soil disturbing activities at a
site have been completed, and a uniform perennial vegetative cover with a
density of 70 percent of the cover for unpaved areas and areas not covered by
permanent structures has been established, or equivalent permanent
stabilization measures (such as the use of riprap, gabions, or geotextiles) have
been employed.
8.2.13 Garbage:Animal and vegetable waste materials from the handling,preparation,
cooking, or consumption of food, including waste materials from markets,
storage facilities,and the handling and sale of produce and other food products.
Page 3 of 14 Stormwater Management
8.2.14 Gray Water: Animal and vegetable waste materials from the handling,
preparation, cooking, or consumption of food, including waste materials from
markets, storage facilities, and the handling and sale of produce and other food
products. .
8.2.15 Hazardous Substance: Any substance identified or listed in Table 302.4 of 40
CFR Part 302.
8.2.16 Hazardous Waste: Any substance identified or listed as a hazardous waste by
the EPA pursuant to 40 CFR Part 261.
8.2.17 Illicit Connection-Any man-made conveyance connecting an Illicit Discharge
directly to an MS4.
8.2.18 Illicit Discharge - Any discharge into an MS4 not entirely composed of storm
water, except discharges pursuant to an authorized permit and discharges
resulting from emergency firefighting activities.
8.2.19 Industrial Waste: Any liquid or solid substance that results from any process of
industry,manufacturing, mining,production, trade, or business.
8.2.20 Land Disturbance Activity: Any activity which changes the volume or discharge
rate of storm water runoff from the land surface. Land Disturbance Activity
includes grading, digging, cutting, scrapping, or excavating of soil, placement
of fill materials,paving,construction,substantial removal of vegetation, or any
activity which bares soil or rock or involves the diversion or piping of any
natural or man-made watercourse.
8.2.21 Maintenance Agreement: A formal contract between a local government and a
property owner to guarantee long-term maintenance of storm water
management practices.
8.2.22 Maximum Extent Practicable(MEP): The technology-based discharge standard,
for MS4s designed to reduce pollutants in storm water discharges that was
established by the Clean Water Act § 402(p).
8.2.23 Municipal Landfill (or Landfill): An area of land or an excavation in which
municipal solid waste is placed for permanent disposal,but which is not a land
treatment facility, a surface impoundment, an injection well, or a pile as such
terms are defined in regulations promulgated by the Texas Water Commission.
8.2.24 Municipal Separate Storm Sewer System (MS4): The system of conveyances
(including roads with drainage systems, municipal streets, catch basins, curbs,
gutters, ditches, man-made channels, or storm drains) owned and operated by
the City and designed or used for collecting or conveying storm water, but
which is not used for collecting or conveying sewage.
Page 4 of 14 Stormwater Management
a. Phase I-An MS4 permitted by the EPA after November 16, 1990.
b. Phase II -An MS4 permitted by the EPA after December 8, 1999.
8.2.25 NPDES Permit: A permit issued by EPA(or by the State of Texas,most notably
by but not limited to the TCEQ that authorizes the discharge of pollutants to
waters of the United States, whether the permit is applicable on an individual,
group,or general area-wide basis.
8.2.26 Notice of Intent (NOI): The Notice of Intent required by either the Industrial
General Permit or the Construction General Permit issued by the TCEQ.
8.2.27 Notice of Termination (NOT): A written submission from a permittee
authorized under the Construction General Permit requesting termination of
coverage.
8.2.28 Oil: Any kind of oil in any form, including, but not limited to, petroleum, fuel
oil, crude oil or any fraction thereof which is liquid at standard conditions of
temperature and pressure, sludge, oil refuse, and oil mixed with waste.
8.2.29 Person: Any individual, partnership, co-partnership, firm, company,
corporation,association,joint stock company,trust,estate,governmental entity,
or any other legal entity; or their legal representatives, agents, or assigns. This
definition includes all federal, state, and local governmental entities.
8.2.30 Premise: Any building, lot, parcel of land, or portion of land whether improved
or unimproved including adjacent sidewalks and parking strips.
8.2.31 Pollutant: Solid waste; incinerator residue; sewage; garbage; sewage sludge;
munitions; chemical waste; biological materials; radioactive materials; heat;
wrecked or discarded equipment; rock; sand; cellar dirt; or industrial,
municipal, and agricultural waste discharged into water. The term "pollutant"
shall not include tail water or runoff water from irrigation or rainwater runoff
from cultivated or uncultivated range land,pasture land, and farm land.
8.2.32: Pollution: The alteration of the physical, thermal, chemical, or biological
quality of, or the contamination of, any water in the state that renders the water
harmful, .detrimental, or injurious to humans, animal life, vegetation, or
property, or to the public health, safety or welfare, or impairs the usefulness or
the public enjoyment of the water for any lawful or reasonable purpose.
8.2.33 Release: Any spilling, leaking, pumping, pouring, emitting, emptying,
discharging, injecting, escaping, leaching, dumping, or disposing into the MS4
or the waters of the United States.
Page 5 of 14 Stormwater Management
8.2.34 Rubbish: Non-decaying solid waste, excluding ashes, that consist of (A)
combustible waste materials, including paper, rags, cartons, wood, excelsior,
furniture, rubber, plastics, yard trimmings, leaves, and similar materials; and
(B) noncombustible waste materials, including glass, crockery, tin cans,
aluminum cans, metal furniture, and similar materials that do not burn at
ordinary incinerator temperatures (1600 to 1800 degrees Fahrenheit).
8.2.35 Sanitary Sewer (or Sewer): The system of pipes, conduits, and other
conveyances which carry industrial waste and domestic sewage from Facilities,
residential dwellings, commercial buildings, industrial and manufacturing
facilities, and institutions, whether treated or untreated, to the City sewage
treatment plant(and to which storm water, surface water, and groundwater are
not intentionally admitted).
8.2.36 Sewage(or Sanitary Sewage): The domestic sewage and/or industrial waste that
is discharged into the City sanitary sewer system and passes through the
sanitary sewer system to a City sewage treatment plant for treatment.
8.2.37 Site: The land or water area where any Facility or activity is physically located
or conducted, including adjacent land used in connection with the Facility or
activity.
8.2.38 Solid Waste: Any and all garbage trash refuse and other discarded materials
held or accumulated in containers including without limitation animal and
waste materials resulting from the preparation processing or consumption of
food combustible waste materials such as paper rags cartons boxes plastics
noncombustible materials such as glass crockery and metal cans. Solid waste
shall not include Hazardous.
8.2.39 State: The State of Texas.
8.2.40 Stormwater: Stormwater runoff, snow melt runoff, and surface runoff drainage.
8.2.41 Storm Water Pollution Prevention Plan: Plan required by either the Construction
General Permit or the Industrial General Permit and which describes and
ensures the implementation of practices that are to be used to reduce the
pollutants in storm water discharge associated with construction or industrial
activity.
8.2.42 Texas Pollutant Discharge Elimination System Storm Water Discharge Permit:
A permit issued by the TCEQ, under the authority of Texas Water Code
Sections 26.027 or 26.040 authorizing the discharge of pollutants into or
adjacent water in the State.
Page 6 of 14 Stormwater Management
8.2.43 Used Oil (or Used Motor Oil): Any oil that has been refined from crude oil or
synthetic oil that,as a result of use,storage,or handling,has become unsuitable
for its original purpose because of impurities or the loss of original properties
but that may be suitable for further use and is recyclable under State and Federal
law.
8.2.44 Water Quality Standard: The designation of a body or segment of surface water
in the State for desirable uses and the narrative and numerical criteria deemed
by the State to be necessary to protect those uses, as described in Chapter 307
of Title 30 of the Texas Administrative Code.
8.2.45 Waters of the United States: All waters which are currently used, were used in
the past, or may be susceptible to use in interstate or foreign commerce,
including all waters which are subject to the ebb and flow of the tide; all
interstate waters, including interstate wetlands; all other waters the use,
degradation, or destruction of which would affect or could affect interstate or
foreign commerce; all impoundments of waters otherwise defined as waters of
the United States under this definition;all tributaries of waters identified in this
definition; all wetlands adjacent to waters identified in this definition; and any
waters within the federal definition of"waters of the United States" in 40 CFR
§ 122.2; but not including any waste treatment systems, treatment ponds, or
lagoons designed to meet the requirements of the Federal Clean Water Act.
8.2.46 Wetland: An area that inundated or saturated by surface or groundwater at a
frequency and duration sufficient to support, and that under normal
circumstances does support, a prevalence of vegetation typically adapted for
life in saturated soil conditions. Wetlands generally include swamps, marshes,
bogs, and similar areas.
8.3 ALLOWABLE STORMWATER DISCHARGES
Allowable non-storm water discharges listed in TPDES General Permit No.
TXR040000: the following non-storm water sources may be discharged from
the Phase II MS4 and are not required to be addressed in the Phase II MS4's
Illicit Discharge and Detection or other minimum control measures (MCMs),
unless it is determined by the permittee or the TCEQ to be significant
contributors of pollutants to the Phase II MS4,or such discharges are otherwise
prohibited by the MS4 operator:
1. Water line flushing (excluding discharges of hyper-chlorinated water,
unless the water is first dechlorinated and discharges not expected to
adversely affect aquatic life);
2. Runoff or return flow from landscape irrigation, lawn irrigation, and other
irrigation utilizing potable water, groundwater, or surface water sources;
3. Discharges from potable water sources not in violation of Texas Surface
Water Quality Standards, Title 30, Texas Admin. Code. Ch. 307;
Page 7 of 14 Stormwater Management
4. Diverted stream flows,which the City does not maintain,but are maintained
by the Brazoria County Drainage District No. 4;
5. Rising ground waters and springs;
6. Uncontaminated ground water infiltration;
7. Uncontaminated pumped ground water;
8. Foundation and footing drains;
9. Air conditioning condensation;
10. Water from crawl space pumps;
11. Individual residential vehicle washing;
12. Flows from wetlands and riparian habitats;
13. Dechlorinated swimming pool discharges not in violation of Texas Surface
Water Quality Standards Title 30, Texas Admin. Code. Ch. 307;
14. Street wash water, excluding street sweeper waste water;
15. Discharges or flows from emergency firefighting activities (firefighting
activities shall not include washing of trucks, run-off water from training
activities,test water from fire suppression systems, and similar activities);
16. Allowable non-storm water discharges identified in 40 CFR § 122.26 (d)
(2) (iv)(B)(1);
17. Non-storm water discharges that are identified and listed in the TPDES
Multi Sector General Permit (MSGP) TXR050000 or the TPDES
Construction General Permit(CGP)TXR150000;
18. Discharges authorized by a TPDES or NPDES permit and discharges not
required to be permitted; and
19. Other similar occasional incidental non-storm water discharges such as
spray park water.
