Chapter 5.70
SEWER PIPELINES
Sections:
5.70.020 Approved sewer pipe materials.
5.70.030 Pipe and joint materials.
5.70.040 Backflow prevention/relief valve.
5.70.050 Flexible couplings for pressure lines.
5.70.080 Fusion epoxy coating.
5.70.090 Conventional pipeline installation.
5.70.100 Trenchless sewer installation.
5.70.110 Cleaning and testing – Gravity mains and trunk sewers.
5.70.130 Testing of force mains.
5.70.010 Description.
Sewer pipelines shall be installed as shown on the plans and in accordance with the following provisions, the special provisions, and as directed by the District. [Ord. 2014-2 (Att. § 14-01).]
5.70.020 Approved sewer pipe materials.
The approved pipe materials for laterals and for private side sewer/lateral construction are listed in Table 1 and approved pipe materials for public sewer mains and force mains are listed in Table 2. The specific use of pipe and pipe products is subject to approval by the District. Use of pipe other than those specified hereinbelow must be reviewed by the District and specifically authorized in writing. All pipe shall be of the size, materials, and strength classifications shown on the plans or specified herein.
|
Pipe Specifications |
Can Be Used for Gravity Sewers |
Can Be Used for Ejector Pump Discharge Pipelines |
|---|---|---|
|
Ductile Iron Pipe w/Rubber Ring Joints, DIP |
Yes 2 |
No |
|
PVC ASTM D-2241, SDR=26 |
Yes 1 |
Yes 1 |
|
PVC AWWA C-900, SDR=21 |
Yes 2 |
Yes 2 |
|
PVC Sch 40 |
Yes 1 |
Yes 1 |
|
PVC Sch 80 |
Yes 2 |
Yes 2 |
|
HDPE Pipe, min SDR=17 |
Yes 1 |
Yes 1 |
1 Requires minimum three-foot cover with imported bedding and pipe zone backfill.
2 Requires minimum 18-inch cover on private property with imported bedding and pipe zone backfill or shaded with select native material containing rocks no larger than one-inch sieve size.
|
Pipe Specifications |
Can Be Used for Gravity Sewers |
Can Be Used for Force Main Sewers |
|---|---|---|
|
Ductile Iron Pipe w/Rubber Ring Joints, DIP |
Yes |
Yes |
|
PVC ASTM D-2241, SDR=21 |
Yes |
Yes |
|
PVC AWWA C-900, SDR=18 |
Yes |
Yes |
|
PVC AWWA C-905, SDR=25 |
Yes |
Yes |
|
HDPE Pipe, Min SDR=21 |
Yes |
Yes |
|
Reinforced Concrete Pipe w/T-lock * |
Yes |
No |
|
Pretensioned Concrete Cylinder Pipe |
No |
Yes |
* For large diameter sewers only, i.e., 24-inch diameter and larger.
[Ord. 2014-2 (Att. § 14-02).]
5.70.030 Pipe and joint materials.
All pipe sizes refer to inside diameter of pipe (including any pipe lining) and no pipe shall be more than one-eighth inch smaller than its designated size.
All pipe and pipe joints between structures shall be of the same type, design, and size unless otherwise specified or permitted by the District. Care shall be exercised in the intermixing of different shipments of materials to insure well-fitted joints. All rubber gaskets and/or couplings for pipe joints shall be purchased from or through the firms supplying the pipe.
The contractor shall submit shop and material details of all special pipe for approval of the District before the pipe shall be manufactured or used on the work, per Chapter 5.45 SD5MCC. All pipes and fittings shall be marked with the trade or brand name of the manufacturer and inventory identification marks. All rubber gaskets shall be grease resistant.
(1) Vitrified Clay Pipe and Fittings, VCP (For Repair of Existing VCP Pipe Only). Vitrified clay pipe and fitting shall be new, first quality pipe and shall conform to ASTM C-700, as it applies to extra strength clay pipe and fittings, unglazed, and pipe fittings shall be of a quality equal to the straight pipe.
Joints for vitrified clay pipe and fitting shall be the mechanical compression type conforming in all respects to the standards of the pipe manufacturer. Resilient material used for jointing shall conform to the specifications of ASTM C-425. Rubber couplings used to join plain end vitrified clay pipe shall conform to the material and performance requirements of ASTM C-594 with stainless steel shear bands.
(2) Ductile Iron Pipe and Fittings, DI. Ductile iron pipe shall conform to ANSI/AWWA C151/A21.51. All ductile iron pipe shall have a seal coated cement lining of one-sixteenth-inch minimum thickness for pipe up to 12 inches in diameter, and three-thirty-second-inch up to 24 inches in diameter, and one-eighth-inch above 24 inches in diameter in accordance with ANSI A21.4.
All ductile iron pipe and fittings installed underground shall have bell and spigot ends, employing a single elongated rubber gasket, “Tyton” or push-on type joint, to effect the seal. Pipe and specials shall be of the diameter and class shown on the plans, or as specified. Unless otherwise noted, all ductile iron specials and fittings shall conform to ANSI C153/A21.53 specifications. Where required on the plans, joints on buried pipelines shall have an internally locking rubber ring joint. Lead joints will not be permitted unless specifically approved by the District.
