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Ord. 0058B 1970-05-25ORDINANCE NO. 58B AN ORDINANCE OF THE CITY OF PEARLAND, BRAZORIA, HARRIS COUNTIES, TEXAS, AMENDING ORDINANCE NO. 58 , ENTITLED SUBDIVISION REGULATIONS OF THE CITY OF PEARLAND, TEXAS, BY ADDING THERETO AND INSERTING THEREIN, FOLLOWING SECTIONS V-B-7, MINIMUM STANDARDS -SANITARY SEWERS AND V-B-8, MINIMUM STANDARDS -WATER LINES, NEW SUBSECTIONS TO BE HEREINAFTER REFERRED TO AS SUBSECTIONS 7 a-1 SECTION V-B AND 8 a SECTION V-B, AND REPEALING ALL ORDINANCES AND PROVISIONS OF ORDINANCES THAT CONFLICT HEREWITH. BE IT ORDAINED BY THE CITY COUNCIL OF THE CITY OF PEARLAND, TEXAS: SECTION I That Section V-B-7 and Section V-B-8 of Ordinance No. 58 , entitled SUBDIVISION REGULATIONS of the City of Pearland, Texas be and the same are hereby amended by adding thereto and inserting therein, following sections V-B-7 and V-B-8, the following new subsections to be known as 7 a-1 and 8 a and to read as follows: 7. Sanitary Sewers a. (1.) Where the subdivider and/or Developer, at his option, elects to extend the sanitary sewer service line from the main line to the property line, then and in that event, the subdivider and/or Developer shall be entitled to receive compensation for such sanitary sewer service line installation in the amount of THIRTY AND NO/100 ($30.00) DOLLARS. Said Compensation to be paid by the City at such time as the property owner applies and pays for the Sanitary Sewer tap fee as prescribed by the City Council. 8. Water Lines: a. Where the subdivider and/or developer, at his option, elects to extend the water supply line from the main line to the property line, then and in that event, the subdivider and/or developer shall be entitled to receive compensation for such water supply line service installation in the amount of SIXTY AND NO/100 ($60.00) DOLLARS. Said Compensation to be paid by the City at such time as the property owner applies and pays for the Water supply tap fee as prescribed by the City Council. -1- SECTION II All ordinances and provisions of ordinances in conflict with amendments heretofore made are hereby expressly repealed to the extent of such conflict. PASSED AND APPROVED at a regular meeting of the City Council of the City of Pearland, at which meeting a quorum was present, on the first and final reading, the g r day of , 1970. ATTEST: A ity Secretar, MAYOR, C t'rof Peaand -2- G a ,E rrB1-T -B' CITY OF PEARLAND SPECIFICATIONS FOR THE DESIGN AND CONSTRUCTION OF STORM SEWERS CHAPTER 1 - DESIGN STANDARDS 1.1 GENERAL: The design of storm drainage improvements in the City of Pearland shall be based on one of the following methods: a) For areas of 1000 acres or less: The design for areas less than 1,000 acres shall be based on the Rational Formula. The formula for calculating storm flows in this manner is Q = CIA, where Q is the storm flow in cubic feet per second at a given point of design. C is a runoff coefficient which is the ratio of the maximum rate of runoff to the average rate of rainfall. 1 is the average intensity of rainfall- in inches per hour for the calculated time of concentration at the design point. A is the drainage area in acres at the design point. b) For areas of more than 1000 acres: The unit hydrograph method shall be used in determining the design runoff for watersheds greater than 1,000 acres. The unit hydrographs may be determined by use of the Corps of Engineers computer program HEC-1 with analysis of the channelsto be completed using the Corps of Engineers HEC-2 program. Copies of all computer runs shall be submitted to the City of Pearland for review. Background information may be taken from a Corps of Engineers' report on any major channel for which a report has been published. A map (2 copies) of the total area involved showing individual drainage areas for each inlet, ditch, or point of design shall be submitted with the preliminary plat or design. The area in acres and volume of flow in CFS shall be indicated at each point of design. Calculations showing per cent runoff, time of concentra- tion, rainfall intensity, etc. shall be submitted for the approval of the City Engineer. 1.2 QUANTITY OF STORM WATER: The quantity of storm water runoff shall be determined for each inlet, bridge, culvert, or other designated design point by using the following standards as applicable to the above requirements: 1.2.1 Runoff Coefficient: The runoff coefficient shall be determined for each drainage area from the runoff coefficients for land use: a) Commercial areas and General Business 0.95 b) Neighborhood Service, Office and Professional and Multi -family areas 0.90 c) Industrial areas M1 and M2 0.85 d) Residential areas 1) Lots <_ 1.0 acre 0.55 2) Lots > 1.0 acre 0.40 e) Park areas 0.30 Composite runoff coefficients will be determined by direct proportion when more than one land use exists within a drainage area, i.e. Planned Unit Development, Plan Approval. -1- 1.2.2 Rainfall Intensity: Rainfall Intensity - Duration - Frequency curves have been developed for 3, 25, 50 and 100 year frequency storms from data contained in Attached Figure 1. These curves as presented in Figure 1 have been determined for durations of 10 minutes to 24 hours. The intensity, 1, in the Rational Formula shall be determined from the time of• concentration and design storm frequency. a) Time of Concentration: The time of concentration shall be calculated for all inlets and pipe junctions in a proposed storm sewer system or other points of analysis. The time of concentration shall consist of inlet time and time offlow in the sewer and plus a 10 minute initial concentration time. For drainage areas of one acre or less the time of concentration need not be calculated and a storm duration of 10 minutes may be used as the basis of design. . b) Storm Frequency: Storm frequencies for the storm drainage improvements in the .City of Pearland are as follows: Design Storm Frequency Type of Facility Road Side Ditches & Road Side Culverts Storm Sewers Culverts, Bridges and Channels Creeks Design Frequency (Years) 3 3 100 100 yrs. yrs. yrs. yrs. 1.2.3. Area:. The area used in determining flows shall be calculated by subdividing a map into drainage areas within the basin contributing storm water runoff to the system. 1.3 STORM DRAINAGE DESIGN: Before the construction or reconstruction of any street and before the construction of any building or other structure on a site of three or more acres, an engineering investigation shall be made to determine the necessity of on -site or off -site storm drainage facilities to meet the require- ments of this ordinance. 1.3.1 Surface Drainage on Streets: Storm drainage inlets shall be located and designed so as to limit the depth of water at the face of curb on any Class A street to five inches base on a 5-year frequency storm. 