8.4 STORMWATER POLLUTION PREVENTION PLAN (SW3P)
REQUIREMENTS
The U.S. Environmental Protection Agency (EPA) and the Texas Commission on
Environmental Quality(TCEQ)require that a Storm Water Pollution Prevention Plan
(SW3P) be prepared for construction activities. Construction plans shall show
proposed SW3P measures to control soil erosion and sediment pollution in storm
water discharges during construction. A notice of Intent (NOI) for Stormwater
Discharge Associated with Construction Activity under TPDES General Permit
(TXR150000) shall be completed and submitted to TCEQ. Copies of NOI, "Primary
and Secondary Operator"Notice shall be posted at the Project Site or at a prominent
place for public to viewing. The Contractor's office must keep and maintain the
updated SW3P. It shall be unlawful for a person/contractor to conduct any land
disturbing activity in the absence of a City issued permit authorizing such work. Such
permits include, without limitation, site work permit, building permits, grading
permits,and major construction improvement permits.
Large Construction Activity: The operator of a development shall maintain an
NPDES or TPDES permit to discharge stormwater associated with construction
Page 8 of 14 Stormwater Management
activity. The following information shall be provided to the City Engineer prior to
obtaining a construction permit from the City for that activity:
a. Copy of the Notice of Intent(NOI) submitted to the EPA or TCEQ;
b. Copy of a site plan detailing the location of erosion control measures; and
c. Copy of the construction site stormwater pollution prevention plan
(SWPPP) developed in compliance with applicable NPDES or TPDES
permit requirements.
For Small Construction Activity:The operator of a development shall comply with
an NPDES or TPDES permit to discharge stormwater associated with construction
activity. The following information shall be provided to the City Engineer prior to
obtaining a construction permit from the City for that activity:
d. A copy of the small construction site notice posted at the construction site
in accordance with applicable NPDES or TPDES permit requirements;
e. A copy of a site plan detailing the location of erosion control measures;
and
f. A copy of the construction site stormwater pollution prevention plan
(SWPPP) developed in compliance with applicable NPDES or TPDES
permit requirements.
For construction activity disturbing less than one acre: The operator of a
development shall implement and maintain a copy of the City approved erosion
control plan at the site.
The TCEQ requires that regular weekly inspections and inspections after each storm
be made of the storm water pollution measures. A record of all inspections shall be
kept. The SW3P shall be maintained throughout the entire length(time)of the project.
Should the pollution protections not be working, the Contractor shall make
adjustments in the measures to correct the problems.
Proposed SW3P shall contain minimum the following items:
(i) The proposed location of Refuse Area
(ii) The proposed location of Construction Exit with standard detail
(iii) The proposed location of concrete washout Area
(iv) The proposed location of Portable Toilets
(v) The proposed location of various BMPs
(vi) The size of affected area in acreage
(vii) The location of all outfalls for stormwater discharge
(viii) locations where temporary or permanent stabilization practices are
expected to be used
(ix) locations of construction support activities, including off-site activities,
that are authorized under the permittee's NOI, including material, waste,
borrow,fill, or equipment or chemical storage areas
Page 9 of 14 Stormwater Management
8.5 BEST MANAGEMENT PRACTICES
The SWP3 shall be prepared in accordance with TCEQ guidelines and should
include the implementation and maintenance of structural and non-structural best
management practices to reduce pollutants in storm water runoff from residential,
commercial, industrial, and Capital Improvement construction sites. The SW3P
standard details are available for download on the City's engineering webpage. It
shall be responsibility of the design engineer to ensure the appropriate use of the
standard detail as means of BMP. Listed below are recommended best management
practices that may include but are not limited to:
Non-Structural Practices
(i) Temporary seeding
(ii) Permanent planting, sodding, or seeding
(iii) Soil Retention Blanket
(iv) Buffer Zone
(v) Preservation of Natural Resources
Structural Practices
(i) Reinforced Silt Fence/silt fence
(ii) Hay Bales
(iii) Rock Filter Dams
(iv) Pipe Slope Drains
(v) Paved Flumes
(vi) Channel Liners
(vii) Sediment Basins/Detention Basin
(viii)Rock bedding at Construction exit
(ix) Curb and Gutters
(x) Velocity control devices
(xi) Erosion Control logs
All protective measures identified in the SW3P must be maintained in effective
operating condition. If, through inspections or other means, the construction site
operator determines that BMPs are not operating effectively,then the construction
site operator shall perform maintenance as necessary to maintain the continued
effectiveness of storm water controls, and prior to the next rain event if feasible.
Erosion and sediment controls that have been intentionally disabled, run-over,
removed, or otherwise rendered ineffective must be replaced or corrected
immediately upon discovery. If periodic inspections or other information indicates
a control has been used incorrectly, is performing inadequately, or is damaged,
then the operator must replace or modify the control as soon as practicable after
making the discovery. If sediment escapes the site, accumulations must be
removed at a frequency that minimizes off-site impacts, and prior to the next rain
event, if feasible. If the construction site operator does not own or operate the off-
Page 10 of 14 Stormwater Management
site conveyance,then the permittee must to work with the owner or operator of the
property to remove the sediment.
a. Rock Filter Dam Maintenance -The rock filter dam shall be inspected every
two weeks or after each 1/2" rain event and shall be replaced when the
structure ceases to function as intended due to silt accumulation among the
rocks, washout, construction traffic damage, etc. When silt reaches a depth
equal to one-third of the height of the berm or one foot,whichever is less;the
silt shall be removed and disposed of properly. When the site is completely
stabilized,the berm and accumulated silt shall be removed and disposed of in
an approved manner.
b. Stabilized Construction Exit Maintenance - When sediment has substantially
clogged the void area between the rocks, the aggregate mat must be washed
down or replaced. Periodic re-grading and top dressing with additional stone
must be done to keep the efficiency of the entrance from diminishing. See COP
specification for Stabilized Construction Exit for details.
c. Curb Inlet Protection Maintenance-Inspection shall be made by the contractor
and silt accumulation must be removed when depth reaches 2".Contractor shall
monitor the performance of inlet protection during each rainfall event and
immediately remove the inlet protections if the stormwater beings to overtop
the curb. Inlet protection shall be removed as soon as the site has reached final
stabilized.
d. Silt Fence Maintenance - Inspection shall be made after each 1/2" rainfall,
daily during period of prolonged rainfall, and at a minimum once each
week. Repair or replacement shall be made promptly as needed. Silt fence
shall be removed when the site is completely stabilized so as not to block or
impede storm flow or drainage.Accumulated sediment shall be removed when
it reaches a depth of one-third the height of the fence or 6 inches, whichever
is less. The silt shall be disposed of at an approved site and in such a manner
as to not contribute to additional siltation.
e. Erosion Control Blanket Maintenance - Erosion control blankets should be
inspected regularly for bare spots caused by weather or other events. Missing
or loosened blankets must be replaced or re-anchored. Check for excess
sediment deposited from runoff. Remove sediment and/or replace blanket as
necessary. In addition, determine the source of excess sediment and
implement appropriate measures to control the erosion. Also check for rill
erosion developing under the blankets. If found, repair the eroded area.
Determine the source of water causing the erosion and add controls to prevent
its reoccurrence.
f. Dewatering Controls Maintenance - Dewatering controls should be inspected
regularly. Dewatering discharge points should be checked for erosion. Eroded
Page 11 of 14 Stormwater Management
areas should be repaired, and erosion controls should be installed to prevent
future erosion.Dewatering pumps and sediment controls should be monitored,
at least hourly,while pumps are in operation to prevent unauthorized discharge
and to catch erosion problems or control failure. Conventional sediment
controls should be inspected at least weekly when used for continuous
dewatering, because they will become overcome with sediment more quickly
than when used to control runoff from storm events. The controls shall be
maintained according to the criteria in their respective sections.
They should be replaced when they no longer provide the necessary level of
sediment removal. Sediment filter bags should be checked to determine if they
need replacing. The bags cannot be cleaned or reused. They should be used
until they reach the manufacturer's recommended capacity. The entire bag
with sediment can be disposed of as solid waste. If a controlled location onsite
or a spoil site is available,the bag can be cut open and the sediment spread on
the ground. Only the bag is waste in this case.
g. Concrete Washout Maintenance -Concrete waste management controls should
be inspected regularly for proper handling of concrete waste. Check concrete
washout pits and make repairs as needed. Washout pits should not be allowed
to overflow. Maintain a schedule to regularly remove concrete waste and
prevent over-filling. If illicit dumping of concrete is found, remove the waste
and reinforce proper disposal methods through education of employees.
Per TCEQ requirements, erosion control and stabilization measures must be
initiated as soon as practicable in portions of the site where construction activities
have temporarily ceased. Stabilization measures that provide a protective cover
must be initiated as soon as practicable in portions of the site where construction
activities have permanently ceased. Except as provided in(A) through(C)below,
these measures must be initiated no more than 14 days after the construction
activity in that portion of the site has temporarily or permanently ceased:
A. Where the initiation of stabilization measures by the 14th day after
construction activity temporarily or permanently ceased is precluded by snow
cover or frozen ground conditions,stabilization measures must be initiated as
soon as practicable.
B. Where construction activity on a portion of the site has temporarily
ceased, and earth disturbing activities will be resumed within 21 days,
temporary erosion control and stabilization measures are not required on
that portion of site.
C. In areas where temporary stabilization measures are infeasible, the operator
may alternatively utilize temporary perimeter controls. The operator must
document in the SWP3 the reason why stabilization measures are not feasible,
Page 12 of 14 Stormwater Management
and must demonstrate that the perimeter controls will retain sediment on site
to the extent practicable.
8.6 POST CONSTRUCTION STORMWATER MANAGEMENT IN NEW
DEVELOPMENT AND REDEVELOPMENT
Post-construction storm water management in new and redevelopments should
include minimum control measures to control post-construction runoff. The
minimum control measures below are acceptable and others may be considered on
the case-by-case basis.