All ductile iron pipe which is installed in the ground shall be provided with polyethylene encasement conforming to AWWA Specification C-105-72. Polyethylene encasement shall be placed in accordance with the recommendations of the pipe manufacturer. Polyethylene envelopes shall be carefully placed and lapped, and care shall be exercised so that soil is not placed against the pipe.
Exposed piping in pump stations or other structures shall be installed with flanges. All flanges shall be of the thickness specified in the American Standard for Flanged Fittings, ASA B16.1, Class 125, as adopted by the American Society of Mechanical Engineers. Flanges shall be accurately faced. They shall be at right angles with the pipe axis. All bolt holes shall straddle the vertical axis and shall be one-eighth inch larger than the respective bolt diameters. Flanges on built-up spools shall be re-faced after mounting.
Bolts, nuts and washers shall be made of Type 316 stainless steel and shall have sound well-fitting threads. Bolts shall be provided with hexagonal chamfered heads and nuts. The underside of all bolt heads and nuts shall have true surfaces at right angles to the axis of the bolts. The lengths of the bolts shall be such that, after joints are made up, the bolts shall protrude through the nuts, but in no case shall they protrude more than one and one-half threads. Threads shall be lubricated with Led-plate or equal thread compound.
(3) Reinforced Concrete Pipe, RCP. Reinforced concrete pipe shall conform to ASTM C-76 and, unless otherwise indicated on the plans, in the special provisions or directed by the District, shall be Class IV (2,000 D), designed for a head of at least 25 feet, and the pipe shall be centrifugally cast. D loadings will be noted on the plans, and joint design shall conform to AWWA C-302, Section 3.3, as modified herein:
(a) The joint shall be the all-concrete bell and spigot type, unless otherwise specified in the special provisions or permitted by the District in writing.
(b) The gasket shall be confined in a groove formed in the outside surface of the spigot end of the pipe.
(c) The pipe shall be manufactured with Type II cement.
(d) Rubber gaskets used for jointing reinforced concrete pipe shall conform to Section 3.4 of AWWA C-302. Rubber gaskets conforming to ASTM C-361 require prior written approval of the District.
(e) All RCP pipe 24 inches in diameter and larger shall be lined with PVC flexible sheet liner “T-Lock” lining as manufactured by Ameron.
(4) Reinforced Concrete Water Pipe – Steel Cylinder Type, Pretensioned. Reinforced concrete water pipe – steel cylinder type, pretensioned, referred to as pretensioned concrete cylinder pipe, shall conform to the following specifications:
(a) Material, Manufacturing Operations, Testing and Inspection. All material, manufacturing operations, testing and inspection of the pipe shall be in conformance with the requirements of AWWA Standard C-303, “Reinforced Concrete Water Pipe-Steel Cylinder Type, Pretensioned,” except as modified herein. The following acceptable minimums shall apply:
(i) Wire rod reinforcement shall have a minimum spacing of 2.3 times wire rod diameter.
(ii) The cross-sectional area of the rod shall not exceed 50 percent of the total areas of rod and cylinder steel.
Except for specials required to meet the laying conditions, pipe will be furnished in standard lengths suiting the manufacturer’s shop practice and in accordance with Section 3.1.2 of AWWA Standard C-303.
(b) Joint Design. The standard field joint shall be steel joint rings with rubber gaskets as per AWWA Standard C-303, Sections 3.3 and 3.4. Rubber gaskets shall be grease resistant. In addition, the following pipe ends may be required as shown on the drawings:
(i) Ends for mechanically coupled field joints shall conform to Section 3.6.1 of AWWA C-200.
(ii) Ends fitted with butts traps for field welded joints shall conform to Section 3.6.5 of AWWA C-200.
(iii) Ends of the bell and spigot type for field welded joints shall conform to Section 3.6.2 of AWWA C-200.
(iv) Plain ends fitted with flanges shall conform to AWWA C-200, Section 3.6.7, and AWWA C-207.
(c) Restrained Joints. Where indicated on the drawings and where thrust is evident, welded joints are required. Welding of joints shall conform to the details shown in the plans.
(d) Pipe Design Criteria. Pretensioned concrete cylinder pipe shall be designed in accordance with Appendix A of ANSI/AWWA C-303 to withstand a minimum 150 psi internal pressure and calculated soil pressures together with external AASHTO H-20 track loading.
(e) Bonding and Electrical Conductivity. All unwelded pipe joints shall be bonded for electrical conductivity in accordance with the details shown.
(f) Protection of Appurtenances. All buried flanges, valves, and couplings shall be coated with a minimum thickness of one inch of cement mortar having one part cement to not more than two parts plaster sand.
All exterior surfaces which will be exposed to the atmosphere inside structures or above ground shall be thoroughly cleaned and coated according to the requirements of SD5MCC 5.70.070.
(g) Fittings and Openings. Special and standard type fittings which include bends, reducers, outlets, manholes, etc., shall be designed to a strength at least equal to the adjacent pipe and to conform to Section 4 of AWWA Standard C-303 and the dimensional requirements of AWWA C-208.
(h) Internal Bracing and End Protection. Prior to delivery, pipe end covers and end/internal bracing shall be applied, as recommended by the manufacturer, for shipping and storage protection.