1.3.2 Surface Drainage on Private Property: 0n lots or tracts of three acres or more or on all lots zoned other than single-family residential, storm water runoff shall not be permitted to drain onto adjacent property or streets except in existing creeks, channels, or storm sewers provided easements for the creek, channel, or storm sewer have been dedicated to the City of Pearland. -2- 1.3.3 Storm Sewers: Storm water runoff in excess of that permitted to be carried on the surface shall be collected and transported in a storm sewer system. Such storm sewer systems shall be designed using Manning's equation for pipe and channel capacity: Q = 1.486 n A R 2/3 S 1/2 where Q = Discharge in cubic feet per second n = Coefficient of roughness A = Cross -sectional area of flow in square feet R = Hydraulic Radius in feet S = Slope of hydraulic gradient in feet per foot The coefficient of roughness shall be determined as follows: Sewer Type N Concrete Pipe Corrugated Metal Pipe Concrete Lines Channel Earth Channel 0.013 0.021 0.015 0.045 Storm sewer pipes shall be designed so that the average velocity of flow shall be not less than three (3) feet per second and not more than fifteen (15) feet per second. The outfall shall in all cases be properly protected. The minimum size of storm sewers placed in public right-of-way shall be eighteen (18) inches. in diameter or equivalent cross -sectional area. Storm sewers used to drain private property shall be no less than eight (8) inches in diameter. The connection between the private system and the public system shall be no less than fifteen (15) inches in diameter. 1.3.4 Open Channels: When the calculated pipe size for a storm sewer system exceeds seventy-two (72) inches in diameter, storm water runoff may be transported in open channels. Open channels may be fully lined, partially lined or unlined. All unlined or partially. lined .channels shall be bordered by an open space on both sides of the channel a minimum width of twenty-five (25) feet. Maximum earth slopes for unlined or partially lined channels shall not exceed 2:1. Partially lined channels shall consist of a concrete paved bottom and either earth slopes or concrete lined slopes to a height not less than one foot above the design depth of water. Fully lined channels shall consist of concrete lined bottom and slopes extending at least one foot above the height of design water depth. Maximum side slopes for fully lined channels shall be 1:1. 1.3.5 Bridges and Culverts: In addition to satisfying capacity requirements resulting from the application of Manning's formula, bridges constructed to provide crossings of streams and open channels shall have a clear height of one foot above the calculated upstream water depth for the design storm. The side .slopes of the channel underneath the bridge shall be protected with concrete riprap. Culverts shall be designed using the Texas Highway Department design criteria. Culverts shall have upstream and downstream slope protection in the form of headwalls or wing walls. 1.3..6 Hydraulic Gradient: In storm drainage systems flowing full, all losses of energy through resistance of flow in pipes must be accounted for by the accumulative head losses along the system. These calculations determine the hydraulic grade line along the storm drain system or the water surface elevation which will exist at each structure. The hydraulic grade line shall be established for all drainage systems. In open channels, the water surface itself is the hydraulic grade line. Calculation of the hydraulic grade line must be related to the downstream water elevation for the particular design storm. For the three year design storm the hydraulic grade line in a storm sewer system shall remain below the gutter elevation of the street. For open channels the hydraulic grade line shall be one (1) foot below the lowest top of bank. Allowances must be made for future extensions of the storm drainage system. At each point of discharge into a channel, the hydraulic grade line of the channel shall be determined for the 100-year design storm. The hydraulic grade line shall not be raised more than 6 inches due to the increased flow caused by the proposed improvements; provided that the water levels do not exceed the bank of the channel if the original level was confined in the banks or does not cause damage to downstream property. -4- CHAPTER II - CONSTRUCTION STANDARDS 2.1 CONCRETE STRUCTURES: 2.1.1 Description: This item shall consist of the construction of concrete structures and other incidental work. 211.2 Materials and Methods: All concrete construction shall conform to the provisions of the "Building Code Requirements for Reinforced Concrete" (ACI 318-63) of the American Concrete Institute. 2.1.2.1 Portland Cement: Portland Cement shall conform to "Specifications for Portland Cement" ASTM Designation C 150, Type I, II or III. 2.1.2.2 Fine Aggregate: Fine aggregate shall consist of sand or a combination of sand and not more than fifty (50) percent of stone screenings. Sand shall be composed of clean, hard, durable uncoated grains. Stone screenings shall consist of clean hard durable uncoated fragments resulting from the crushing of stone. The maximum amount of deleterious substances shall not exceed the following percentages by weight: Material removed by decantation (A.S.T.M C-117) 3% Clay lumps 0.5% Other deleterious substances such as coal, shale, coated grains and soft flaky particles 2.0% The aggregates shall be free from an excess of salt or alkali. When tested by approved methods, the fine aggregates shall conform to the following grading requirements: Retained on 3/8" Screen 0% Retained on 1/4" Screen 0 to 5% Retained on 20 mesh Sieve 15 to 50% Retained on 100 mesh Sieve 85 to 100% Aggregates, in addition to these specifications, shall meet the requirements of A.S.T.M. C-33• 2.1.2.3 CoarseAggregate: Coarse aggregate shall consist of gravel, or crushed stone, washed and graded. The aggregate shall be clean, hard and durable, free from any long splintery pieces and free from dirt, dust, vegetable or organic matter, or other objectionable materials, either free or as a coherent agent. Stone and gravel shall be reasonable uniform and durable in quality and have a wear of not more than forty (40) percent. The maximum permissable percentages of deleterious substances shall not exceed thefollowing percentages by weight: Material removed by decantation (A.S.T.M. C-117) 1.0% Shale, slate or other similar materials 1.0% Clay lumps 0.25% Soft Fragments 3.0% Other deleterious substances including friable, thin, elongated, orlaminated pieces 3.0% The sum of all deleterious ingredients, exclusive of material removed by decantation, shall not exceed 5% by weight. -5- a The aggregate shall be free from an excess of salt, alkali, vegetable matter, or other objectionable materials either free or as adherent coatings. When tested by approved methods, the coarse aggregate shall conform to the following grading requirements: Retained on 1-1/2" Screen 0 to 5% Retained on 3/4" Screen 25 to 60% Retained on 1/4" Screen 95 to 100% Aggregates in addition to these specifications,shall meet the requirements of A.S.T.M. C-33 . 2.1.2.4 Water for Concrete: Water used in mixing concrete shall be clean and free from injurious amounts of oils, acids, alkalis, organic materials or other deleterious substances. 