Minimum Control Measures:
a) Alternative Turnarounds - Dead end streets in residential subdivisions are
usually required to have an acceptable option for vehicles to turnaround, with the
circular cul-de-sac being the most common. The amount of impervious cover can
be reduced from the standard impervious cul-de-sac. It is acceptable to place a
landscaped island in the center of the cul-de-sac turnaround as long as it maintains
an acceptable turning radius. Alternative turnarounds can be applied in the design
of residential, commercial, and mixed-use development. They may be combined
with alternative pavers, biorentention areas, and other techniques in an effort to
reduce the runoff from the site.
b) Grassed Swales- A grass swale is a stable turf, parabolic or trapezoidal channel
used for water quality or to convey stormwater runoff, which does not rely on the
permeability of the soil as a pollutant removal mechanism. Grass swales are used
to reduce particulate pollutants due to settling and filtration. Particulate pollutant
removal occurs when the low velocities and shallow depths allow particulate
settling and the grass blades act to filter runoff from the water quality design storm.
Grass swales are best suited to transport and treat stormwater runoff generated
from impervious surfaces with small drainage areas. Grass swales can be used
wherever soil conditions and slopes permit the establishment and maintenance of
a dense stand of vegetative cover. Typically, swales have a minimum bottom width
of 2 feet to 10 feet and have a recommended side slope of 4:1.
c) Catch Basin Insert - Catch basins, also known as storm drain inlets and curb
inlets, are inlets to the storm drain system. Inserts can be designed to improve
water quality by removing oil and grease, trash, debris, and sediment can improve
the efficiency of catch basins. Some inserts are designed to drop directly into
existing catch basins, while others may require retrofit construction.
d) Wet Ponds - Wet ponds (a.k.a. stormwater ponds, wet retention ponds, wet
extended detention ponds) are constructed basins that have a permanent pool of
water throughout the year (or at least throughout the wet season). Ponds treat
incoming stormwater runoff by allowing particles to settle and algae to take up
nutrients. The primary removal mechanism is settling as stormwater runoff resides
Page 13 of 14 Stormwater Management
in this pool, and pollutant uptake, particularly of nutrients, also occurs through
biological activity in the pond. Wet ponds are generally on-line,end-of-pipe BMPs.
The primary pollutant removal mechanism in a wet pond is sedimentation.
Significant loads of suspended pollutants, such as metals,nutrients, sediments, and
organics, can be removed by sedimentation. Wet ponds can be used at residential,
commercial and industrial sites. Wet ponds may be single-purpose facilities,
providing only runoff treatment, or they may be incorporated into an extended
storage or a detention pond design to provide flow control.
e) Dry Ponds — Dry pond or stormwater detention pond temporarily stores
stormwater runoff, thereby reducing peak rate of runoff to the adjacent drainage
system. Although primary function of dry pond is to prevent localized flooding, it
also provide some water quality benefits and reduces downstream erosion.
8.7 MAINTENANCE OF STORMWATER FACILITY(ORDINANCE NO. 1059
The City of Pearland Maintenance of Stormwater Facility Ordinance requires the
property owner for continuous maintenance of all existing and new
detention/retention facilities. Maintenance of Stormwater Facility Ordinance No.
1059 shall be referred for the details of responsibilities, noncompliance and penalty
for violation of the ordinance.
8.8 STORMWATER AND ILLICIT DISCHARGE ORDINANCE
The City of Pearland Illicit Discharge Ordinance shall be referred for the details of
the design, construction and maintenance requirements as well as the legal
consequences for violation including penalties. Some of the specific details includes;
1. Specific prohibitions and requirements,
2. Compliance Monitoring,
3. Stormwater Discharge Associated with Construction Activities,
4. Post Construction Stormwater Runoff
Page 14 of 14 Stormwater Management
CITY OF PEARLAND
CHAPTER 9
TRAFFIC SIGNAL REQUIREMENTS
ENGINEERING DESIGN CRITERIA MANUAL
December 2018
Page 1 of 11 Traffic Signal Requirements
CHAPTER 9
TRAFFIC SIGNAL REQUIREMENTS
9.1 GENERAL
9.1.1 These standards describe the general requirements for the design and
construction or the modification of a Traffic Signal for within the City of
Pearland. Traffic roundabouts are required to be installed in lieu of a traffic
signal whenever feasible. Design for roundabouts must meet current
industry standards and individually approved by the city. A traffic signal
warrant analysis and report recommending the signal and the intersection
requirements shall be submitted. The report shall be signed and sealed by
a Registered Engineer registered in the State of Texas and in good standing.
9.1.2 The City of Pearland Engineering Department shall approve all required
traffic signals within the Pearland City limits or extraterritorial jurisdiction.
Improvements within Texas Department of Transportation(TxDOT)Right
of Way must obtain all permits and any necessary approval from TxDOT
prior to city approval.
9.1.3 All traffic signal work shall utilize the latest design guideline details
required by the State of Texas. Traffic signal design shall incorporate
energy saving measures and modular design for expansion to the maximum
extent practical.
9.1.4 This guideline serves as a reference standard, and does not supersede any
design standards set forth by the Texas Manual on Uniform Traffic Control
Devices (MUTCD), Texas Accessibility Standards (TAS) of the
Architectural Barriers Act, or any other federal, state, or local law or
regulation. The intent is to provide a standard reference to promote the
highest quality and latest engineering practices available.
9.1.5 Traffic signals shall be prepared by an individual,group,firm or corporation
having demonstrated professional emphasis and experience in
transportation planning, engineering and in the preparation of similar
analyses. The construction documents shall bear the seal and signature of a
Texas Registered Professional Engineer.
9.1.6 A paper and an electronic copy of the project as-built, in PDF and dxf
or.dwg format,and shapefile(applicable with street alignment changes)are
required prior to project acceptance into the one-year maintenance period
for all traffic signals constructed within the city limits and extra-territorial
jurisdiction of City of Pearland.
9.2 TRAFFIC SIGNAL SYSTEM DESIGN GUIDELINES
Page 2 of 11 Traffic Signal Requirements
9.2.1 Prior to beginning design, the engineer shall contact City of Pearland to
determine special design criteria, which may include pole types,
interconnection with existing signals,detection, etc.
9.2.2 The City of Pearland is standardizing the layout of the signal intersections.
All intersections for new traffic signals or reconstruction of signals shall be
equipped with a separate pedestal and mast for each direction of traffic.
9.2.3 All new traffic signals shall be decorative mast arm signals, follow City of
Pearland equipment standards and interconnected with the City of Pearland
Traffic Management Center. All traffic signals that are subject to
modification or reconstruction to the degree that the modification or
reconstruction is greater than 50% of the value of the traffic signal poles
and equipment shall be reconstructed as mast arm signals and signal
interconnection.
9.2.4 All vehicle and pedestrian signal heads shall be Light Emitting Diode(Led).
9.2.5 Pedestrian Signals shall be countdown type.
9.2.6 Battery backup shall be provided for all signals in the bottom of the signal
cabinets.
9.2.7 All traffic signal drawings shall be designed in accordance with the latest
City of Pearland design standards and specifications, Texas Department of
Transportation's (TxDOT) latest specifications and standard drawings,
including the Houston district standards.
9.2.8 All drawings shall be designed in accordance with the latest Texas Manual
on Uniform Traffic Control Devices and acceptable engineering practices
to ensure a safe and efficient operation. All traffic signal drawings shall be
designed to meet the latest state-of-the-art operational and functional
features for traffic signal systems required by the City of Pearland. Refer to
the design check list attached to the end of this chapter for minimum
requirements.
9.2.9 Any drawing that cannot provide all the required information or reaches the
capacity of one sheet is subject to additional sheets. Every drawing shall
best represent the condition of the existing and/or proposed work. The
drawings shall follow all construction design phases. All drawings shall
conform to the next phase of construction and provide a consistent design.
9.2.10 All design criteria shall be determined by the Department of Engineering.
9.2.11 Connectivity survey is required to be performed by design engineer to
Page 3 of 11 Traffic Signal Requirements
determine How to install fiber to connect the signal to the traffic system.
9.2.12 For City funded projects, typical project milestone design reviews are for
30%, 60%, 90% and 100% of the signal system design. The following is a
list of review requirements that should be included at each milestone stage.
A. The red-lined drawings and a written response of review comments from
the latest review should always be included with the next submittal. City of
Pearland reserves the right to alter the list in a manner that will best benefit
the project.
B. The in-progress (30%) design stage review shall consist of a field meeting
at the project site(s) with the consultant and the City of Pearland Project
Manager or appointed designee. The review requirements are a working
drawing showing, as a minimum, the following:
i. Right-of-way.
ii. Base line/Center line.
iii. All above ground and underground utilities. Underground utilities
shall be located as accurately as possible.
iv. Existing roadway geometric layout.
v. If making geometric improvements, show proposed geometric
improvements and signal design based on those improvements.
vi. Existing sidewalks and/or driveways.
vii. Proposed wheelchair ramps,pads, and sidewalks, if required.
viii. Proposed crosswalks, if required.
ix. Proposed service outlet location.
x. Proposed controller location.
xi. Proposed signal pole locations.
xii. Proposed pedestrian signal pole locations, if required.
C. The in-progress (60%) the review requirements are a working drawing
showing, as a minimum, the following:
i. Proposed Trafficware pod locations
ii. Proposed PTZ Camera
iii. Proposed ground box locations.
iv. Proposed signal head locations.
v. All proposed overhead signing.
vi. Proposed advance warning signs and flashers, if required.
vii. Proposed conduit, including bore locations.
viii. Proposed stop line locations.
ix. For projects with road widening, construction phasing for traffic
control should be included for a discussion in the field meeting.
x. Any construction easements or right-of-entry that may be needed.
xi. Provide documentation to City of Pearland of posted speed and 85th
Page 4 of 11 Traffic Signal Requirements
percentile speed, if known.
xii. For signal interconnect drawings,prepare pole attachment drawings
in accordance with pole owner's requirements, if required.
xiii. At this stage, the proper power company should be contacted to
request a Service Outlet and Data Statement for each intersection.
xiv. Proposed communication line routing layout to the Traffic
Management Center.