(i) Shop Drawing Submittals. The manufacturer shall provide drawings in accordance with Section 1.6 of AWWA Standard C-303.
(5) Polyvinyl Chloride Pipe, PVC. As designated on the plans, PVC pipe shall conform to one of the specifications below. PVC pipe with external ribbing is not allowed.
(a) PVC, ASTM D-2241 (Pressure Pipe). PVC, ASTM D-2241 pressure pipe shall conform to ASTM D-2241 with rubber ring joints and shall have a pressure rating of 160 psi unless otherwise indicated on the plans. Joints shall meet the requirements of ASTM D-3212.
(b) PVC, C-900 or C-905 (Gravity Sewer and Pressure Pipe). PVC, C-900 or C-905 gravity sewer and pressure pipe shall conform to AWWA C-900 for diameters four inches through 12 inches and AWWA C-905 for pipe diameters 14 inches through 20 inches and shall have a SDR of 25, unless otherwise indicated on the plans. Joints shall be bell and spigot conforming to ASTM D-3139 with gaskets conforming to ASTM F-477.
All fittings for PVC, C-900 pipe shall either be fabricated or manufactured in one piece of injection molded PVC compound meeting ASTM C-1784. Fittings shall be Class 150 and conform to requirements of SDR of 18. Fittings shall be designed to withstand a minimum of 755 psi quick burst pressure at 76 degrees Fahrenheit tested in accordance with ASTM D-1599.
(c) PVC, Schedule 40 or Schedule 80. Schedule 40 and Schedule 80 PVC pipe and fittings shall be Type I, normal impact, rigid polyvinyl chloride conforming to the Department of Commerce Commercial Standard CS 207-60, or currently applicable revisions of that standard. The pipe shall be rigid, tough, lightweight, thermoplastic pipe, UV protected, furnished in iron pipe sizes. Fittings shall be molded of the same material as the pipe. Joints shall be solvent welded or bell-and-spigot with three-sixteenth-inch Neoprene or plasticized PVC gaskets.
(6) HDPE Pipe. Polyethylene pipe shall be made from polyethylene resin compound qualified as Type III, Category 5, Class C, Grade P34 in ASTM D-1248-78. This material shall have a long-term hydrostatic strength of 1,450 psi or 1,600 psi when tested and analyzed by ASTM D-2837. Minimum thickness shall be DR of 17.
The raw material shall contain carbon black, well dispersed, with a minimum of two percent. Additives which can be conclusively proven not to be detrimental to the pipe may also be used, provided the pipe produced meets the requirements of this standard.
The pipe shall contain no recycled compound except that generated in the manufacturer’s own plant from resin of the same specification from the same raw material supplier.
The cell classification shall be PE 33443C (10 MPa) for PE 3407 materials or PE 345534C for PE 3408 materials, per ASTM D-3350/F-714-81.
Pipe sections shall be heat fused together. Only those tools specifically designed for joining polyethylene pipe and only those personnel approved by the pipe supplier and District shall join polyethylene pipe.
(7) Encasement Pipe. When designated on the plans, permit, or by the District in writing, approved encasement pipe shall be placed in a bored hole under the area to be crossed. The encasement pipe shall be plain steel and shall be of the length, diameter and thickness specified on the plans or in the special provisions. Plain metal pipe shall conform to the requirements of AWWA C-201 or AWWA C-202 for steel water pipe, butt welded and shall conform to the thickness given in the following table:
|
Inside Diameter (inches) |
Smooth Steel Thickness (inches) |
|---|---|
|
18 |
1/4 |
|
21 |
1/4 |
|
24 |
1/4 |
|
30 |
5/16 |
|
35 |
5/16 |
|
48 |
not permitted |
|
54 |
not permitted |
|
60 |
not permitted |
[Ord. 2014-2 (Att. § 14-03).]
5.70.040 Backflow prevention/relief valve.
Backflow prevention/relief valve shall be Contra Costa type or Plumbest or equivalent as approved by the District. The backflow preventer/relief valve shall be installed at an elevation at least six inches lower than the lowest home fixture as approved by the District. If the backflow preventer/relief valve cannot be installed six inches below the lowest fixture then a PVC check valve shall be installed in the lateral. [Ord. 2014-2 (Att. § 14-04).]
5.70.050 Flexible couplings for pressure lines.
(1) Flexible Couplings. Flexible couplings used for connection of sections of pipe having identical outside diameters shall be Rockwell Type 411, Dresser Style 38, or equal. Flexible couplings for connections of cast iron pipe having slightly different outside diameters shall be Rockwell Type 413, Dresser Style 162, or equal. Coupling gaskets shall be Rockwell Grade 60, Dresser Grade 42, or equal. Buried couplings shall have Type 316 stainless steel bolts, nuts and washers.
(2) Flanged Coupling Adapters. Flanged coupling adapters shall be Rockwell Type 912, Dresser Style 127, or equal, complete with Type 316 stainless steel bolts, nuts and washers. All flanged coupling adapters shall be provided with anchor studs or joint harness bolts and lugs to prevent joint separation, as approved by the District. Restraints shall be designed for one to two times the maximum working pressure of the applicable service.