2.1.2.5 Proportions: Concrete shall be proportioned as determined by an approved commercial testing laboratory by absolute volumes and in accordance with the requirements hereinafter set forth. Copies of the design shall be submitted to the City prior to placing any concrete. For placements of concrete involving twenty-five (25) cubic yards or less on one continuous placement, the require- ments for absolute batch design may be waived, and a mix proportion may be determined by trial mixes; however, the requirements for weighing and measuring materials will not be waived. The concrete shall be uniform and workable. The compressive strength of concrete desired, minimum cement content and maximum allowable water content shall conform to the following: Compressive Compressive. Minimum Maximum Maximum Strength Strength Cement Content Water Content Slump 7 days psi 28 days psi Bags per Cu. Yd. Gals. per Bag Inches 1400 2000 4.5 7.50 1700 2500 5.0 7.00 2000 3000 6.0 6.25 3 3 6 An air entraining agent may be used in the concrete. The agent used shall be one of those permitted under Specifications for "Air -Entraining Admixtures for Concrete," ASTM Designation C-260. 2.1.2.6 Mixing of Concrete: .The concrete shall be mixed in quantities required for immediate use, and concrete whichisnot in place within thirty (30) minutes after being discharged from the mixer will not be used. Retempering of concrete will not be permitted. The mixing shall be done in .a batch mixer of approved type and size which will ensure the uniform distribution of material throughout the mass so that the mixture will be uniform in color and smooth in appearance. Concrete improperly mixed shall not be used in the work. 2.1.2.7 Ready Mix Concrete: The use of ready -mix concrete shall conform to ASTM Specifi- cations C-94. The quality of materials and desired compressive strength shall be as above. Care shall be taken that the over -mixing of materials in a delayed truck does not damage the entire batch. The maximum period from the time water is added and the mixing begins until the concrete is delivered into forms shall in no case exceed oneand one-half (1-1/2) hours. Whenever segregation or partial setting raises a question as to the quality of the concrete, it shall not be put into the forms. • 2:1:2.8 Mortar: Mortar used for joints, plastering and where called for in the plans and specifications shall consist of one part cement to two parts sand meeting the requirements for cement and fine aggregate as set out above. 2.1.2.9 Form Work: Forms shall be built mortar -tight and of material of sufficient strength to prevent bulging between supports and shall be set and maintained to the lines designated until the concrete is sufficiently hardened to permit form removal. Forms shall be maintained in such a manner to eliminate shrinking or warping during the elapsed time between their construction and the placing of concrete. All form construction shall be inspected by the Engineer and no concrete shall be placed until the Engineer has seen the forms. Forms shall be capable of withstanding the pressure exerted by a liquid weighing one hundred and fifty (150) pounds per cubic foot and an additional live load of fifty (50) pounds per. square foot on horizontal surfaces. If, at any stage of the work, the.forms show signs of bulging or sagging, that portion of the concrete causing such condition shall be immediately removed if necessary, and the forms shall be reset and securely braced against future movements. Lumber for forms shall be properly seasoned and of good quality. free from loose or which would affect unsound knots, twists, shakes, decay and other It shall_ be imperfections concrete. The lumber used for facing or sheathing shall be surfaced on all sides and shall be sized to uniform thickness. Nominal one (1) inch thickness lumber will be permitted for general use if backed by a sufficient number of studs and wales. Forms for exposed exterior surfaces and for inside walls shall be lined with clean, smooth plywood, masonite its strength or impair the finished surface of or other equal material. Form lumber to be reused shall be maintained clean accuracy, shape,. strength, rigidity, tightness and defectivelumber shall not be reused. Studs shall not be less than two (2) inches by four (4) inches nominal section and shall be spaced. center to center not more than twenty (20) times the actual thickness of the facing lumber. Where practical, studs shall be capped at the top with a plate of not less than two (2) inches by six (6) inches nominal size, carefully selected as to straightness. All joints in plates shall be scabbed at least four (4) feet each way to provide continuity. Walesshallbe spaced at such intervals as to hold forms securely to the designated lines. All wales shallbe scabbed at least four (4) feet on each side of joints to provide continuity. A row of wales shall be placed within six (6) inches of the bottom of each placement. the and in good condition as to smoothness of surface. Any Forms for walls or columns shall not be erected on concrete footings until the concrete in the footing has cured at least two curing days. Forms shall be rigidly braced to prevent movement while concrete is being placed. All face form materials shall be fastened to allstudsand shall have true horizontal and vertical. joints. Facing material on horizontal and other surfaces shall be placed with parallel and square joints. -7- Metal form ties of an approved type shall be used to hold forms in place. Such ties shall be of a typeespecially designed for use in connection for concrete, and they shall have provision to permit ease of removal of the metal as hereinafter specified. The use of wire form ties will not be permitted except for minor or special form areas where the use of rigid type metal ties would be impracticable. Ties shall be held in place by devices attached to wales. Each device shall be capable of developing the strength of the tie. All metal appliances used inside of forms to hold them .in correct alignment shall be removed to a depth of at least one-half (1/2) inch from the surface of the concrete without undue injury to the surface by chipping or spalling. Such devices when removed shall leave a smooth opening in the concrete surfaces. Burning off of rods., bolts or ties will not be permitted. Where wire ties are used, all wires, uponremoval of the 'forms shall be cut back at least one-half (1/2) .inch from the face of -the concrete with a sharp chisel or nippers. All cavities produced by the removal of metal ties shall be carefully cleaned and completely filled with re -tempered sand -cement mortar mixed in proportion of one to three, and the concrete shall be left smooth and even. At the time of placing concrete, the forms shall: be clean and entirely free from all chips, dirt, sawdust and other extraneous matter. The facing of all forms shall be treated with oil before the reinforcement or concrete is placed. The oil used for this purpose shall be a light, clear oil which will not discolor or otherwise injuriously affect the concrete surface. In general, all forms shall be thoroughly wetted before the concrete is placed. The above specifications as regards design, mortar -tightness, bracing, alignment, removal, re -use, oiling and wetting shall apply equally to metal forms. The metal used for forms shall be of such thickness that the forms will remain true to shape. All bolts and rivet heads on the facing sides shall be counter- sunk. Clamps, pins or other connecting devices shall be