D. The 90%Design stage review shall consist of one(1)full set of construction
drawings and one (1) set of bid sheets including detailed bid items with
quantities, and the respective City of Pearland specification designations.
An electronic PDF copy of all submittals is required.
9.3 CONSTRUCTION PLAN REQUIREMENTS
9.3.1 Unless otherwise specified, all drawings are to be 11" x 17" in size. The
basic set of signal system construction drawings shall include, but is not
limited to the following categories:
A. Title Sheet and/or Index of Sheets
B. Utility notes
C. Basis of estimate
D. Condition Layout
E. Paving Layout(when applicable)
F. Pavement Marking and Signing Layout
G. Plan Layout-Need to provide station offset for each of the pole location and
indicate the length of each mast arm
H. Legend for Plan Layout
I. Signal Elevations (when applicable)
J. Anchor Bolt Details (when applicable)
K. Signal Connectivity to Traffic Management Center Sheet(when applicable)
L. Pedestrian Walkway Details
M. Notes for Plan Layout
N. Standard Detail Sheets (all required and latest)Note: All detail sheets shall
be signed and sealed.
9.3.2 This section defines the minimum elements that are required on the
construction sheets.
A. Title Sheet
i. Include intersection(s) and street name(s), Engineer, City of
Pearland Logo, etc.
ii. Date when plans are completed
iii. Vicinity map/key map location
iv. Project title including project scope and proper road names
Page 5 of 1 Traffic Signal Requirements
v. Funding for construction.
vi. Site map with north arrow.
vii. Signature block, including a block for private utility sign-offs.
B. Index Sheet
C. City of Pearland General & Construction Notes
D. TxDOT specification note,barricade note, etc.when applicable.
E. Private Utility Notes (Utility notes for all known utilities.)
F. Project-specific traffic signal notes.
G. Basis of Estimate or Summary of Traffic Signal Quantities Sheet
i. This sheet includes all wires/cables, conduits, ground boxes, span
wires,etc.providing quantities.
ii. Detailed estimated quantities per location or per specific system.
iii. Provide all detailed items with TxDOT reference item and numbers.
iv. Bid items will be discussed under bid documents.
v. Identify materials to be furnished by City of Pearland or others
(when applicable).
vi. Quantities are for estimate purposes only.
H. Existing Conditions Layout
i. Show all existing signing, (including speed limits, all approaches),
joints in pavement, type of pavement, condition of pavement (for
loops if applicable), overhead power lines,etc.
ii. Show scale
iii. Existing pavement markings and signing
iv. Existing geometries.
v. Existing utility locations.
vi. Any existing signal equipment.
vii. North arrow up or to the right.
viii. Right-of-way and easements.
I. Paving Plan(when applicable)
i. Provide a proposed design showing required wheelchair
ramps/landings to access pedestrian push buttons. These paving
improvements must comply with the current Texas Accessibility
Standards(TAS)of the Architectural Barriers Act.
ii. Provide applicable construction notes and/or paving details.
iii. Provide various notes to contractor.
Page 6 of 11 Traffic Signal Requirements
iv. Provide ramp/landing dimensions as required.
J. Proposed Traffic Signal Layout Sheet A
i. This base shall show all proposed paving improvements,signing and
striping as existing.
ii. Westbound left turn is signal head 1 and continues clockwise.
iii. Northwest corner pedestrian signal for westbound is P1 and
continues clockwise.
iv. Provide separate pole for service-meter with service enclosure and
photo electric-cell.
v. Locate controller/cabinet nearest power service.
vi. Locate controller/cabinet to not restrict sight distance for right turns
on red.
vii. LED Luminaires are required on all ornamental traffic signal poles.
Ornamental lamps are required.
viii. Trafficware pod detection system placement
K. Wiring
i. All wiring is stranded, except for#6 solid bond bare wire
ii. One(1)2/C#12 for push buttons and one(1)4/C#12 for pedestrian
signals per phase
iii. Luminaire cables, two (2) #8 XHHW, shall by-pass the
controller/cabinet and go directly to the service enclosure
iv. One(1) 7/C#12 for vehicular signals,generally one (1) 7/C#12 for
two 3-section heads and one(1) 7/C #12 for a left turn signal
v. No sign light or base light for left turn signals
vi. Three (3) 1/C #4 with one (1) #6 bare copper wire in a 2" PVC
conduit between the controller/cabinet and service enclosure
vii. Provide one (1) #6 bare copper wire in all conduits other than#14
XHHW stranded wire cable for loops
viii. Any other cable(s) shall conform to the manufacturers
recommended design
L. Conduit
i. All work shall conform to NEC codes
ii. All conduits shall be PVC except where there are risers, 45 degree
or more bends and exposed or above ground conduit
iii. Typically 1" conduit for loops (between ground box and edge of
pavement), 2" conduit for loop home runs (2/C #14). Size all
conduits by calculating the maximum fill as per NEC code
iv. Proposed conduits shall be bored and jacked under paved areas and
shall be identified on layout(s)
Page 7 of 11 Traffic Signal Requirements
v. At each pole provide a 3" (minimum) conduit from pole foundation
to ground box for future use
vi. Provide a distance of 5 feet from ground box to any pole for future
wheelchair ramps
vii. Provide long sweep 90's for conduit for fiber optic cable
M. Signal Head Mounting
i. Mast Arm: One(1)Astro brackets for each 4-section and larger
traffic signal heads
ii. Back plates are required on all signal heads
N. Legend and Notes
i. Provide this note: "Contractor shall expose utilities as needed to
install pole foundations.
ii. Right-of-way and easements.
iii. Roadway geometrics.
iv. Utilities.
v. Advance signal signing and/or flashers, if required.
vi. Trafficware Pod detection design(call out size, quantity and
distance from stop bar).
vii. Poles (meter, signal and pedestrian signal) and controller/cabinet
locations.
viii. Signal head locations.
ix. Luminaires.
x. Conduit runs and bores.
xi. Ground boxes.
xii. Stop bars.
xiii. Crosswalks.
xiv. Wheelchair ramps.
xv. Elevation callouts.
xvi. Utility contact note.
xvii. Any other signal equipment.
xviii. North arrow up or to the right.
xix. Scale.
O. Proposed Traffic Signal Layout Sheet B
i. Provide signal head schedule illustrating all vehicle signal heads and
signs attached to signal heads.
ii. Provide sign schedule and dimensions showing all overhead signs.
iii. Pole schedule and notes.
iv. Electrical schedule and notes.
v. Provide various notes to contractor and any additional notes or
Page 8 of 11 Traffic Signal Requirements
details.
vi. Overhead street name signs shall conform to the City of Pearland sign
detail(size and color).
vii. Detection phasing
P. Signal Elevations(for mast arm systems and strain pole type design)
i. Poles, signals and pedestrian signals numbered and details.
ii. Show detection or any other directional devices in their proper place.
iii. Elevation views for all approaches and proper callout.
iv. Electrical schedule callouts and guy wire details.
v. Show all conduits in foundations and call out what conduit runs
serve.
vi. Add note: "For Legend and Callouts See Traffic Signal Layout
Sheet".
a) Luminary locations.
b) Centerline of street.
c) Special notes or details.
Q. Anchor Bolt Orientation Details(for strain pole type design only)
i. Show all items located on span wires.
ii. Show angle between span wires and angle of resultant force for
each pole.
iii. Show anchor bolt orientation for each pole, two (2)bolts
compression and two (2)bolts tension.
iv. Provide same scale and orientation as Plan Layout.
a) Street names
b) North arrow up or to the right.
c) Special notes or details.
R. Signal Interconnect Sheet
i. Show all existing/proposed intersections involved.
ii. Design notes for connections.
iii. Electrical chart for interconnect cable(s).
iv. Add Note: "Refer to Intersection Layouts and Legends for Plan
Layout Sheets for Additional Information Regarding Interconnect
Cable".
v. All required details and elevation details.
vi. Intersection locations for interconnect system.
vii. North arrow up or to the right.
viii. Scale
ix. No splices will be allowed while installing and/or modifying
interconnect cables. Damaged cable will be replaced from
controller to controller.
Page 9 of 11 Traffic Signal Requirements
S. Pavement Marking and Signing Layout
A. This base shall show all proposed paving improvements as existing and
include all existing signing and striping.
B. Provide proposed design of all applicable pavement markings.
C. Signal Ahead"signs are typically provided on approaches per MUTCD
requirements.
D. Show on drawings:
i. Right-of-way and easements.
ii. Roadway geometrics.
iii. Utilities.
iv. Existing Pavement Markings and Sign details (complete).
v. Proposed Pavement Markings and Sign details(complete,including
removal of existing pavement markings and signing as needed).
vi. Construction signing.
vii. Stop bars.
viii. Crosswalks, if required.
ix. Wheelchair ramps, if required.
x. North arrow up or to the right.
xi. Legend.
xii. Scale.
xiii. Special notes.
T. Pedestrian Walkway Details
i. Current pedestrian walkway details with the following plan layout
details:
ii. Existing intersection condition.
iii. Proposed pole locations and identified.
iv. Proposed pedestrian walkway design layout.
U. Notes for Plan Layout
i. Callouts for all signals and sign types.
ii. Callouts for all signs and all sign types.
iii. Notes to reference specific sheet(s).
iv. Any note pertaining to signal design shall be included.
v. Special VIVDS specification if required.
vi. Special equipment descriptions.
vii. Maintenance of existing traffic signals and operation parameters.
Page 10 of 11 Traffic Signal Requirements
V. Standard Detail Sheets
i. Any details pertaining to the proposed signal design shall be
included.
ii. The details shall be the latest available from the City of Pearland
and TxDOT.
iii. Any necessary quantities, i.e. pole and foundation details, shall be
filled out.
iv. All detail sheets to be sealed.
W. Timings
i. All signalized intersections shall be provided with initial signal
timings.
ii. New signalized intersections that will be constructed within an
existing system shall obtain prior approval from the Director of
Public Works in order to match cycle lengths and time of day plans,
not only for the proposed signal, but corridor wide. Timing plans
shall include splits and offsets.
iii. All timing plans will be submitted to the City of Pearland for
approval prior to being implemented.
9.4 APPROVED PRODUCTS
9.4.1 All equipment and materials utilized on traffic signals within the City of
Pearland shall conform to the latest Approved Products list and shall be
subject to the approval of the Department of Engineering.