(3) Coatings for Flexible Couplings. All flexible couplings and flanged coupling adapters shall be fusion epoxy coated in accordance with the requirements of SD5MCC 5.70.080. Bolts, nuts and washers shall be Type 316 stainless steel. After installation, epoxy resin touch-up shall be applied to damaged coating. On underground lines, the flexible coupling and bolts shall be wrapped as specified in SD5MCC 5.70.070. [Ord. 2014-2 (Att. § 14-05).]
5.70.060 Valves.
(1) Eccentric Plug Valves. Plug valves shall be nonlubricated eccentric plug valves conforming to the following requests:
(a) Type. Eccentric plug valves shall be of the nonlubricated eccentric type with an elastomer covering all sealing surfaces. The elastomer shall be suitable for sewage service. Flanged valves shall be manufactured in accordance with ANSI B16.1 Class 125/150, including facing, drilling and flange thickness. Ports shall be round with a minimum of 81 percent port area on sizes two and one-half inches through 12 inches to facilitate “pigging” when required. Valves 14 inches and larger shall be of a rectangular port design with a minimum of 81 percent port area.
(b) Valve Bodies. Valve bodies shall be of ASTM A-126 Class B cast iron in accordance with AWWA C-504-87, Section 5.2.1. Valves three inches and larger shall be furnished with a welded-in overlay seat of not less than 90 percent nickel in accordance with AWWA C-507-85, Section 3.2.3.5. Sprayed, plated or screwed-in seats are not acceptable.
(c) Plugs. Plugs shall be of ASTM A-536 Grade 65-45-12 in compliance with AWWA C-504-87, Section 2.2.2. The plugs shall be of one-piece solid construction with PTFE thrust bearings on the upper and lower bearing journals to reduce torque and prevent dirt and grit from entering the bearing and seal area.
(d) Bearings and Seals. Valves shall be furnished with replaceable sleeve type bearings conforming to AWWA C-504-87, Section 3.6.1, and AWWA C-507-85, Section 3.2.4. Bearings shall be of sintered, oil impregnated Type 316 stainless steel ASTM A-743 Grade CF-8M. Valve shaft seals shall be of the “U” cup type in accordance with AWWA C-504-87, Section 3.7.2. Seals shall be self adjusting and repackable without removing the bonnet from the valve.
(e) Shutoff. Valves shall be designed and manufactured to shut off bubble tight at 175 psi for valves two and one-half inches through 12 inches and at 150 psi for valves 14 inches through 36 inches. Valves 42 inches and larger shall be certified bubble tight at 125 psi.
(f) Test. Each valve shall be given a hydrostatic and seat test with certified test results. Certified copies of proof-of-design test reports shall be furnished as outlined in AWWA C-504-87, Section 5.2.4, when requested.
(g) Manufacturer. Plug valves shall be Millcentric Series 601/600 as manufactured by Milliken Valve Company of Bethlehem, Pennsylvania.
(h) Operator. Wrench operated valves two and one-half through eight inches shall be capable of being converted to worm gear or automated operation without removing the bonnet or plug from the valve. All wrench operated valves shall be equipped with a two-inch square nut for use with removable levers or extended “T” handles.
Worm gear operators, where required, shall be of heavy duty construction with the ductile iron quadrant supported on the top and bottom by oil impregnated bronze bearings. The worm gear and shaft shall be manufactured of hardened steel and run on high efficiency roller bearings.
Provide operators for all valves. Valve rotation shall be counterclockwise (to the left) to open and the word “OPEN” and an arrow indicating the direction to open shall be cast on each valve body or operator.
Lever operators shall have a maximum pull of 80 pounds and shall be capable of withstanding a 200-pound pull without damage. Wrench nuts shall conform to AWWA C-500, Section 19, and shall be capable of withstanding a 300-foot-pound torque without damage. Extension stems shall be provided where indicated on drawings, specified, required for proper operation and for buried valves with operating units more than three feet below grade. Stem guides shall be cast iron, bronze bushed and adjustable in two directions. If extension stem length exceeds 10 feet or the weight exceeds 20 pounds, the top guide shall be designed to carry the stem weight and provide a collar on the stem to bear against the thrust guide. The maximum spacing of nonrising stems shall be 100 times stem OD with a 10-foot maximum.
Buried valves shall be provided with a stem extending to within six inches of grade. Provide spaces to center stem in valve box and provide wrench nut.
(i) Coating. Provide shop applied coating of rust resistor primer and Tnemec Series 69 high build epoxy 12 mils thickness inside and outside.
(2) Iron Body Swing Check Valves. Check valves two to 12 inches shall be designed for working pressures of 200 pounds Cold W.O.G., nonshock, and shall conform to the following Standard Specifications, latest edition:
A.S.A. B-16.10, Section applying to 125-pound cast iron swing check valves.
A.S.A. B-16.1, Cast Iron Pipe Flanges and Flanged Fittings, Class 125.
A.P.I. Standard No. 6-D, for 175-pound pipe line swing check valves.