capable of holding the forms rigidly together and allowing their removal without injury to the concrete. Metal forms which do not present a smooth surface will not be used. 2.1.2.10 Placing of Concrete: Concrete to be used shall be as specified herein or as specified on the plans and shall be .placed in the following manner: The operation of depositing and compacting the concrete shall be conducted so as to form a compact, dense, impervious mass of uniform texture which shall show smooth faces on all surfaces. The method and manner of placing shall be such as to avoid .the possibility of segregation or separation of the aggregate or the displacement of reinforcement. Where possible, concrete shall not have a free fall of more than four (4) feet. All concrete shall be well compacted and the mortar flushed to the surface of the forms by continuous working with concrete spading implements or mechanical vibrators, thoroughly working the concrete around the reinforcement, embedded fixtures, and into the corners and angles of the forms. Vibration shall not be done to the extent that will cause segregation. -8- No concrete shall be placed when the atmospheric temperature is below 40° F without the approval of the Engineer. It is understood that the Contractor is responsible for the placing of concrete under any and all weather conditions. 2.1.2.11 Finish: Where surface finish is required it shall be done in accordance with•. the following provisions: As soon as the forms are removed and all necessary painting has been done, the surface requiring finish shall be rubbedsufficiently to bring the surface to a paste, to remove all form marks and projections and to produce a smooth dense surface without pits or irregularities. Unless otherwise specified, all exposed corners are to be chamfered. 2.1.3 Design and Testing: The concrete mix will be designed by the approved testing laboratory with the intention of producing a concrete of the desired strength in 28 days.. This strength shall be checked during construction by taking a minimum of two (2) test cylinders during each pour or a minimum of two (2) test cylinders during each twenty-five (25) cubic yards of continuous pouring. A compressive test at seven days, and one test at 28 days. These tests shall_. be conducted by an approved testing laboratory and the cost of these tests is to be borne by the Contractor. The. desired minimum strengths shall be as follows: All structures including manholes and inlets 3000 psi Lining for channels 2000 psi 2 1 4 Reinforcing Steel: Reinforcing steel shall be deformed bars meeting ASTM Spec. A-615 for Open hearth, Grades 40,.60 or 75, New Billet Bars. Bars shall be free from flaws, cracks or other defects of railing, shall be true to size and shape and shall be free of loose scales and rust. A thin coat of firmly attached rust shall not be cause for rejection. Bars shall be free from heavy dirt, grease, paint, oil or other destroyers of bond. They shall be prefabricated to detail and delivered on the job plainly tagged and ready to set. Shop drawings in detail and in quadruplicate shall be submitted to the Engineer for approval before fabrication. Welded wire fabric, reinforcement shall be cold.drawn from rods hot rolled from Open Hearth Billets and shall conform tothe requirements of ASTM Specifications A-82. Steel or wire reinforcement shall be placed in the exact position shown on the plans and held securely in place at the proper spacing by means of approved metal spacers or approved pre -cast mortar or concrete blocks. Unless provision for welding is made, all reinforcing steel shall be wired together at all inter- sections. Splices shall have a lapped length of not less than thirty (30) times the diameter of the reinforcement. Laps shall be located at points of low tensile stress. Bars shall be rigidly clamped or wired at all splices in a manner approved by the Engineer. Sheets. of wire mesh shall be overlapped sufficiently to maintain a uniform strength (at least one full mesh) and shall be securely fastened at the ends and edges. No concrete shall be deposited until the Engineer has inspected the placing of reinforcement and given permission to place concrete. -9- 2.1.5 Structural Excavation 2.1.5.1 Description: These specifications shal?•govern the excavation for the placing of structures; for the disposal of all material obtained from such excavation; and for the backfilling around completed structures to the level of the original ground or to the grade shown on plans. The work to be done shall include all necessary pumping or bailing, sheeting, drainage, and the construction and removal of any required cofferdams. 2.1.5.2 Construction Methods: Excavation shall be done in accordance with the lines and depths indicated on the plans or as established by the Engineer. Unless written permission to the contrary is given by the Engineer, no excavation shall be made outside a. vertical plane three feet from the footing lines and parallel thereto. When cassions are provided, no excavation will be permitted outside the outer faces of the caissons. In order that the Engineer may judge the adequacy of a proposed foundation, the Contractor, if requested, shall make soundings to determine the character of the subgrade materials. The maximum depth of such soundings will not be required to exceed 5 feet below the proposed footing grade. It is the intent of this pro- vision that soundings shall be made at the time the excavation in each foundation. is approximately complete. 2.1.5.3 The final elevation to which a'foundation is to be constructed shall be as shown on the plans or as raised: or lowered by written order of the Engineer when such alterations are judged proper to satisfactorily comply with the design .requirements for the structure. Should it be found necessary, in the judgment of the Engineer, to increase or decrease the depth of footings from that shown on the plans, the necessary alterations in the details of the -structure shall be accomplished in a manner as directed by the .Engineer. 'Special care shall be taken not to disturb the bottom'of the excavation. The' final removal of the foundation material to grade shall not be performed until just before the f-oting is to be placed. Excavated material required to be used for backfill may be deposited by the Contractor in storage piles at points convenient for rehandling of the material. during the backfilling operations. Excavated material required to be wasted shall be disposed of by the Contractor, and the disposal shall be in such manner as not to obstruct drainage or otherwise impair the efficiency or appearance of the structure or other part of the work. Cofferdams: The term "Cofferdam," wherever used in this specification, designates any .temporary or removable structure which is constructed to hold the surrounding earth, water, or both, out of the excavation, whether such structure is formed of earth,. -timber, steel, concrete, or a combination of these. It thus includes earthen dikes, timber cribs, any type of sheet piling, removable steel shells and the like, and all necessarybracing; and it shall be understood also to include the use of pumping wells or well points for the same purpose. -10- It is the intent of this