9.5 SIGNAL ACTIVATION
9.5.1 Once the signal and intersection are constructed, approved and prior to
activation and final acceptance, the traffic control change shall be notified
to the public via sign boards in each direction. The notification period shall
be for a seven (7) day period. The City shall approved the notification
message and the location and plan for the traffic control change signage.
END OF CHAPTER
Page 11 of 11 Traffic Signal Requirements
CITY OF PEARLAND
CHAPTER 10
QUALITY CONTROL & CONSTRUCTION
MATERIAL TESTING REQUIREMENTS
ENGINEERING DESIGN CRITERIA MANUAL
December 2018
Page 1 of 11 Quality Control&Construction Material
Testing
CHAPTER 10
QUALITY CONTROL & CONSTRUCTION
MATERIAL TESTING REQUIREMENTS
10.1 GENERAL
10.1.1 These standards describe the general requirements for construction material
testing on all public projects within the city limits and extra-territorial
jurisdiction of the City of Pearland.
10.1.2 The City Engineer shall approve construction plans and construction
material testing plans for public improvements within the Pearland city
limits or extraterritorial jurisdiction.
10.1.3 Construction plans for private improvements, within public right-of-ways
and public easements that connect to or affect the public infrastructure shall
be approved by the City of Pearland subject to the requirements of this
manual and are subject to review and approval using the process defined in
this manual.
10.1.4 Public projects are defined as projects that are within public rights-of-way
or public easements,projects that will be owned,operated or maintained by
public agencies or projects that are funded by public agencies.
10.1.5 It is the responsibility of the contractor to deliver a finished product in
compliance with the contract documents and applicable Federal, State and
local requirements. An independent certified testing laboratory shall be
utilized to verify contract document compliance.
10.1.6 The contractor is responsible for notification of the City and the independent
testing laboratory in accordance with the City's notification requirements.
In the event construction activity occurs without proper notification to the
City, the work in question is subject to removal and replacement in
accordance with these Standards at the discretion of the City Engineer.
10.1.7 The City Engineer shall develop and maintain an Approved Products List.
All material and appurtenances used in construction in public right-of-ways
and easements shall conform to the Approved Products List.
10.2 REFERENCES AND REQUIREMENTS
10.2.1 All construction material testing shall be performed by an independent
testing laboratory,certified by the appropriate agency for the field of testing
being conducted and supervised by a Texas Professional Engineer. All
testing shall be performed in accordance with generally accepted standards,
Page 2 of 11 Quality Control&Construction Material
Testing
including:
1. Rules and Regulations published by the Texas Commission on
Environmental Quality(TCEQ).
2. American Society of Testing Materials(ASTM)
3. American Concrete Institute(ACI)
4. The Asphalt Institute
5. Texas Department of Transportation Standard Specifications
10.2.2 Testing laboratories shall be hired by the project owner or project engineer
and contracts shall avoid conflicts of interest.
10.2.3 City projects—The costs of initial tests may be borne by the City or may be
a part of the construction contract. When initial tests indicate
noncompliance with the contract documents, the cost of subsequent
retesting and laboratory technician time shall be borne by the contractor.
The costs of inspections or testing performed exclusively for the
contractor's convenience or information shall be borne by the contractor.
10.2.4 The City shall be copied on all testing reports for public projects. Testing
reports shall be completed and submitted to the City in a timely manner and
signed by a Texas Professional Engineer.
10.2.5 It is the responsibility of the contractor to provide proper and timely
notification of construction activity to the City inspector to allow for
scheduling of the testing laboratory.
10.2.6 All retests of failed densities shall be taken within five linear feet(5')of the
failed test.
10.2.7 Moisture content on all soil density tests shall be within plus or minus two
percent (2%) to achieve a passing test, unless approval is granted by the
City Engineer based upon site-specific testing.
10.2.8 Independent testing laboratories are not authorized to revoke, modify, or
release any requirement of the specifications and they may not approve or
accept any portion of work on a project. When it appears that the material
furnished or work performed fails to meet the contract document
requirements, the testing laboratory shall promptly inform the City, in
writing or by electronic mail, of such deficiencies.
10.3 PAVEMENT SUBGRADE
Page 3 of 11 Quality Control&Construction Material
Testing
10.3.1 Pavement subgrade shall be a minimum of eight inches (8")thick and shall
be within 0.2 inches(0.2") of final lines and grade and shall vary uniformly
between points. Subgrade stabilization and compaction shall extend a
minimum of two feet (2') beyond the back-of-curb or edge of pavement.
All subgrade shall be compacted to a minimum of 95%of the maximum dry
density of the material as determined by Standard Proctor Compaction Test
ASTM D-698. Moisture content on all density tests shall be within plus or
minus two (3%)percent of optimum moisture to achieve a passing test.
10.3.2 Subgrade density tests are required at a longitudinal spacing of every 150
linear feet, (150') staggered across both lanes of traffic, on pavement cast
full width on undivided roadways. Density tests shall include the entire
cross-section of the subgrade, including the area two feet(2')outside of the
form boards. For pavement cast half-width,density tests are required every
300 linear feet(300')for each half of the roadway,with the tests offset from
tests in the adjacent half of pavement by 150 linear feet(150'). Regardless
of any other requirement, all cul-de-sacs and streets shall have a minimum
of one (1)density test within the cul-de-sac.
10.3.3 Lime depth checks are required for all pavement subgrades at the same
spacing and frequency requirement as density tests.
10.3.4 Lime determination shall be made utilizing a soil proctor from the site.
Subgrade shall be stabilized to a minimum eight inches(8")thick to reduce
Plasticity Index(PI)to twenty(20) as determined by lime series. If a PI of
20 or less cannot be obtained, then the lime treated soils must obtain a pH
of 12.4 and compacted to ninety-five percent (95%) standard proctor
density. Lime subgrade shall be mixed evenly and allowed 72 hours
between mixing to cure. Remixed lime shall have 100% of the
representative sample passing a 1 3/4" sieve and 85% of the sample passing
a 3/4"sieve and 60%passing the No. 4 sieve.
10.3.5 Prior to the application of lime slurry the roadbed shall be excavated to
subgrade, shaped to conform to the typical sections, lines and grades as
shown on plans. The material,before lime is added, shall be scarified to the
secondary grade (proposed bottom of the lime stabilized subgrade). A
"proof roll" shall be performed prior to the application of lime slurry to
identify any wet or unstable materials. Any wet or unstable materials below
the secondary grade shall be corrected, by scarifying, adding lime and
compacting until it is of uniform quality. The results of the proof roll and
any correcting action shall be documented by the testing laboratory. Place
base, surface, or seal course within 14 days after final mixing and
compacting(unless prior approval from engineer). If more than 14 days has
elapsed between final mix and cover, the lime treated subgrade will be
required to mix in an additional 3% lime slurry to the subgrade and re-
Page 4 of 11 Quality Control&Construction Material
Testing
compacted.
10.3.6 Lime operations shall not occur if the ambient temperature is 40 degrees
Fahrenheit and falling. Lime operations may occur if the ambient
temperature is 35 degrees Fahrenheit and rising.
10.3.7 Subgrade densities shall be retaken in the event of a '/2 inch or greater
rainfall or in the event the ambient air temperature falls below 32 degrees
Fahrenheit for greater than three hours.
10.3.8 Subgrade density testing shall occur after the subgrade has been cut to final
lines and grade. No subgrade/earthern material may be placed on the
subgrade after passing density tests have been achieved.
10.4 CONCRETE PAVEMENT AND UTILITY CONSTRUCTION CONCRETE
10.4.1 All concrete mix designs shall be approved by both the independent testing
laboratory and the City prior to the placement of concrete on any project.
10.4.2 Fly ash may be permitted as an admixture with cement in pavement or
curbs. The inclusion of fly ash in pavement requires the submission of the
mix design and test history of the mix design, in addition to prior written
approval of the City Engineer. Type"C"or Type "F"fly ash of acceptable
quality and meeting requirement of ASTM C 618 may be used as admixture
in concrete mixture. When fly ash is used, store and inspect in accordance
with ASTM C 618. Do not use fly ash in amounts to exceed 20%by weight
of cementatious material in mix design. Note: When fly ash is used, term
"cement" is defined as cement plus fly ash.
10.4.3 Concrete operations shall not occur if the ambient temperature is 40 degrees
Fahrenheit and falling. Concrete operations may occur if the ambient
temperature is 35 degrees Fahrenheit and rising.Place concrete only on rain
free days.
10.4.4 Place concrete that is between 40 degrees Fahrenheit and 95 degrees
Fahrenheit at the time of discharge. Do not exceed 90 minutes between
introduction of cement to aggregates and discharge. When the weather is
such that the temperature would exceed 90 degrees Fahrenheit, employ
effective means as necessary to maintain concrete temperature below 95
degrees Fahrenheit.
10.4.5 Concrete shall be tested every 150 cubic yards or less of concrete that is
placed each day. Test shall be conducted for the following criteria:
1. Entrained air—Not to exceed five percent(5%)
Page 5 of 11 Quality Control&Construction Material
Testing
2. Slump—Between two and one-half inches(2 1/2")and five inches(5"). Slip
form paving shall be a max of 3 inches(3")
3. Concrete Temperature — Not to exceed 95 degrees Fahrenheit (without
appropriate admixtures)
4. Cylinders — A minimum of one set of four cylinders to be tested for
compressive strength. 2 cylinders tested at 7 days, 2 cylinders tested at 28
days
10.4.6 Finished pavement shall have core samples taken every 300 linear feet
(300'), staggered across the roadway cross-section, and in every cul-de-sac.
Additional core samples may be required at the discretion of the City
Engineer. These core samples shall be tested to insure that the pavement
thickness meets the required project thickness. Core shall be "nine point"
measured per ASTM C174
10.4.7 Concrete cylinders,taken at the time of placement, shall be the standard for
testing for compressive strength. In limited,unique circumstances,concrete
cores of the finished pavement may be tested for compressive strength,with
prior approval by the City Engineer. In the event that concrete cores are
approved for testing, the pavement shall meet the required compressive
strength without consideration of an allowance for cut cores or any other
reduction in strength allowance.
10.4.8 Pavement shall meet both the minimum compressive strength and the
minimum thickness requirements prior to acceptance by the City Engineer.
