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R2000-117 10-09-00
RESOLUTION NO. R2000-117 A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF PEARLAND, TEXAS, ADOPTING STORM DRAINAGE DESIGN CRITERIA FOR DRAINAGE IMPROVEMENTS CONSTRUCTED WITHIN THE CITY AND ITS EXTRATERRITORIAL JURISDICTION. WHEREAS, the City of Pearland recognizes the need of uniform storm drainage design criteria to effectively mitigate storm water runoff; and WHEREAS, the City and Brazoria Drainage District No. 4 have cooperated to establish uniform storm drainage design criteria for the respective jurisdictions; now, therefore, BE IT RESOLVED BY THE CITY COUNCIL OF THE CITY OF PEARLAND, TEXAS: Section 1. That certain Storm Drainage Design Criteria Manual for drainage improvements constructed within the City and its extraterritorial jurisdiction, a copy of which is attached hereto as Exhibit A and made a part hereof for all purposes, is hereby authorized and approved. PASSED, APPROVED and ADOPTED this the 9 day of 0cl~ober , A.D., 2000. TOM REID MAYOR ATTEST: RESOLUTION NO. R2000-117 APPROVED AS TO FORM: DARRIN M. COKER CITY ATTORNEY 2 STORM DRAINAGE DESIGN CRITERIA FOIl THE CITY OF PEARLAND, TEXAS STORM DRAINAGE DESIGN REQUIRMENTS Prepared By: Revised By: .~r'.P.,,,.a~,o,,~& '.m co~Pa.~v LIA Engineering & Smwe.~ing, Inc. March 1999 September 2000 C~O of Pew-hmt~ Slorll Drol~la~yc De~'l~n Crlleria TABLE OF CONTENTS Section Page 1.0 INTRODUCTION .......................................................................................................... 1-1 1.1 DESCRIPTION ................................................................................ 1-1 1,2 BACKGROUND ................................................................................................ 1-1 1.3 PREVIOUS DESIGN REQUIREMENTS ......................................................... 1-I 2.0 DRAINAGE POLICY ................................................................................................... 2-1 2.1 DESIGN REQUIREMENTS ............................................................................ 2-1 ? ? STREET DRAINAGE '~ l 2.3 FLOOD CONTROL ........................................................................................... 2-I 2.4 RELATIONSHIP 'FO THE PERMITTING AND PLATTING PROCESS ........ 2-1 2.5 FINAL DRAINAGE PLAN AND PLAT ............................................................ 2-1 r 3.0 REFERENCES ............................................................................................................... 3-1 4.0 DEFINITIONS ............................................................................................................... 4-1 5.0 STORM SEWER AND ROAD-SIDE DITCH DESIGN REQUIREMENTS .......... 5-1 5.1 DETERMINATION OF RUNOFF ..................................................................... 5-1 5.1.1 Application of Runoff Calculation Models .............................................. 5-1 5.1.1.1 Acceptable Methodology for Areas Less than 200 Acres ........... 5-I 5. l.I .2 Acceptable Methodology for Areas Greater than 200 Acres ....... 5- l 5.1.2 Rainfall Durations for Hydrologic Modeling .......................................... 5-1 5.1.3 Application of the Rational Method ........................................................ 5-2 5.1.3.1 Calculation of Runoff Coefficient ............................................... 5-2 5.1.3.2 Determination of Time of Concentration ..................................... 5-3 5.1.3.3 Intensity-Duration Curves ............................................................ 5-3 5.1.3.4 Sample Calculation Forms .......................................................... 5-3 5.2 DESIGN OF STORM SEWERS ......................................................................... 5-7 5.2.1 Design Frequency .................................................................................... 5-7 5.2.t.1 Newly Developed Areas .............................................................. 5-7 5.2.1.2 Redevelopment or In-fill Development ....................................... 5-7 5.2.1.3 City of Pearland Projects ............................................................. 5-8 5.2.1.4 Private Drainage Systems ............................................................ 5-8 5.2.2 Velocity Considerations .......................................................................... 5-8 5.2.3 Pipe Sizes and Placement ......................................................................... 5-8 5.2.4 Starting Water Surface and Hydraulic Gradient ...................................... 5-9 5.2.5 Manhole Location .................................................................................... 5-9 5.2.6 Inlets ......................................................................................................... 5-9 5.2.7 Outfalls .................................................................................................. 5-10 5.3 CONSIDERATION OF OVERLAND FLOW .................................................. 5-I 1 5.3.1 Design Frequency ................................................................................ 