specification to require that a suitable cofferdam be provided for all excavations where such cofferdams may be necessary in order to control water conditions or to preclude sliding and caving of the walls of the excavation. Where no ground or surface water is encountered, the cofferdam need be sufficient only to protect the workmen and to avoid caveins or slides extending beyond the excavation limits. In general, sheet piling cofferdams shall extend well below the bottom of the footings and shall be well braced and as water -tight as practicable. When foundation piling are to be driven inside a caisson or cofferdam before placing a concrete seal, the excavation may be extended below the footing grade to a depth sufficient to allow for operations. After the piling have has risen_ to a .level more than one swell of the material during pile driving been driven, all foundation material that foot above the footing grade shall be removed. It is the intention of this provision to establish a construction tolerance to be applied when a foundation is being constructed under water. Where it is possible to unwater the caisson or cofferdam before a seal is placed, it is considered• practicable to remove the foundation material to exact footing grades after foundation piling are driven. Backfilling in a foundation to. compensate for excavation which has been extended below grade will not be permitted. Such areas below grade shall be filled with concrete at the time the seal or base courses are placed, and the concrete qualitiesinvolved shall be at the Contractor's expense. Cofferdams which tilt or move laterally during the process of sinking shall be righted or enlarged as necessary, at the sole expense of the Contractor. Unless otherwise provided, cofferdams shall be removed by the Contractor after the completion of the substructure. The removalshall be effected in such a manner as not to disturb or mar the structure. 2.1.6 Pumping or Bailing: Pumping or bailing from the interior of any foundation enclosure shallbe done in such manner as to preclude possibility of the movement of water through or alongside any concrete being placed: No pumping or bailing willbepermitted during the placing of concrete or for a period of at least 24 hours thereafter,unless it is done from a suitable sump separated from the concrete work by a water -tight wall. Pumping or bailing to unwater a sealed cofferdam or caisson shall not be started until the seal has set at least 36 hours. 2.1.7 Backfilling: As soon as practicable, all spaces excavated under this specification and not occupied by the permanent structure be placed in layers not more than 12 inches satisfactorily to the level of the original shown on plans. The material shall be free or other extraneous material. shall be back -filled. Backfill shall in depth and shall be compacted surrounding surfaces or to elevations from large or forzen lumps, wood, If the excavation has been made through a hard material resistant to erosion, the backfill around piers and in front of abutments and wings may be ordered by the Engineer to be of stone or lean concrete, in which .case, and unless otherwise provided, such backfill shall be paid for as extra work. -11- • No backfill shall be placed against any abutment or. retaining wall until such structure has been in place at least 10 days. Backfill placed around special manhole, retaining walls and piers shall be deposited on both sides to approximately the same elevation at the same time. Care shall be taken to prevent any wedging action of backfill against the structure, and the slopes bounding the excavation shall be stepped or serrated to prevent such wedge action. No backfilling shall be done except in the presence of the Engineer or his authorized representative. Each layer of the backfill shall be compacted to 95% Standard Proctor Density in accordance with AASHO T-99. An approved commercial testing laboratory shall obtain one density test per layer of fill. The cost of testing shall be borne by the Contractor. A copy of all test results shall be submitted to the Engineer. 2.1.8 Construction Joints: Construction joints shall be placed at the locations shown on the plans,"and concrete shall be poured in one continuous operation between such construction joints; however, where work is unavoidably suspended between regularly planned construction joint locations before the concrete shall have taken its initial set, then a construction -joint located and formed in a manner satisfactory to the Engineer shall be placed.- Keys ofthe depth and width shown on the plans shall be formed by imbedding water soaked wooden strips in the soft concrete and removing them after the concrete has hardened. .When keys for joints not shown on the plans are required, they shall not be leveled off, but shall be left somewhat 'rough. Forms which have spread away from the concrete already in place.shall be drawn back tightly against the concrete before placing fresh concrete. Upon resuming concreting, the surface of the concrete previously placed shall be thoroughly cleaned of all dirt, - scum, laitance or other inert materials, using a stiff wire brush,• or by other .means approved by -the Engineer. Immediately preceding the placing of fresh concrete, the surface of the concrete previously placed shall .be thoroughly washed with clean water and covered with a substantial coating of cement mortar of the same mixture used in. -the concrete. All measures necessary shall be taken by the Contractor tosecure a good bond in the concrete at -construction joints. 2.1.9 Removal of Forms: Forms shall not be removed within three (3) days of the place- ment of the concrete, and such removal shall be carried out in a manner to ensure the complete safety of the structure. In gen ral, forms for the several classes of work listed herein below shall remain in p ace, after the concrete has been placed, until the concrete has attained the fallowing compressive strength in pounds per square inch: Bottom Forms of Concrete SI.bs 1,200 lbs. Side Forms of Wall, Beams & Girders 800 lbs. The Contractor shall be responsible for all damage caused by the removal of forms. -12- 2.1.10. Curing Concrete: Careful attention shall be given to the proper curing of all concrete. The Contractor shall inform the Engineer fully as to the methods and procedures proposed for curing; shall provide the proper equip- ment and material in adequate amounts; and shall have approval of the methods,. equipment and material proposed prior to placing concrete. Inadequate curing facilities or lack of attention to the proper curing of concrete, shall be cause for the Engineer to stop all construction on the job, until approved curing is provided. All concrete shall be cured for a period of four (4) curing days. A curing day is defined as a calendar day on which thetemperature, taken in the shade away from artificial heat is above 50° F for at least 19 hours. The following methods are permitted for curing concrete: 1. Form Curing 2. Water Curing: (a) Wet material; (b) Water spray; (c) Ponding 3. Membrane Curing 2.2 REINFORCED CONCRETE PIPE: 2.2.1 Description: .These specifications shall govern for the furnishing and placing of reinforced concrete pipe. The pipe shall be