Pavement that fails to meet both requirements shall be removed and
replaced prior to acceptance by the City.
10.4.9 In the event that pavement thickness requirements are not met, the limits of
the short pavement shall be identified through the use of additional cores at
ten foot (10') spacing on each side of the deficient pavement until the
minimum thickness requirement is met.
10.4.10 In the event a variance for deficient pavement thickness is considered by
the City, the City shall consider the extent of the thickness deficiency in
area and thickness, the concrete compressive strength, the thickness of the
subgrade, the performance of the remainder of the pavement on the project
and the performance history of the contractor on the project when reviewing
the variance. In addition,the impact of the deficient pavement on the City's
long-term maintenance costs shall be considered.
1. Accepted pavement deficient in thickness between 0.00" and 0.1" shall be
considered without a maintenance fund payment based upon the
recommendation of the design engineer, the extent and location of the
Page 6 of 11 Quality Control&Construction Material
Testing
deficient payment,verification of subgrade and other relevant specifications
being met and other relevant factors.
2. Pavement deficient in thickness between 0.11" and 0.20" shall require a
maintenance fund payment to the City of 25% of the contract unit price
times the area of deficient thickness pavement.
3. Pavement deficient in thickness between 0.21" and 0.25" shall require a
maintenance fund payment to the City of 50% of the contract unit price
times the area of deficient thickness pavement.
4. Pavement deficient in thickness greater than 0.25" shall not be considered
for acceptance.
10.4.11 Finished pavement shall have either a burlap drag or a tight (less than 12"
between centerlines)belt finish. Pavements that are excessively smooth or
rough shall be subject to removal and replacement.
10.4.12 Finished streets shall positively drain and be free from areas of standing
water(birdbaths)within 12 hours after water has ceased to flow by gravity.
Street subject to acceptance by the City for City maintenance shall be
flooded with sufficient water along the gutter line to identify potential
birdbaths prior to acceptance into the two (2) year maintenance period.
Pavement scarifying or grinding is not allowed to remediate"birdbaths"on
newly constructed pavement.
10.4.13 All concrete placed shall be uniformly sprayed with a membrane curing
compound as described in Item 526 in the TxDOT standard specification
for construction. Improper application will result in rejection of the
concrete.
10.5 ASPHALTIC CONCRETE PAVEMENT
10.5.1 Stabilized base courses shall be compacted under the controlled density
method. The base courses shall be compacted to not less than 95% of that
density obtained in Test Method Tex-114-E of the Texas Department of
Transportation testing procedures using a compactive effort of 13.26 Ft-lbs
per cubic inch.
10.5.2 All asphalt riding surface and base course density tests shall be taken a
minimum of once every 250 square yards or once for every 300 linear feet
(300')of driving lane,whichever may apply. Testing of multiple lanes shall
be staggered.
10.5.3 Finished base course grades shall not deviate more than 1/4 inch in sixteen
feet(16') from the designated grade line.
Page 7 of 11 Quality Control&Construction Material
Testing
10.5.4 Asphaltic base courses shall be installed in maximum lifts of four inches
(4"). Asphalt riding surfaces shall be placed in maximum lifts of two inches
(2"). Densities shall be taken on each lift prior to placement of subsequent
lifts.
10.5.5 Hot mix asphaltic materials, shall be at temperatures between 250 degrees
Fahrenheit and 325 degrees Fahrenheit when laid. This shall be verified by
tests. Compaction shall begin while the material is still hot and as soon as
it will bear the weight of the roller/compactor without undue displacement
or hairline cracking.
10.5.6 All asphalt roadway materials may not be placed in wet conditions or if the
ambient temperature is below 50 degrees Fahrenheit and falling. Material
may be placed if the ambient temperature,taken in the shade, is 40 degrees
Fahrenheit and rising.
10.5.7 Asphaltic materials and base courses adjacent to existing asphalt roadways
shall be placed against clean, straight edges. It is the responsibility of the
contractor to saw cut, full-depth to establish this edge and apply tackcoat to
saw cut edge, if necessary.
10.5.8 Finished pavement shall have core samples taken every 250 linear feet,
staggered across the roadway cross-section, and in every cul-de-sac.
Additional core samples may be required at the discretion of the City
Engineer. This core samples shall be tested to insure that the pavement
thickness meets the required project thickness.
10.6 CEMENT STABILIZED SAND
10.6.1 All cement stabilized sand shall be a minimum of 1.5 sacks cement per ton
sand. Cement stabilized sand shall comply with ASTM C31. Cement
stabilized sand shall achieve a minimum of 100 PSI compressive strength
at 48 hours from placement. All cement stabilized sand used for backfill or
subgrade shall be compacted to a minimum of 95% of the maximum dry
density of the material as determined by Standard Proctor Compaction Test
ASTM D-698.
10.6.2 Cement stabilized sand shall be placed and compacted within four(4)hours
of batching.
10.6.3 A minimum of two (2) random samples for compressive strength shall be
taken each week. For smaller projects, one sample may suffice with City
approval. The City Engineer reserves the right to require additional tests,
at the contractor's expense, if it is deemed necessary. In the event of a
change in supplier, samples shall be drawn on the first day of delivery from
Page 8 of 11 Quality Control&Construction Material
Testing
the new supplier, regardless of previous samples taken.
10.6.4 Cement stabilized sand samples shall be taken at the point of placement of
the cement stabilized sand and identified as to the location of the sample.
10.6.5 Cement stabilized sand densities shall be taken a minimum of every 150
linear feet of trench per lift, with a minimum of two (2) tests (one per
direction of travel) at each road crossing. When utilized as subgrade on
roadway repairs, density tests shall be taken every 100 square feet of
subgrade,with a minimum of one (1)test per repair.
10.6.6 Cement stabilized sand shall not be placed in loose lifts greater than eight
inches (8") and shall be compacted to 95% of the maximum dry density of
the material as determined by Standard Proctor Compaction Test ASTM D-
698. Moisture content on all density tests shall be within plus or minus two
percent(3%) of optimum moisture to achieve a passing test.
10.7 BEDDING,BACKFILL,EMBANKMENTS AND LOT FILL
10.7.1 No bedding, backfill, embankment or lot fill shall be placed in loose lifts
exceeding eight inches (8") in thickness without prior, written approval of
the City Engineer.
10.7.2 All trench backfill and lot fill,regardless of material, shall be compacted to
95%of the maximum dry density of the material as determined by Standard
Proctor Compaction Test ASTM D-698. Moisture content on all density
tests shall be within plus or minus two (2%) percent of optimum moisture
to achieve a passing test. Test frequency will be required as follows.
1. Bedding and density tests shall be performed a minimum of every 150 linear
feet(150') of trench in each lift. Density tests shall be offset on alternating
lifts and tests locations shall be identified by station number.
2. Embankments shall be tested at intervals not to exceed 300 linear feet(300')
of roadway and/or as conditions may require in each lift.
3. All lots shall be proof-rolled and a minimum of one density test per lift shall
occur on all lots on which fill operations have occurred. The city reserves
the right to require additional, certified density testing.
10.8 UTILITY CONSTRUCTION
10.8.1 Utility construction shall be tested in accordance with the requirements of
this chapter, the appropriate utility construction chapter and the Standard
Construction Details, as well as the requirements of any other agency
having jurisdiction.
Page 9 of 11 Quality Control&Construction Material
Testing
10.8.2 The City reserves the right to require that any storm,sanitary or water utility
line be inspected by video,and a copy of the video be submitted to the City,
prior to acceptance by the City.
Table 10.8.1 -Water Test Allowable Leakage
DIAMETER OF VOLUME PER INCH OF DEPTH ALLOWANCE LEAKAGE*
RISER OR STACK
IN INCHES INCH GALLONS PIPE SIZE IN GALLONS/MINUTE
LNCHES PER 100 FT.
1 0.7854 .0034 6 0.0039
2 3.1416 .0136 8 0.0053
2.5 4.9087 .0212 10 0.0066
3 7.0686 .0306 12 0.0079
4 12.5664 .0306 15 0.0099
5 19.6350 .0544 18 0.0118
6 28.2743 .1224 21 0.0138
8 50.2655 .2176 24 0.0518
27 0.0177
30 0.0197
36 0.0237
42 0.0276
For other diameters,multiply square of diameters by Equivalent to 50 gallons per inch
value for I"diameter inside diameter per mile per 24 hours
* Allowable leakage rate shall be reduced to 10 gallons per inch of inside diameter per mile per 24
hours,when sewer is identified as located within the 25-year flood plain.
Table 10.8.2-Acceptance Testing for Sanitary Sewers
TIME ALLOWED FOR PRESSURE LOSS FROM 3.5 PSIG TO 2.5 PSIG
Pipe Min. Length Tune I« Specification Tune for Length(L)Shown(min:sec)
LonDiam Time for Min.
Length
(in) (min:scc) Time(ft) ( c) 100 ft 150 ft 200 ft 250 ft 3005 350 ft 4005 4505 500 ft 5505 600 ft
6 5:40 398 0.8548 5:40 5:40 5:40 5:40 5:40 5:40 5:42 6:25 7:07 7:50 8:33
8 7:33 298 1.51% 7:33 7:33 7:33 7:33 7:36 8:52 10:08 11:24 12:40 13:36 15:12
10 9:27 239 2.3743 9:27 9:27 9:27 9:54 11:52 13:51 15:50 17:48 19:47 21:46 23:45
12 11:20 199 3.4190 11:20 11:20 11:20 14:15 17:06 19:57 22:48 25:39 28:30 31:20 34:11
15 14:10 159 5.3423 14:10 14:10 17:48 22:16 26:43 31:10 35:37 40:04 44:31 48:58 53:25
IR I7:00 133 7.692R 17:00 19:14 25:39 32:03 38:28 44:52 51:17 57:42 64:06 70:31 76:56
21 19:50 114 10.4708 19:50 26:11 34:54 43:38 52:21 61:05 69:48 78:32 R7:15 95:59 104:42
24 22:40 99 13.6762 22:48 34:11 45:35 56:59 68:23 79:47 91:10 102:34 113:58 125:22 136:46
27 25:30 8R 17.3089 28:51 43:16 57:42 72:07 86:33 100:58 115:24 129:49 144:14 158:40 173:05
30 28:20 80 21.3690 35:37 53:37 71:14 89:02 106:51 124:39 142:28 160:16 178:05 195:53 213:41
33 31:10 72 25.8565 43:06 64:38 86:11 107:44 129,17 150:50 172:23 193:55 215:28 237:01 258:34
Table 10.8.3-Minimum Testing Times for Low Pressure Air Test
Page 10 of I l Quality Control&Construction Material
Testing
PIPE MINIMUM LENGTH FOR TIME FOR
DIAMETER TIME MINIMUM TIME LONGER LENGTH
(INCHES) (SECONDS) (FEET) (SECONDS)
6 340 398 0.855(L)
8 454 298 1.520(L)
10 567 239 2.374(L)
12 680 199 3.419(L)
15 850 159 5.342(L)
18 1020 133 7.693 (L)
21 1190 114 10.471 (L)
24 1360 100 13.676(L)
27 1530 88 17.309(L)
30 1700 80 21.369(L)
33 1870 72 25.856(L)
Table 10.8.4—Vacuum Test Time Table
TIME IN SECONDS BY PIPE DIAMETER
DEPTH IN FEET
48" 60" 72"
4 10 13 16
8 20 26 32
12 30 39 48
16 40 52 64
20 50 65 80
24 60 78 96
* 5.0 6.5 8.0
*Add T times for each additional 2-foot depth.