Hinge pins shall be stainless steel. Metal discs shall be prevented from sticking or wedging in open positions by stops. Discs shall be mounted allowing free movement of the disc to rotate assuring uniform seat wear. Check valves shall be designed with inclined seat making them suitable for use in either a horizontal or vertical position. Swing check valves four inches or larger shall be provided with external lever and spring for the balancing of the gate appropriately to operating conditions.
(3) Air Release Valves. Sewage air release valves shall be equivalent in workmanship, materials, and functional characteristics to ARI Model D-020 combination air valve for sewage or Model D-025 short version. [Ord. 2014-2 (Att. § 14-06).]
5.70.070 Protective coatings.
All metal valves, fittings, couplings, bolts, and nuts buried underground shall be protected from corrosion by applying a primer Polyken 927, or Tapecoat color primer, or equal, and wrapping with polyethylene tape Polyken 930, or Tapecoat CT, or equal. Exposed metal fittings, valves, etc., in manholes or valve boxes shall be coated with two coatings Tapecoat Mastic, Koppers Bitumastic No. 505, or equal. Surfaces shall be thoroughly cleaned before application. All coatings shall be applied in strict conformance with instructions of the manufacturer. [Ord. 2014-2 (Att. § 14-07).]
5.70.080 Fusion epoxy coating.
Where required, steel pipe and fittings, valves, gates, and equipment shall be lined and/or coated with epoxy resin by the fluid bed process as specified hereinbelow.
The lining and coating material shall be a one-part, heat curable semi-flexible thermosetting light green epoxy resin powder designed for application on preheated surfaces by fluid bed process, Scotchkote 206N, as manufactured by 3M Company. Alternate coating equivalency test results shall be submitted to the satisfaction of the District at the expense of the contractor.
Metal surface shall be prepared by blasting sand or grit to a uniform white metal appearance. All rough surface or pitted areas shall be ground smooth.
The lining and coating shall be applied within eight hours of sand blasting operations. The cleaned fitting shall be preheated and maintained at the required coating temperature during the lining and coating process. Application shall be by the fluidized bed process. The finished lining and coating thickness shall be not less than 15 mils. The freshly coated fitting shall be post-heated in a suitable oven immediately following the coating application of a sufficient time to insure complete cure of the epoxy resin.
The epoxy coating and lining shall be uniform in film thickness without bare or thin spots, runs or sags, pinholes or other defects.
The epoxy application shall be proven by the following tests:
(1) Adhesion Test: (a) immersion of a two-inch by six-inch sample in boiling water for four hours, (b) immersion of a two-inch by six-inch sample in 150-degree water for 96 hours. No signs of blisters, bubbles, peeling, or other forms of separation of coating shall be found.
(2) Wet Sponge Holiday Detector Test. The lining shall be free of pinholes as tested by low voltage wet sponge Holiday Detector.
The application of the dry powder fusion epoxy resin shall be done only by experienced and skilled craftsmen. The manufacturer shall submit a certificate that the fitting meets, in all respects, the requirements of these specifications.
Coating damaged in the field shall be restored with a 100 percent solids room temperature curing epoxy resin, compatible with the fusion epoxy coating and applied in accordance with the recommendation of the manufacturer. [Ord. 2014-2 (Att. § 14-08).]
5.70.090 Conventional pipeline installation.
(1) Main Sewer and Trunk Sewer Pipe Laying. All pipe shall be laid to conform to the prescribed line and grade as shown on the plans. The pipe grade shall be set from the grade stakes using a laser. The grade line shall be established before any pipe is laid in the trench. Each pipe length shall be checked for conformance to the grade line.
Trench width, pipe bedding, pipe zone backfill and special laterals should conform to the plans and the standard drawings herein.
As the work progresses, the interior of the sewer shall be cleared of all dirt and debris of every description. Where clearing after laying is difficult because of small pipe size, a suitable swab or squeegee shall be kept in the pipe and pulled forward past each joint immediately after jointing has been completed.
Unless otherwise approved by the District, the sewer line shall be laid without break upgrade from the point of connection to existing sewer and with the bell end forward or upgrade. Pipe shall not be laid when the condition of the trench or the weather is unsuitable. When pipe laying is not in progress, the forward end of the pipe shall be kept effectively closed with an approved temporary watertight plug.
Each length of pipe shall have full bearing for its entire length and adequate bell holes shall be dug at each end of the pipe. Adjustments of pipe to line and grade shall be made by scraping away or filling in and tamping the bedding material under the body of the pipe. No wedging or blocking to support the pipe will be permitted.
Unsuitable subgrade material shall be excavated and stabilized with crushed rock to provide a firm bedding for the pipe or as recommended by the soils engineer.
For curved sewers, the deflection in the joint between any two successive pipe sections shall not exceed 80 percent of the maximum deflection as recommended by the pipe manufacturer. Minimum two-foot pipe lengths may be supplied or pipe may be cut, if approved joint material is available, to install short radius curves and to conform with the joint deflection limitations.
Sewer pipes, branches, stubs, or other open ends which are not to be immediately connected shall be plugged or capped with a standard watertight plug or cap, as approved by the District for use in the particular installation. The plug or cap shall be placed on a standard end. Open pipe ends on which rodding inlets, flushing inlets, etc., are to be constructed shall be plugged at all times until the structure is completed and the cover in place.