installed in accordance with the requirements of these specifications, to the, line and grades shown on the plans, and shall be of the classes, sizes, and dimensions shown thereon. The -installation of pipe shall include all joints or connections to new or existing pipes,. manholes, catch basins, headwalls, etc., as may be required to complete the work. 2.2.2 Materials: Materials, manufacture, and design of pipes shall be as prescribed in the current standard specifications for "Reinforced Concrete Culvert, Storm Drain and Sewer Pipe." ASTM Designation C-76-57T and in the additional provi- sions contained herein. All pipe shall be machine made and shall be Class III or as designated on the plans. Pipe shall be substantially free from fractures, large or deep cracks,lamina- tions, and surface roughness. The planes of the ends of the pipe shall be perpendicular to the longitudinal axis. The ends of the pipe shall be of such design that when laid, the pipe sections will form a continuous conduit with a smooth and uniform interior surface. The following shall be clearly stencilled on the pipe: a. The pipe class. b. •The date of manufacture. c. The name or trade -mark of the manufacturer. d. Elliptical pipe with circular reinforcing and circular pipe with elliptical' reinforcing shall have the word "top" or "bottom" placed on the inside of the pipe at the correct place to indicate the proper position when laid. e. Inspector's identification mark. -13- The pipe shall be subject to rejection because of failure to meet any of the specification requirements or any of the following conditions: 1. Fractures or cracks passing through the shell, except that a single end crack that does not exceed the depth of the joint shall not be cause for rejection. If a single end crack that does not exceed the depth of the joint exists in more than 10% of the pipe, however, the defective pipe shall be rejected. 2. Defects which indicate imperfect placing, mixing, and curing of the concrete. 3. Spalls deeper than one-half the depth of the joint or ex- tending more than 4" around the circumference. If spalls not deeper than one-half the depth of the joint or extending not more than 4" around the circumference exist in more than 10% of the pipe, however, the defective pipe' shall be rejected. 4.- Exposure of the reinforcement when such exposure would indicate that the reinforcement is misplaced. 5.. The complete absence of distinct web -like markings, which is indicative of a.possible deficiency of water in the concrete mix, from the external surface of the pipe made by any process in which the forms are removed immediately after the concrete has been placed. All rejected pipes shall be plainly marked by the Engineer and shall be replaced by the Contractor with pipes which meet the requirements of these specifications. Such rejected pipes .shall be immediately removed from the site of the work. 2.2.3 Trench Excavation 2.2.3.1. Sewer Trenches: Except as otherwise. specified or shown on the plans, all sewers - shall be constructed in open cut trenches with vertical sides. Trenches for pipe sewers smaller than 30-inch pipe shall have a -width below the top of the pipe bell or other joint of not less than the outside diameter of the pipe plus 12 inches and not more than the outside diameter of the pipe plus 18 inches. Trenches for pipe sewers 30 inches and larger shall have a width below the top of the pipe of not less than the outside diameter of the. pipe plus 16 inches and shall be wide enough to permit making up the joints but shall not be wider than the outside diameterof the pipe plus 24 inches. Above the tops of pipe bells, the width of the trenches may be greater than the limits specified above by an amount sufficient only to permit placing sheathing and bracing timbers and to permit installation of well point headers or manifolds and pumps in the trench -where- the depth of trench is such as to make it uneconomical to pump from surface installation. Sufficient space must be provided between cross braces to permit handling of forms, pipe and other materials. -i4- No excavated material shall be deposited on the gravel, shell, asphalt, concrete or other paved area of any roadway or sidewalk, or on any lawn, garden or shrubbery,. and such material shall be handled in such a manner as not to obstruct drainage. Where necessary for compliance with this provision, the material shall be hauled. 2.2.3.2 Dewatering Trench: No sewer pipe shall be laid in a trench in the presence of water. All water shall be removed from trench sufficiently ahead of the sewer placing operation to ensure a dry, firm bed on which to place the sewer, and trench will continue to be dewatered until after all concrete and mortar is set. Removal of..water.may be accomplished by bailing, pumping, or pumping in connection with wellpoint installation as the particular situation may warrant. 2.2 3.3 Sheeting and Bracing: Where necessary in the Engineer's opinion, the sides of the trench or other excavation shall be braced and rendered secure to the satisfaction of the Engineer. In sewer trenches and other excavations having vertical sides, sheeting and bracing necessary to support the sides of the excavation in a vertical plane shall be installed. In trenches for monolithic sewers, flooring shall be installed as bracing to support the bottom of the vertical sheeting. Flooring shall be set solidly against undisturbed earth in the bottom of the trench. Where voids are left below the flooring the boards shall be spacedapproximately two inches apart to permit the concrete to flow between the boards to fill the voids. In no case shall loose earth be permitted to remain beneath the flooring. After the excavation has been backfilled and water tamped, steel or other sheeting may be pulled,_ otherwise sheeting and bracing, once installed may not be removed without the consent of the engineer.; 2.2.3.4 Surplus Excavated Material: Any surplus excavated material shall be hauled and disposed of by the Contractor. 2.2.4 Laying Pipe: Unless otherwise authorized by the Engineer, the layingof pipes on the prepared foundation shall be started at the outlet and with the spigot or tongue ends pointing in the direction of flow and shall proceed toward the inlet end with the abutting sections properly matched, true to the established lines and grades. Proper facilities shall be provided for hoisting and lowering the section of pipe into the trench without disturbing the prepared foundation and the sides of the. trench. The ends of the pipes shall be carefully cleaned before the pipes are placed. As each length of pipe is laid, the mouth of the pipe shall be protected to prevent the entrance of earth or bedding material. The pipes shall be fitted and matched so that when laid in the bed they shall form a smooth uniform conduit. When elliptical pipe with circular reinforcing or circular pipe with elliptical reinforcing is used, the pipe shall be laid in the trench in such a manner that the markings "top" or "bottom", as prescribed in Section 2.2.2 above, will be in correct position. -15- • 2.2.5.2 Bell and Spigot Pipe - Cement Mortar Joints: Where sewer pipe having bell and spigot joints is used and cement mortar joints have been specified, the