(The values listed above have been extrapolated from ASTM C 924-85)
END OF CHAPTER
Page 11 of 11 Quality Control&Construction Material
Testing
CITY OF PEARLAND
CHAPTER 11
GRAPHIC STANDARDS & DRAWING REQUIREMENTS
ENGINEERING DESIGN CRITERIA MANUAL
December 2018
Page 1 of 12 Graphic Standards&Drawing
Requirements
CHAPTER 11
GRAPHIC STANDTARDS & DRAWING REQUIREMENTS
11.1 GENERAL
11.1.1 These standards describe the general requirements for construction plan graphics and
drawing layering requirements.
11.1.2 The Engineering Department shall approve construction plans for all public
improvements within the Pearland City limits or extraterritorial jurisdiction.
11.1.3 Construction plans for private improvements,within public right-of-ways and public
easements that connect to or affect the public infrastructure shall be approved by the
Department of Engineering subject to the requirements of this manual and are subject
to review and approval using the process defined in this manual.
11.1.4 In addition to the traditional paper format, all as-build construction plans shall be
submitted to the Engineering Department in electronic format. GIS features class
within geodatabase or shapefiles(ESRI format)and AutoCAD formats are required.
See GIS and AutoCAD graphics standards below.
11.2 GIS STANDARDS AND DATA REQUIREMTENS
The City now requires GIS files on all projects.CAD files will not be accepted as a substitute,
however may be requested on a project bases
11.2.1 Preferred Method of Delivery
All Files shall be delivered in electronic format by either CD,USB Drive,or Drop
Box.City email systems have a limit of 5MB for external correspondence,and do
not allow for sending or receipt of.ZIP files.
11.2.2 Acceptable Formats,all formats shall include a layer file to maintain linetypes:
1. ESRI File Geodatabase
2. ESRI Shape files(.SHP)
11.2.3 GIS Coordinate System&Projections
All GIS information shall be provided in the following coordinate system:
Coordinate system: NAD 1983 State Plane Texas South Central FIPS
4204 Feet
Geographic Coordinate System: GCS_North_American_l983
Datum:D_North American 1983
WKID: 2278
Grid Units
Projection: Lambert Conformal Conic
11.2.4 Minimum Information Requirements
GIS files shall contain at minimum the information provided below. Additional
layers or information may be required based on the complexity of the project and the
Page 2 of 12 Graphic Standards&Drawing
Requirements
work completed. These additional layers will be identified and requested by either
the Engineering Department of the GIS department.
1) Parcels—lot lines and easements
2) Platted Subdivision outline boundary
3) Street Centerlines—Street ROW centerline
4) Water lines-Distribution layout and Attributes
a) Size(numeric field)
b) Material(text field)
c) Date Constructed(date field)
5) Water points and Attributes
a) Hydrants
i) Type(text field)
b) Valves
i) Size—(numeric field)
c) Blow off Valves
i) Size—(numeric field)
d) Meter Boxes
i) Single or Double meter(numeric field)
e) Reducers
i) Size(numeric field)
6) Sanitary Sewer lines (and Force mains) - Collection layout and
Attributes
a) Size(numeric field)
b) Material(text field)
c) Date constructed(date field)
7) Sanitary Sewer points and Attributes
a) Manholes
i) #of pipes(numeric field)
ii) Material(text field)
iii) Invert Elevation(numeric field)
iv) Inflow Protector(0 or 1)
b) Lift stations
i) Depth(numeric field)
c) Clean outs
d) WACS
e) FM Air Relief Valves
8) Storm Sewer lines and Attributes
a) Size(numeric field)
b) Material(text field)
c) Date constructed(date field)
9) Storm Sewer points and Attributes
a) Manholes
i) Material(text field)
ii) Date constructed(date field)
iii) Invert Elevation
b) Inlets
i) Type(text field)
10) Pavement outline
11) Side Walks
12) Light Poles
Page 3 of 12 Graphic Standards&Drawing
Requirements
11.2.5 City Of Pearland GIS Layers
The City maintains a diverse database of current information. These files are
available for download and to be used as a reference. The address to these files is
provided below:
http://copgisweb.ci.pearland.tx.us/web/clis-data.htm
11.3 CAD STANDARDS AND DATA REQUIREMENTS
The City now requires GIS files on all projects.CAD files will not be accepted as a substitute,
however may be requested on a project bases.
11.3.1 Preferred Method of Delivery
All Files shall be delivered in electronic format by either CD,USB Drive,or Drop
Box.City email systems have a limit of 5MB for external correspondence,and do
not allow for sending or receipt of.ZIP files.
11.3.2 Acceptable Formats,all formats shall include a layer file to maintain linetypes:
1. DXF(Drawing Exchange Format,Version 2017 or earlier)
2. DWG(Autodesk AutoCAD,version 2017 or earlier)
11.4 AUTOCAD DRAWING LAYER REQUIREMENTS
As built construction drawings are to be provided with the construction information provided
in layers according the order show in Table 11.4.1. Additional layers may be added as
necessary
Table 11.4.1:Layer Symbology for Construction Plans
LAYER LAYER NAME DESCRIPTION
1 CL Centerline
2 ROW Right of Way
3 LOTLINE_PRO Lot Lines/Reserves(Proposed)
4 BOUNDARY Boundaries
5 BMARK City of Pearland Benchmark
6 LOTNOS Lot Numbers/Block Names
7 SUBDIVNM Subdivision Names/Section Numbers
8 STREETNM Street Names
9 WLINES_PRO Water Lines (Proposed)
10 FHYD_PRO Fire Hydrants(Proposed)
11 WVALVES_PRO Water Valves(Proposed)
12 WTEXT_PRO Water Line Text(Proposed)
13 SSLINES_PRO Sanitary Sewer Lines (Proposed)
14 SSMH_PRO Sanitary Sewer Manholes(Proposed)
15 SSFM_PRO Sanitary Sewer Force Main (Proposed)
16 LS_PRO Liftstation (Proposed)
17 SSTEXT_PRO Sanitary Sewer Text(Proposed)
18 STORMLINE_PRO Storm Sewer Lines(Proposed)
Page 4 of 12 Graphic Standards&Drawing
Requirements
19 STORMMH_PRO Storm Sewer Manholes(Proposed)
20 STORMIN_PRO Storm Sewer Inlets(Proposed)
21 STORMCVT_PRO Storm Sewer Culverts(Proposed)
22 STORMTEXT_PRO Storm Sewer Text(Proposed)
23 DITCH Drainage Ditch
24 TOPO Topography
25 UTIL_PRO Utilities(Proposed)
26 LAKES Lakes/Ponds etc.
27 STREAM Creeks, Bayous, Rivers etc.
28 CANAL Canals
29 RR Railroad
30 CITYLIM City Limits Line
31 COUNTYLN County Lines
32 ETJ ETJ Lines
33 NOTES Notes/Miscellaneous Text
37 UTIL_EXI Utilities(Existing)
35 LOTLINE_EXI Lot Lines/Reserves(Existing)
36 WLINES_EXI Water Lines(Existing)
37 FHYD_EXI Fire Hydrants(Existing)
38 WVALVES_EXI Water Valves(Existing)
W
39 TEXT_EXI Water Line Text(Existing)
40 SSLINES_EXI Sanitary Sewer Lines (Existing)
41 SSMH_EXI Sanitary Sewer Manholes(Existing)
42 SSFM_EXI Sanitary Sewer Force Main (Existing)
43 LS_EXI Lift station (Existing)
44 SSTEXT_EXI Sanitary Sewer(Existing)
45 STORMLINE_EXI Storm Sewer Lines(Existing)
46 STORMMH_EXI Storm Sewer Manholes(Existing)
47 STORMIN_EXI Storm Sewer Inlets(Existing)
48 STORMCVT_EXI Storm Sewer Culverts(Existing)
49 STORMTEXT_EXI Storm Sewer Text(Existing)
50 SIGN_EXI Street Sign (Existing)
51 SIGN—PRO Street Sign (Proposed)
52 SIGN—TXT Street Sign Text
53 STLIGHT_PRO Street Lights(Proposed)
54 STLIGHT_EXI Street Light(Existing)
55 STLIGHTXT Street Light Text(Proposed)
11.5 GIS GRAPHIC STANDARDS
The following graphic standards shall apply to all construction plans submitted for approval
within the city limits and extra-territorial jurisdictions.
Page 5 of 12 Graphic Standards&Drawing
Requirements
GRAPHIC STANDARDS'-EXISTING IMPROVEMENTS (Continued) 11L_LC
C
Water Line z••t"y Omle)wwrm_ 0 7
r I
3'Ora Lamed NNW 7
Sanitary Sewer Line zr Owl e.nr.)ei s""'sghs 0 3
30'(.d Low)1 .Ii J
Storm Sewer Une se(«*wadi_. 111•••••-..,,, 0 0
r r
3r(war Large)w,.s...rJ
SLG
Iron Pipe or Iron —0- 0 0 Water Valve w=v' 0 0
Rod Monuments (Gate)
(Red Ink
for
Property Corner) sr.w.v
Water Valve 0 0
(Butterfly)
Point Of Inter- O O CH.
section (P.I.)