All sewer line connections to manholes, trunk sewers, main sewers, or side sewers shall be left uncovered until after the inspection has been made. After approval of the connection, the trench shall be backfilled as specified.
If the sewer is to be laid in an area that is to be filled and the cover prior to filling is less than four feet, the pipe shall not be laid until the area has been filled to a level of four feet above the proposed pipe and compacted to 90 percent relative compaction unless otherwise authorized by the District.
The markings on reinforced concrete pipe indicating the minor axis of the elliptical reinforcement shall be placed in a vertical plane when the pipe is laid in place.
(2) Side Sewer Pipe Installation. All side sewer pipe shall be laid in conformance with the requirements set forth herein for sewer mains and trunk sewers and to the following requirements.
All side sewers shall be equipped with clean outs, backflow prevention devices, and test fittings required in the Uniform Plumbing Code, by District ordinance, and as shown in the standard drawings herein.
(3) Pipe Jointing. All pipe jointing shall be accomplished by using the proper types of jointing materials as specified in SD5MCC 5.70.030 and in a manner conforming to the methods hereinafter specified and in accordance with the manufacturer’s prescribed installation procedures.
(4) Jointing of Dissimilar Pipes. Jointing of dissimilar pipes shall be accomplished with approved special couplings or adapter. The jointings of vitrified clay and cast iron pipe may be accomplished by using an approved Fernco coupling, Calder coupling, Band Seal coupling, or other special approved couplings. All couplings shall have stainless steel shear bands.
(5) Connections to Existing Sewerage Systems. It shall be the responsibility of the contractor to determine the exact location and depth of the existing sewers prior to the installation of any sewer pipe. In the case of side sewer work, the contractor shall also determine the elevation of the plumbing outlet at the building to be connected and decide whether the required grade and cover can be maintained between the outlet and the main sewer prior to construction of any portion of the side sewer. Where the connection is to be made in an existing manhole, the contractor shall make the connection by carefully breaking through the manhole wall, cutting the floor or concrete base, installing the pipe through the wall with minimum one-and-one-half-inch and maximum two-inch protrusion, and forming a new channel, and repairing any damage to the structure. The floor and channel of the manhole shall be finished with a smooth finish. Where the connection is to be made by constructing a new manhole on an existing sewer, the connection and manhole shall conform to the details shown on the standard drawings.
(a) Main Sewers. Connection of main sewers and trunk sewers shall only be made in manholes, or special structures.
(b) Side Sewers. Where wyes, tees and/or laterals were previously installed on the main sewer, the side sewer or building sewer shall be connected to the wye, tee, or lateral as provided for the particular connection. Where a wye, tee, or lateral has not been installed at the point of desired connection, either a standard wye or tee fitting shall be “cut-in” to the main sewer using approved couplings and fittings of the same material as the main sewer, or the connection shall be made using the slope of the last 20 feet of a side sewer connecting to a sewer main. This slope shall be less than 30 degrees from the horizontal. A “Tap Tite,” “Inserta Tee” or equal method may be used. Inserta Tee may only be used on sewer mains 12 inches in diameter or larger.
(6) Special Jointing Requirements in Filled Ground. Where construction takes place in filled marsh land or areas underlain by bay mud, or any other areas which in the judgment of the District are subject to possible subsidence or differential settlement, special pipe jointing will be required for pipe entering and leaving manholes or structures. When indicated on the plans or in the special provisions or directed by the District, all sewer lines smaller than 12 inches entering and leaving manholes or structures shall have two approved flexible joints within four feet of the manhole base or structure, with not less than 12 inches between joints. All sewer lines 12 through 18 inches shall have one approved flexible joint within 12 inches of the manhole base or structure.
(7) Force Main (Pressure Sewer) Pipe Installation. Force main pipe shall be laid in conformance with the requirements set forth herein for main and trunk sewer pipe, and to the following requirements:
Unless joints are otherwise restrained concrete thrust blocks shall be provided on all force main bends having a deflection angle of 11 degrees or more, and at elbows, tees and valves. Thrust blocks shall have a sufficient bearing area to withstand the maximum force to be exerted. For cement lined and coated steel pipe, pipe joints may be welded 100 feet either side of the bend in lieu of providing a concrete thrust block.
Unless otherwise specified on the plans, in the special provisions or directed by the District, all valves to be installed in force mains shall be plug valves as specified in SD5MCC 5.70.060(1). Unless otherwise shown on the plans each valve shall correspond to the size of the run of pipe on which it is to be installed.
Force main valves shall be installed in accordance with Standard Drawing No. SD 14 (SD5MCC 5.105.010). The cover shall be marked with the word “sewer.” An extension stem, valve wrench and all materials and equipment necessary for easy and proper valve operation shall be supplied. Proper clearance shall be provided between the riser and the cover of the box so that traffic loads will not be transferred to the valve or pipe. [Ord. 2014-2 (Att. § 14-09).]
5.70.100 Trenchless sewer installation.
When shown on the plans and as specified in the special provisions, sewer pipe may be installed by trenchless methods as specified hereinbelow:
(1) Boring and Tunneling. Where an encasement pipe is bored or jacked under a street, highway, or railroad, the pipe and construction methods shall conform to the requirements of the agency with jurisdiction over the street, highway or railroad.