5-1 l 5.3.2 P, elationship of Structures to Street ....................................................... 5-11 i SEPT-O0 CtO, of Pearhmd. 7'e.~ as Storm Drainage Des~,4n Crtterlq .thtlltttl[ IABLE OF CONTENTS (continued) Section Pag~ 5.3.3 Calculation of Flow. ............................................................................ 5-11 Ol tL..~N S ............................. '- 5.4 STORM WATER POLLUTION PREVENTI N r,, ~ > 11 5.5 DESIGN OF ROADSIDE DITCHES ............................................................... 5-12 5.5.1 Design Frequency ...............................................................5-12 5.5.2 Velocity Consideration ........................................................................ >- - 5.5.3 Culverts ............................................................................................... 5-13 5.5.4 Depth and Size Limitations for Roadside Ditches ......................... 5- 3 5.6 DESIGN OF OU['FALL PIPES ....................................................... 5-14 5.7 STORM WATER MITIGATION DETENTION ALTERNATIVES ............... 5-14 5.7. l Small Projects .................................................................................... 5-14 5.7.2 Medium Projects ................................................................................. 5-15 5.7.3 Large Projects ...................................................................................... 5-15 6.0 HYDROLOGIC ANALYSIS OVERVIEW ................................................................ 6-1 6.1 PEAK DISCttARGE DETERMINATION ......................................................... 6- l 6.2 SMALL WATERSHED METHOD HYDROGRAPtt METHODOLOGY ....... 6-1 6.2.1 Introduction ............................................................................................ 6-1 6.2.2 Equations ................................................................................................. 6-2 6.2.3 Applicauons ............................................................................................. 6-2 6.3 RAINFALL ......................................................................................................... 6-2 6.3.1 Rainfall Frequency and Duration ............................................................. 6-3 6.3.2 Rainfall Distribution ................................................................................ 6-3 6.3.3 Depth-Area Relationship ......................................................................... 6-5 6.3.4 Loss Rates .............................................................................................. 6-6 6.4 HYDROGRAPH METHODOLOGY ................................................................. 6-6 6.4.1 Watershed Parameters .............................................................................. 6-6 6.4.2 Drainage Area ......................................................................................... 6-7 6.4.~ Watershed Length .................................................................................... 6 6.4.4 Watershed Length to Centroid ................................................................. 6-8 6.4.5 Channel Slope .......................................................................................... 6-8 6.4.6 Watershed Slope ...................................................................................... 6-8 6.4.7 Percent Land Urbanization ......... '. ............................................................ 6-8 6.4.8 Percent Channel Improvement ................................................................ 6-9 6.4.9 Percent Channel Conveyance ................................................................ 6-9 6.4.10 Percent Ponding ..................................................................................... 6-10 6.5 HYDROGRAPII PARAMETERS .................................................................... 6-10 6.5.1 Unit Hsdrograph Parameters ................................................................. 6-10 6.5.2 Base Flows ............................................................................................. 6-11 ! ii SEPT-00 C~O. of Pearland, lYxas Storm Drainage Design Critema ~ [anual TABLE OF CONTENTS (continued) Section Page 6.6 FLOOD HYDROGRAPH ROUTING .. 6-12 6.6.1 Modified Puls Method .............................................. ..6-12 6.6.2 Procedure for Developing Storage-Outflow Using HEC-2 ................... 6-13 6.6.3 Routing Steps ......................................................................................... 6-14 6.7 USING ItEC-1 RESULTS IN HEC-2 .............................................................. 6-15 6.7.l Multiple HEC-1 Computation Points .................................................... 6-15. 6.7.2 Synthetic Discharge-Area Curve ........................................................... 6-15 7.0 HYDRAULIC CHANNEL DESIGN CRITERIA .......................................................7-1 7.1 INTRODUCTION ............................................................................................... 7-1 7.1.l Design Frequencies .................................................................................. 