Lava
Fire Hydrant 0 0
Point of Curve ,O 0 0
(P.C.) or Point / Tapping Sleeve rsay.
0 0
of Tangency (P.1.) / & Valve _T
Reducer r /T►r 0 0
Power Pole -fir' 0 0
Round Connections r 0 7
Power Pole Down Guy 1- 0 0 H
ar Sanitary Sewer Ca. 11.11.Gas Meter O 0 0 Cleanout and —0----411-— 0 0
Sanitary Sewer Manhole
Gas Valve .O a.v 0 0
ILK
Storm Sewer • 0 0
Header ® 0 0 Manhole
r v-r t.
Storm
Buildingisonsimme
O O 1ISewer 0 0
1-my.R sum. •c-7' 'o-r 'b-r
��r
Tree ��:� 0 0uco.
•e
Culvert Pipe __D 0 2
Hedge 0 0
r Top of Curb or 'c_ ) 0 2
Water Meter t 0 O Gutter Line rii-T "
l---1
Contour Line �.---,,f— 0 0
TECHNICAL PEN LME WEIGHT/ METRIC
Wr NUMBER WIDTH
0 0 0.014' .35mm
1 1 0.020• .50mm LEGS
2 2 0.024' .80mm IIT`LK WEIGHT
3 3 0.031' .80mm ID=UNE COOS
4 4 0.047' 1.20mm
6 6 0.055' 1.40mm
Page 6 of 12 Graphic Standards&Drawing
Requirements
GRAPHIC STANDARDS' EXISTING IMPROVEMENTS (Continued)
1.2 Profile View WT LC
North or East Property Line ---- ---- 1 5
South or West Property Line •
-- 1 6
North or East Ditch or Curb - - 1 7
South or West Ditch or Curb - 1 3
Center Line of Right—of—Way 1 4
North or East Culvert r— _ _ _ _ J 1 2
South or West Culvert C = _ _ _ J 1 2
H.L.& P Co. Conduit b NIA P. Co. taro a 1 6
1 0
Gas Line S d- H.R. Ent x Ga. ) 1 1
1 0
Western Union b western Union ) 1 1
0
S.W.B Telephone Conduitw.aT. d MCO 1 2
1 o
Water Line PT—dot 1 7
1 0
6 Exist. 24- (and smaller) San. Sow. 8 1 3
Wastewater Line _ _ 1 0
Exist 30' (and Larger) San. Sar. 8 1 3
1 0
SExist. 24- (and smatter) Sims Sow. 8 1 0
Storm Sewer Line 10
EARL 30' (and smaller) stn. Sow. 8 1 0
���allJl 1 0
NOTE: Pipe less than four inches (4") in diameter need not be
shown in profile.
TECHNICAL PEN -UNE WEIGHT/
WT NUMBER WIDTH METRIC
0 0 0.014" .35mm LEGEND
1 1 0.020" .50mm WT= LINE WEIGHT
2 2 0.024" .60mm LC= LINE CODE
3 3 0.031" .80mm
4 4 0.047" 1.20mm
6 6 0.055" 1.40mm
Page 7 of 12 Graphic Standards&Drawing
Requirements
GRAPHIC STANDARDS.-EXISTING IMPROVEMENTS (Continued)
1.2 Profile View (Cont.) WT LC
Electrical Co. Manhole ______I I_______ 1 6
Telephone/Comm. Manhole il it_ 1 2
Sanitary Sewer Manhole 1 3
and Cleanout — —
Storm Sewer Manhole 1 0
Waterline Manhole _ L_ _ 1 7
TECHNICAL PEN UNE WEIGHT/
WI NUMBER WIDTH METRIC
0 0 0.014" .35mm LEGEND
1 1 0.020" .50mm W1= LINE WEIGHT
2 2 0.024" .60mm LC= UNE CODE
3 3 0.031" .80mm
4 4 0.047" 1.20mm
6 6 0.055" 1.40mm
Page 8 of 12 Graphic Standards&Drawing
Requirements
•
GRAPHIC STANDARDS.-PROPOSED IMPROVEMENTS
2. The following standards are to be used for all proposed water line
improvements. Use line weight 3 for all proposed improvements.
NI fitting descriptions shall be shown in a box with arrow to the fitting
or group of fittings. Text for proposed improvements shall not be smaller than
100 Leroy Template.
2.1. Plan View jC
sr('dd")Vat rr�
_ 3 7
Water Line3 7
bw� a
Water Valve (Gate) -- "- 3 7
Water Valve (Butterfly) - - 3 7
Tapping Sleeve and Valve Tsar. 3 7
t COL
F �re Hydrant _ sar _
� 3 7
Reducers __..fir 3 7
Round Connections 3 7
2.2. Profile View .WL_LD
Water Line � � 3 7
3 0
re M
TECHNICAL PEN UNE WEIGHT/
WT NUMBER WIDTH METRIC
0 0 0.014' .35mm LEGS
1 1 0.020' .50mm gi.I3(SIM
2 2 0.024' .60mm tC UNE CODE
3 3 0.031' .60mm
4 4 0.047' 1.20mm
6 6 0.055' 1.40mm
Page 9 of 12 Graphic Standards&Drawing
Requirements
GRAPHIC STANDARDS.—PROPOSED IMPROVEMENTS (Continued)
3. The following stondards are to be used for all proposed sanitary sewer line
improvements. Use line weight 3 for all proposed improvements.
All fitting descriptions shall be shown in a box with arrow to the fitting
or group of fittings. Text for proposed improvements shall not be smaller than
100 Leroy Template.
3.1. Plan View WT LC
24•(and amadsr)San. Saw. 3 3
Sanitary Sewer Lines 20'(and larger)San.Sal.
i a 3 3
Manhole Cr 3 0
3.2. Profile View WT LC
b 24'(and smiler)San.Saw. 8 3 3
Sanitary Sewer Lines 3 0
)- - - - ' - 9 3 3
]o'(ane laraar9 San.sw. - - - 4 3 0
Manhole _J L_
, 3 0
TECHNICAL PEN UNE WEIGHT/
WT NUMBER WIDTH METRIC
0 0 0.014" .35mm LEGEND
1 1 0.020" .50mm WT= UNE WEIGHT
2 2 0.024" .60mm LC= UNE(ODE
3 3 0.031" .80mm
4 4 0.047" 1.20mm
6 6 0.055" 1.40mm
Page 10 of 12 Graphic Standards&Drawing
Requirements
GRAPHIC STANDARDS—PROPOSED IMPROVEMENTS (Continued)
4. The following standards are to be used for all proposed storm sewer line
improvements. Use line weight 3 for all proposed improvements.
All fitting descriptions shall be shown in a box with arrow to the fitting
or group of fittings. Text for proposed improvements shall not be smaller
than 100 Leroy Template.
4.1. Plan View WT LL
24"(and emaMr)Sbn. Saw. 3 0
30"(end Larder)Sint Sw.
Storm Sewer Lines 6 d 3 0
Manhole o 3 0
"a" "a-r -c"
ri r"---1 3 0
Inlets \-No.a Pan-\ 1 [•7
[•7 11 I n 1 ID 3 0
"C--1" c-r "o-r
4.2. Profile View
Storm Sewer Lines }) 24"(and Snider)Sint. San. d 3 0
30"(and Lamer) abn Saw. 8 3 0
Manhole
r______I \________.3
3 0
Inlet
r 30
b______________
TECHNICAL PEN LINE WEIGHT/
WT NUMBER WIDTH METRIC
0 0 0.014" .35mm LEGEND
1 1 0.020" .50mm WI= LE wppR
2 2 0.024" .60mm LC= UNE CODE
3 3 0.031" .80mm
4 4 0.047" 1.20mm
6 6 0.055" 1.40mm
Page 11 of 12 Graphic Standards&Drawing
Requirements
GRAPHIC STANDARDS- PROPOSED IMPROVEMENTS (Continued)
5. The following standards ore to be used for all proposed pavement
improvements. Use line weight 3 for all proposed improvements.
All fitting descriptions shall be shown in a box with arrow to the fitting
or group of fittings. Text for proposed improvements shall not be smaller
than 100 Leroy Template.
5.1. Plan View WT LC
Face of Curb 6 3
Edge of pavement 6 0
Concrete Walk
T 3 3
Ir w 3 3
Concrete Header i I 3 3
Top of Curb or T.C.-7L55 GINL311 2 0
Gutter Elevation
5.2. Profile View
Top of Curb orr.c. qr
Center Line of _ • _t, 2 0 (TEXT)
Open Ditch Paving 3 3
TECHNICAL PEN UNE WEIGHT/
WT NUMBER WIDTH METRIC
0 0 0.014" .35mm LEGEND
1 1 0.020" .50mm W1= UNE WEIGH(
2 2 0.024" .60mm I. UNE CODE
3 3 0.031" .80mm
4 4 0.047" 1.20mm
6 6 0.055" 1.40mm
Page 12 of 12 Graphic Standards&Drawing
Requirements
CHAPTER 12
MISCELLANEOUS REQUIREMENTS
12.01 BARRICADES AND TRAFFIC CONTROL
A. It is the responsibility of the developer,contractor,or right-of-way user to maintain
traffic control devices in accordance with Texas Manual on Uniform Traffic
Control Devices (TMUTCD)on all construction projects.
B. Construction projects which have not been accepted by the City shall be barricaded
or otherwise closed to public use until acceptance by the City. It is the
responsibility of the contractor to provide and maintain barricades or other traffic
control devices in accordance with the TMUTCD, latest edition, and in a safe
manner.
12.02 APPROVED PRODUCTS LIST
A. The Engineering Department shall develop and maintain an Approved Products
List. All materials used in construction within right-of-ways and easements shall
be as specified on the City of Pearland Approved Products list. These documents
are available in the Engineering Department and are available for review upon
request.
12.03 CITY OF PEARLAND STANDARD CONSTRUCTION DETAILS
A. The Engineering Department shall develop and maintain Standard Construction
Details. These Standard Construction Details shall be maintained and updated
periodically by the Engineering Department. These documents are available in the
Engineering Department and are available for review upon request
END OF CHAPTER
Page 1 of 1 Miscellaneous Requirements