joints shall be made in the following manner: A closely twisted hemp or oakum caulking of suitable diameter to completely fill the annular space for one-fourth of its depth in one piece of sufficient length to pass around the pipe and lap at the top shall be solidlyrammed into the annular spaces between the pipes with a suitable caulking tool. Before placing in the joint this caulking shall first be saturated with neat cement grout. The joints between the individual pipes and specials shall, in all cases,be. made watertight by completely filling the remaining annual space between the exterior of the spigot end and the interior of the bell hub, or socket, with mortar of suchcomposition as is hereinafter specified. Special care must be taken to secure a perfectfilling of the aforesaid annular space.at the bottom and sides of the pipes as well as at the top; and previous to the introduction of the mortar, the space together with the surfaces of the pipe bounding the same, shall be thoroughly free all around from dust, sand, earth, dirt, small stones and water. After the space has been filled as described, a neat and proper finish shall be given to the joint by the further application of similar mortar to the face of the hub or the socket, from the exterior of the socket to the exterior of the connecting spigot all around. As soon as the cementing of any joint has been completed, the excavation previously made in the bottom of the trench for the reception of the hub or socket must be carefully and compactly filled with loam or fine clay, so as to hold the external mortar finish of the joint securely in its place; and such refilling shall also be carried up around the sides or circumference of the socket, as far as may be necessary. Any water which may have accumulated in the excavation must first be removed, or else the excavationsmust be completely filled out with the cement mortar specified, in which event no extra compensation will be allowed. When a pipe or special used in any sewer is affected by a broken hub or socket, or a broken blister or flake, or a fire -crack on its exterior surface, as limited. and defined in the pipe specifications, such pipe or special must be set so as to bring said permissible defect on the top or upper part of the sewer; and said defect must thereupon be completely and liberally covered over with a thick layer of cement mortar of the quality specified for the joints. Pipe of twenty-four'inches in diameter and over shall also have.the joints pointed from the inside. All mortar used for making joints shall be composed of one part of portland cement and three parts of fine aggregate. Portland cement shall conform to A.S.T.M. Specification C-150. Fine aggregate shall conform to Item 2.1.2.2 of these specifications. Hydrated limeor lime putty may be added to the mortar but shall not exceed 10% of the mix by weight. -17- After pipe has been set to proper line and grade in the trench a one-half inch thick layer of the compound shall be troweled or otherwise placed on the groove end of the pipe covering about two-thirds of the joint face around the entire circumference. Next the tongue end of the next pipe shall be shoved home with sufficient pressure to make a tight joint. Care shall be taken to avoid leaving ridges of the compound projecting into the pipe in a manner that would obstruct the flow: An outside band of the joint compound shall be installed completely around the circumference of the pipe at the joint. This will necessitate digging "bell holes" at each joint. The band shall have a thickness at the center of at least 3/4" tapering uniformly to nothing approximately 3" each side of the center. 2.2.6 Backfilling: As soon aspracticable, all spaces excavated under this speci- fication, and not occupied by the permanent structure shall be backfilled. Backfill material shall be free from lumps, wood, or other extraneous material. After the bedding has been prepared, the pipes installed as required, the joints have been made, selected granular materials shall be placed along both sides of the pipe equally, in uniform layers not exceeding 12" in depth (loose measurement), wetted and thoroughly compacted so that each side of the pipe there shall be a beam of thoroughly compacted material at least as wide as the external d-iameter of the pipe, except insofar as undisturbed material obtrudes into the area. Backfilling shall be continued in this matter. Special care shall be taken to secure thorough compaction of the material placed under the haunches of the pipe. In the case of embankments, the remainder of the fill above the top of the pipe shall be placed in accordance with the provisions for placing roadway embankment as prescribed in the pertinent specifications. No construction traffic will be permitted to cross any pipe culvert or sewer until the specified minimum depth of fill above the pipe has been placed and consolidated in accordance with these provisions. Each layer of backfill shall be compacted to 95% Standard Density in accordance with AASHO T-99. An approved commercial laboratory shall be engaged by the contractor to take density tests on each layer of backfill at intervals not exceeding 500 feet of trench length. Where storm sewers are placed under pavement, the trench shall be backfilled with 1-1/2 sack cement stabilized sand. The backfill shall be compacted as stated above. 2.2.7 End Finish and Connections: The upstream ends of culverts shall be formed to a smooth rounded lip entrance by filling the recess in the bell with joint mortar which shall be placed and cured in accordance with the provisions for jointing in these specifications. Where new culverts are constructed as extensions to culverts or sewers in place, the construction shall include all work necessary to provide a proper connection between the new structure and the old as indicated on the plans. 2.2.8 Minimum Fill: The minimum fill from the crown of the roadway to the top of the pipe shall be 18". -19- 2.3=LINNED CHANNELS 2.3.1 Description: These specifications shall govern the furnishing of all materials and labor for construction of concrete channel lining where indicated on the plans. This specification includes the excavation for channels in accordance with these specifications. 2.3.2 Materials: Lined channels shall be constructed of 4" thickness Portland cement concrete made from materials and constructed in accordance with Section 2.1 of these specifications and having a compressive strength of not less than 2000 pounds per square inch at 28 days. 2.3.3 Standard Details: Lined channels shall be built according to the dimensions shown on the plans and in accordance with standards for typical detail of concrete flume and ditch lining of the City of Pearland. Lining shall have minimum thickness of 4". Lining shall be reinforced with 6" x 6" x #6 wire. mesh, or 3/8" steel on 18" centers. 2.3.4 Excavation: Excavation shall be made to the required depth and of sufficient width to construct the work to grade, form and dimensions. All soft and yielding or other unsuitable and unstable materials shall be removed and replaced with acceptable materials; the subgrade then shall be compacted to the satisfaction of the Engineer. The subgrade shall be wetted before any concrete is placed. No undercutting of the subgrade will be permitted. Where subgrade is undercut, the space between the bottom of the forms and the s.ubgrade will be filled either with field sand or concrete and compacted. 