7-1 7.1.2 Required Analysis .................................................................................... 7-1 7. t.3 Acceptable Methodologies ....................................................................... 77~12 7.2 OPEN CHANNEL DESIGN ............................................................................... 7.2.1 Location and Alignment .......................................................................... 7-2 7.2.2 Existing Cross Sections ............................................................................ 7-2 7.2.3 Typical Design Section ............................................................................ 7-3 7.2.3.1 Earthen Channels ............................. .7-3 7.2.3.2 Concrete-Lined Trapezoidal Chmmels 7-5 7.2.3.3 Rectangular Concrete Pitot Channels .......................................... 7-6 7.2.4 Water-Surface Profiles ............................................................................. 7-8 7.2.4.1 General ......................................................................................... 7-8 7.2.4.2 Manning's Equation ..................................................................... 7-8 7.2.4.3 Manning's "n" Values .................................................................. 7-9 7.2.4.4 Velocities ........................................ 7.2.4.5 Flowline Slope ........................................................................... 7-10 7.2.4.6 Starting Water-Surface Elevations ............................................. 7-10 7.2.4.7 Headlosses .................................................................................. 7-10 7.2.5 Confluences ............................................................................................ 7-10 7.2.6 Transitions .............................................................................................. 7-1 1 7.2.6.1 Design ........................................................................................ 7-1 1 7.2.6.2 Analysis ...................................................................................... 7-1 1 7-12 7.2.7 Bends ...................................................................................................... 7-12 7.2.7.1 Design ........................................................................................ 7.2.7.2 Analysis ...................................................................................... 7-12 8.0 DETENTION SYSTEM DESIGN ................................................................................ 8-1 8.1 INTRODUCTION ............................................................................................... 8-1 8.1.1 Types of Storage Facilities ....................................................................... §-1 iii SEPT-00 C~ty of Pearland ?~,xas ,~lort~l Drainage Design Criterta Manual TABLE OF CONTENTS (continued) Section l'ag~ 8.1.2 Geotechnical Design ............................................................................. 8-2 8.2 DESIGN CONSIDERATIONS ........................................................................... 8-2 8.3 ON-SITE FACILITIES ....................................................................................... 8-3 8.3.1 Small Projects ......................................................................................... 8-3 8.3.2 Medium Projects ................................................................................... 8-3 8.3.3 Large Projects .......................................................................................... 8-5 8.4 OFF-SiTE FACILITIES ...................................................................................... 8-6 8.5 PUMP DETENTION SYSTEMS ............................................................ 8.6 STRUCTURAL AND GEOMETRIC PARAMETERS 8-8 8.6.1 General .................................................................................................... 8-8 8.6.2 Bottom Design for Natural And Permanent Pool Basin .......................... 8-8 8.6.3 Bottom Design ...................................................... for Manicured Ponds 8-9 8.6.4 Outlet Structure ........................................................................................ 8-9 8.6.5 Additional Design Considerations ......................................................... 8-10 8.6.5.1 Erosion Control .......................................................................... 8-10 8.6.5.2 Safety, Aesthetic Consideration and Multi-Purpose Use ........... 8-10 9.0 MISCELLANEOUS DESIGN CONSIDERATIONS ................................................. 9-1 9.1 STORM SEWER OUTFALLS ............................................................................ 9-1 9.2 GENERAL CONTROL STRUCTURES ............................................................ 9-l 9.3 STRAIGHT DROP SPILLWAY ......................................................................... 9-1 9.4 BAFFLE CHUTES .............................................................................................. 9-2 9.5 SLOPED DROP STRUCTURES ........................................................................ 