(a) Bores. Where an encasement pipe or sewer pipe is installed in a bored hole, whether wet or dry, the hole shall be bored by use of a machine which will cut a true circular bore to the required line and grade. Bored tunnels shall be no more than two inches larger in diameter than the maximum outside diameter of the encasement pipe or sewer pipe to be placed therein. Main or side sewer pipes installed in bores without encasement pipes shall be ductile iron, Class 50, unless otherwise specified in the special provisions or directed by the District.
After the main and side sewer pipe is secured in place, the space around the pipe shall be completely filled with sand or grout as directed by the District.
(b) Tunnels. Where tunnels without encasement pipes are required or permitted, they may only be drilled with approved equipment which will cut a true circle on grade to a diameter not greater than two inches larger than the greatest diameter of the sewer pipe, or they may be excavated by standard tunnel methods using shoring, lagging and adequate support, where necessary.
(c) Installation. The encasement pipe shall be installed by jacking or tunneling in such a manner as not to interfere with the utility, railroad track, street or highway being crossed. Sufficient jacking capacity shall be provided in advance to insure successful completion of the operation. Guide rails shall be accurately set to the line and grade so that the pipe, while being jacked, will be guided along the prescribed line and grade. A rigid backstop shall be erected to withstand the full thrust of the jacks during the process of installing the pipe. Jacks and bearing frame with necessary blocking shall be provided of sufficient strength and number to propel the pipe forward as excavation progresses ahead of the forward end of the pipe.
If a void develops between the encasement pipe and the surrounding soil, the void shall be completely filled with grout as directed by the District or as directed by the agency with jurisdiction over the street, highway or railroad.
(d) Blocking Carrier Pipe. After the casing has been installed, two redwood skids of appropriate cross-sectional dimensions, running the full length of each pipe section, shall be strapped securely to each section of sewer pipe and each section shall then be pushed or pulled into the encasement pipe after jointing. The skids shall be tapered as necessary to assure proper sewer grade. Extra care shall be taken to insure proper pipe jointing since a misplaced rubber joint ring would be extremely difficult to correct once the pipe has entered the casing. Appropriately sized redwood blocks shall also be secured at suitable intervals to each piece of sewer pipe to prevent the possibility of the pipe floating within the casing. Exact details of installation, including all redwood skid and block sizing and spacing, shall be submitted by the contractor for specific approval of the District well in advance of starting this work.
(e) Filling Annular Space. After the pipeline has been cleaned and tested in accordance with SD5MCC 5.70.110, the space between the pipe and the casing, at both ends of the casing, shall be plugged with brick and mortar in accordance with accepted construction practices. Unless otherwise indicated on the plans or in the special provisions, the space between the sewer pipe and encasement pipe shall be filled with sand or grout, as shown on the plans or as directed by the District.
(2) Pipe Bursting. Trenchless sewer installation by pipe bursting involves the shattering of an existing sewer and pushing the broken pieces into the surrounding soil and then inserting a polyethylene pipe liner.
(a) Methods. Pipe bursting methods may include a hydraulic expanding head or a conical head pulled through the sewer to be burst with sufficient force to break the existing sewer and insert the new liner pipe. Use of a pneumatic percussive head is not allowed unless specifically permitted by the District.
The contractor shall be certified by the pipe bursting system manufacturer that such firm is a licensed installer of their system. Polyethylene pipe jointing shall be performed by personnel trained in the use of joint fusion and stab joint equipment and recommended methods for pipe liner connections.
(b) Preparation. Prior to commencing the pipe bursting procedure, the contractor shall televise the existing sewer to determine the location of each house lateral and to determine if there are any obstructions or special problems in the sewer to be pipe burst.
Each lateral shall be exposed and the contractor shall verify that each one is live prior to pipe bursting. The contractor shall also determine whether or not extra laterals which are found during the televising are live or dead, since some houses may have more than one lateral.
(c) Access Excavations. The contractor shall construct access excavations as necessary for the pipe bursting and liner insertion. When practicable, access excavations shall be located where interference to vehicular traffic and inconvenience to the public is minimized. Excavations for pulling or pushing equipment shall have adequate support provided to prevent damage to adjacent areas.
Existing manholes shall be excavated for access excavations wherever practical. Manhole inverts and bottoms shall be removed to permit access for installation equipment.
(d) Bypassing Sewage. During pipe bursting of a live sewer, the contractor shall bypass the sewage around the section or sections of sewer line to be rehabilitated. The bypass shall be made by plugging existing upstream manhole and pumping the sewage into a downstream manhole or adjacent system or other method as may be approved by the District. The pump and bypass lines shall be of adequate capacity and size to handle the flow without backing up the sewage to a point that threatens connected homes.
The contractor shall be responsible for continuity of sanitary sewer service to each facility connected to the section of sewer during the execution of the work. If it is necessary to continue the bypass during nonworking hours, the contractor shall provide a high water alarm.
Support equipment used to perform the work shall be located away from buildings so as not to create a noise impact. Provide silencers or other devices to reduce machine noise as required to meet applicable noise ordinances.
(e) Pipe Installation. Thread the necessary lines through sewer section to be rehabilitated and then pull the bursting head followed by the liner pipe.