2.3.5 Forms: The forms shall be of wood or metal, straight and free from warp, and of sufficient strength to resist springing during the process of depositing and compacting the concrete. Straight forms of wood shall be 2" nominal thickness surfaced plank, or of metal of an approved section with a flat surface on top and bottom. Forms for use on radii may be of flexible wood or metal. The forms shall be of a depth equal to the depth of the concrete section in which they are in contact, and so designed as to permit secure fastening together in correct position. Forms shall be securely staked, braced, and firmly held to the required line and grade. All forms shall be cleaned thoroughly and wetted before the concrete is placed against them. 2.3.6 Reinforcement: Wire mesh or steel shall consist of sheets of the dimensions as specified or as shown on the plans. The size and spacing of the wires or • steel shall conform to the details. Wire mesh shall be placed as shown on the plans; itshall not be bent at right angles to the forms. A minimum lap of 6" shall be used at all splices. Reinforcement shall be properly supported to maintain its position equidistant from top and bottom surface of the slab. 2.3.7 Concreting: No concrete shall be placed unless the subgrade, forms, and rein- forcement, if required, have been checked and approved by the Engineer. Concrete shall be deposited on a moist subgrade. During placing, the concrete shall be thoroughly spaded next to the forms, and shall be carefully tamped, using an approved tamper until a uniform dense concrete is obtained. After the concrete has been placed, compacted and shaped to conform to the demensions shown on the plans and after it has set sufficiently to avoid slumping, the surface shall be finished with a wooden float to secure a smooth surface and broomed. 2.2.5.3.. Bell and Spigot Pipe, Hot Poured Compound Joints: Where the plans or specifi- cations call for making bell and spigot joints with hot poured compound the following method shall be used: Materials used for this work shall be: clean, dry, unoiled, unabraided jute or oakum, a suitable joint primer and hot pour jointing compound. The compound shall be a well known brand of proven worth and uniform consistency and shall have the approval of the Engineer as being equal to Gulf States No. 703 or Root Seal, Talcote No. 081 or Atlas JC-60. The primer shall be that recommended by the manufacturer of the compound. The inside of bells and the outside of spigots shall be painted with joint primer several hours before the pipe is to be laid. Not more than two lengths of pipe may be joined before laying in the trench, taking care to preserve proper alignment of the pipes and allowing for sufficient setting of the joint material before handling the pipes. All joints shall be caulked with jute or oakum sufficient to hold the pipes in alignment andprevent any flow of the compound into the interior of the pipe. The caulking shall be packed solidly to the back of the bell and fill about 1/3 the depth of the bell. The surface of bells and spigots of the pipes shall be free from moisture when the compound is poured. No exception whatever to this rule will be permited. A suitable runner shall be placed around the outside of the joint and the compound poured rapidly at a temperature of 350 to 400 degrees Fahrenheit, or in accordance with the manufacturer's recommendations until the annular space in the bell is completely filled. If there is any evidence that voids are being left in the joints the same shall be made good and the methods corrected to prevent the occurrence of same•. 2.2.5.4 Neoprene or Rubber Gasket Joints: Joints made with neoprene, rubber, or other similar material that has been approved by the Engineer will be acceptable for use with reinforced or non -reinforced concrete pipe, either tongue and groove or bell and spigot. The ends of the pipe must be accurately made and designed for use with the gaskets. The type of joint and the gasket must have the approval of the Engineer. The joint materials and workmanship shall be such as to provide a water -tight joint.. Joints shall, unless otherwise specified, be pointed on the outside with cement mortar. . 2.2.5.5 Tongue and Groove Pipe - Cold Compound Joints: Unless otherwise specified, this type of joint shall be used for tongue and groove pipe joints not made with approved neoprene or rubber gaskets. The compound and primer shall be the same as described herein for use with bell and spigot pipe. Both ends of the pipe shall, while clean and dry, be coated with primer on all surfaces that will be in contact with the compound. The primer shall be allowed to dry before the pipe is, laid. 24H and larger pipe shall be primed at the factory. -18- 2.2.5 2.2.5.1 Multiple installations of reinforced concrete pipe shall be laid with the center lines of individual barrels parallel. The following clear distances between outer surface of adjacent pipes shall be maintained: 0 - 3' OF FILL 3' - 5' OF FILL DIAMETER OF PIPE CLEAR DISTANCE BETWEEN PIPES 18" 24" 30" 36" 42" 48" 54" 60" Over 5' 'of fill on to their diameter. to 84" pipes requires the clear DIAMETER OF PIPE .18" 24" 30" 36" 42" 48" 54" 60" 0' - 7" 0' - 8" 0' - 9" 0' - 10" 0' - 11" 1' - 0" 1' - 2" 1' - 4" 0' _ 9" 0' - 9" 1' - 0" 1' - 0" 1' - 2" 1' - 2" 1' - 4" 1' - 6" distance 'between pipes to CLEAR DISTANCE BETWEEN PIPE AND TRENCH WALL '9" on both sides 9" on both sides 9" on both sides 1/3" Diameter of 1/3" Diameter, of 1/3" Diameter of 1/3" Diameter of to 84" 1/3" Diameter of pipe pipe pipe pipe pipe on on on on on be equal both sides both sides both sides both sides both sides Joints in Pipe: .Unless otherwise specified, joints in reinforced concrete pipe shall be cold compound joints or neoprene joints as hereinafter described. Bell and Spigot Pipe - Cold Compound Joints: The inside of the pipe bells and. the outside of the spigot ends shall, while dry, be completely coated with joint primer. .This coating shall be applied sufficiently in advance so that the primer will be thoroughly dry when the pipe is laid. Pipe 24" and larger shall be primed at the point of manufacture. Apply a fillet of compound on the bottom half ofthe i.nside of the bell, press enough dry twisted jute into the compound to pass around the pipe and lap at the top and shove home the spigot of the pipe. Bring the jute around the pipe, firmly caulk into place. The jute should be sufficient to fill one fourth the depth of the bell. Fill the remaining three -fourths of the depth of the bell with compound, taking care to leave no voids and provide sufficient compound to form a fillet sloping 45Q from the outer end of the bell to the barrel of the next pipe. Compound used for these joints shall be a well known brand of material of proven worth, uniform in consistency and approved by the Engineer as being equal to Talcote No. 0.52 or Gulf States No. GS 702 or 722. Primer shall be of the type recommended by the manufacturer of the compound used. -16-