9-2 9.6 UTILITY CROSSINGS ....................................................................................... 9-2 10.0 EASEMENTS AND RIGHTS-OF-WAY ................................................................... 10-1 11.0 SUBMITTAL ............................................................................................................... 11-1 11.1 PRELIMINARY SUBMITTAL .......................................... 11-1 11.2 FINAL DESIGN ................................................................................................ 11-1 11.3 SIGNATURE PAGE ......................................................................................... l 1-2 12.0 QUALITY ASSURANCE ........................................................................................... 12-1 13.0 DESIGN ANALYSIS ................................................................................................... 13-1 APPENDIX A DETENTION STORAGE VOLUME CALCULATIONS FOR SMALL AND MEI)IUM PROJECTS APPENDIX B EXHIBITS SEPT-00 Crt)' of Pearland, Teras Storm Dratnage Design Crtteria Mwutal TABLE OF CONTENTS (continued) LIST OF TABLES Table Page 6-1 Typical Point Rainfall Depth (Inches) Duration-Frequency Values ................................ 6-3 6-2 Typical 100-Year Frequency Point Rainfall Distribution ............................................... 6-4 6-3 24-Hour Design Rainfall Adjusted for Brazoria County ................................................. 6-5 6-4 100-Year Frequency Distribution Patterns for Northern Brazoria County. .................... 6-5 7-l Easement Criteria ............................................................................................................. 7-4 7-2 Manning's 'W' Values and Allowable 25-Year Velocities for Channel Design ............. 7-8 LIST OF FIGURES Figure Page 5-I Average Velocities for Estimating Travel Time for Overland Flow ............................... 5-4 5-2 City of Pearland IDF Curve ............................................................................................. 5-5 5-3 Storm Sewer Calculation Form ........................................................................................ 5-6 A-1 Precipitation Rainfall Depth-Duration-Frequency Curves Northern Brazoria County, Texas ................................................................................................ LIST OF EXHIBITS Exhibit 5-1 Storm Sewer Manhole, Type "C" for 42" Diameter RCP and Smaller 5-2 Storm Sewer Manhole, Type "C" for 48" to 72" RCP 5-3 Storm Sewer Manhole, Type "C" for 78" Diameter RCP and Greater 5-4 Storm Sewer Manhole for Proposed Concrete Box Sewer 5-5 Storm Sewer Junction Box with Lid for a Maximum 24" Diameter Storm Sewer Sewer Manhole Frame and Cover 5-6 Storm 5-7 Storm Sewer Grate Inlet 5-8 Storm Sewer Type "BB" Inlet Plate, Frame and I Beam 5-9 . Storm Sewer Ring Grate for Open to to end of 18" RCP Stubs Ditch 5-10 Storm Sewer Type "D" Inlet Grate and Frame 5-11 Storm Sewer Type 'D-I" Inlet Grate and Frame 5-12 Storm Sewer Type "A" Inlet Grate and Frame 5-13 Storm Sewer Type "C" and "H-2" Inlet Frame and Cover 5-14 Storm Sewer Bedding and Backfill 5-15 Storm Sewer Bedding and Backfill For RCP Where Unsatisfactory Soil Conditions Exist 5-16 Storm Sewer Type "A" Grate Inlet V SEPT-00 TABLE OF CONTENTS (continued) LIST OF EXHIBITS Exhibit 5-17 Storm Sev. cr l'.x pc "W' Inlet Rclncation 5-18 Storn~ Sc~c,' Type "[lB" Inlet 5-19 Storm Scx~cr'l>'pc"BB" lnlct Rclocanon 5-20 Storm Scv. cr'l'5pc "('" Inlet 5-21 Storm Sewer l'5pc "D" Inlet 5-22 Storm Sewer l'ype"D-l" Inlet >-_o Storm Se'~:cr l'}pc "E" Inlet 5-24 Storm Sewer Side Ditch Reception 5-25 Storm Scwcr Rcinforccd Monolithic Concrete 5-26 Storm Sc,act Reinforced Monolithic Concrete 5-27 Storm Sc~er Manhole Type "B" for 54" to 78" Monolithic Reinlbrccd £'oncrctc Scxxcrs 5-28 Storm Scv:cr Manhole Tspc "D" t'or Monolithic Reinforced Concrete Scx,,er 84" [)iamctcr and Greater 6-1 Comparison of ltydrologic Methodologies, Fully Dcvelopcd Watersheds 6-2 24-ttour. 100-Year l lyetograph in 30-Minute [ncrcmcnts 6-3 Average Watcrshcd Length (I.) vs - Drainage Area (llards Count5 6-4 Average l.ength to Centroid (L~ x) -rs - Drainage :",rca (l larr s CounU 6-5 Conveyance Discharge Slopes (S): 1 ['t/mile 6-6 Con,,eyancc l)~scharge Slopes (S) 3 ft/mile 6-7 Conveyance D~schargc Slope (S) = 5 ft/mile 6-8 Ponding Adiustment Factor 6-9 Discharge .,~rea Curves Ibr Storage Out[all Analyses 6-10 Precipitation Rainthll Depth-Duration-Frequency Curves Northern Brazoria Count5. Texas 7- I Bcrm Drain 7-2 Typical Roadsidc Ditch Interceptor Structure 7-3 Typical Secnon Concrete lrapczo~dal 7-4 Typical Weep ttole Dctail 7-5 '[ypical Structure Dctails ('oncrete [.ow Flow Section 7-6 Concrete l.ow Flow Section l'ypical Sections 7-7 Typical Channel Access Stairv.'ay for Concrete Lov, [:lov, Structures 7-8 Conflucncc Minmmm Requirement Chart 8-1 T.vp~cal Section Detention Basin Pilot Channel 9-I Typical Drax~ing. Outfall Pipe to Ditches with Paving 9-2 Typical Storm Sev, er Outfall Structure )-o Steel Sheet Piling Drop Structure 0-4 Typical Section - [Jtiht.'. Crossing vi ~t P I'-0(}