After the pipe has been installed in the entire length of the sewer section, the liner pipe shall be anchored at manholes. The pipe shall protrude in the manholes for enough distance to allow sealing and trimming. Sealing the pipe at manholes providing a flexible gasket connector shall be installed in the manhole wall at the end of the pipe, centered in the existing manhole wall. Grout the flexible connector in the manhole wall filling all voids the full thickness of the manhole wall. Restore manhole bottom and invert.
(f) Sewer House Connections. Sewer house connections shall be connected to the liner pipe by heat fusion saddles. Once the saddle is secured in place, drill hole full inside diameter of saddle outlet in pipe.
The existing house sewer shall be connected to the saddle using a flexible coupling. After connection to the saddle, the side sewer connection pipe shall have a slope toward the newly lined sewer equal to the slope of the existing lateral pipe or a minimum of two percent.
(3) Directional Drilling Procedure.
(a) General. Horizontal directional drilling shall consist of the drilling of a small diameter pilot bore from the entrance pit to the exit pit. Once the pilot boring is in place and conforms to the horizontal and vertical design requirements shown on the plans and specified below, the contractor shall ream out the hole to the smallest practicable diameter and then use “pipebursting” head to pull the pipeline into place.
(b) Guidance of Pilot Bore. The contractor shall prepare and submit a bore plan which includes drilling machine, bore hole location technique to be used, final bore hole diameter and final bore hole grouting methods if required, to the District for review prior to commencing work. Pipelines installed by directional drilling must be located horizontally and vertically to the design grade in the location as shown on the plans and no shallower than the vertical design location as shown on the profile or as specified herein. The head of the pilot bore shall be equipped with a sewer grade transmitter which will allow the contractor to determine its location, pitch in one-tenth percent increments from one-tenth to 45 percent, roll, battery status and depth from the ground surface. Based on this information, the contractor shall determine the pilot location and plot on the plans the actual horizontal, vertical alignment and sewer grade of the pilot boring at intervals not exceeding every 10 feet during the drilling of the pilot boring. The current plot shall be available for inspection upon request by the inspector. The alignment and depth of the pilot boring must be approved by the District before the pipeline is pulled.
(c) Drilling Operation. Upon request by the inspector the contractor must demonstrate the accuracy of the transmitter installed within the bore tool housing prior to pilot boring operations commencing. Use of bent drill rods is not acceptable and shall be replaced with a straight rod at the request of the inspector.
During the drilling operation, the contractor shall make adequate provision to contain and dispose of muddy water or drilling mud. Muddy water or drilling mud must not be discharged to any storm drains, creeks, or watercourses. Where no provisions can be made for storage of muddy water or drilling mud on site, it must be hauled away to a suitable legal disposal site on a daily basis.
(d) Bore Hole. Any over bore between the pipe and the actual bored hole shall be sealed for its entire length with cement slurry grout, taking care not to collapse, overheat, or otherwise damage the pipe. [Ord. 2014-2 (Att. § 14-10).]
5.70.110 Cleaning and testing – Gravity mains and trunk sewers.
After installation, all gravity and trunk sewers shall be tested and cleaned as herein specified, in the presence of the District Inspector. The contractor shall notify the District Inspector 24 hours prior to any testing during normal working hours. The program for testing and cleaning shall fit the conditions as mutually determined by the District and the contractor. The contractor shall furnish all labor, tools, equipment and water necessary to make all tests, clean the lines and to perform any work incidental thereto. The contractor shall take all necessary precautions to prevent any joints from pulling while the pipelines or their appurtenances are being tested. He shall, at his own expense, correct any excess leakage and repair any damage to the pipe and its appurtenances or to any structures, resulting from or caused by these tests. Materials and methods used for any necessary repair work shall be specifically approved by the District.
The contractor shall flush all sewer lines prior to testing and accumulated materials shall be removed at each manhole and no materials shall be allowed to enter the existing sewer system. A plug shall be installed and maintained by the contractor in the line connecting to the existing system until all cleaning and testing is completed and the lines are approved for operation. All side sewers shall be plugged at their ends until hooked up to the building sewer.
(1) Testing. Each section of sewer line shall be tested as provided herein using either water or air at the option of the contractor. However, in the event that the contractor elects to test sewer sections using the air test method, each manhole shall be tested separately using the procedure outlined in SD5MCC 5.80.070.
The infiltration test described below may be required by the District in addition to either the water or air tests.
All testing specified hereinbelow shall be done after the placing and compaction of intermediate trench backfill and placement of the road subbase, but prior to final paving. If a new street is being constructed involving the placement of cement treated or lime treated base, the testing and repair of all sewers shall be completed prior to installation of such base.
(a) Water Test. Each section of sewer shall be tested between successive manholes by plugging the lower end of the sewer to be tested and the inlet sewer of the upper manhole and filling the pipe and manhole with water to a point four feet above the crown of the sewer in the upper manhole, or, if ground water is present, four feet above the average adjacent ground water level. For the convenience of the contractor, where grades are slight, two or more sections between manholes may be tested at once. However, when testing more than one section, the allowable leakage for the total length shall be that computed for the shortest section of pipeline between manholes tested. Where grades are steep and excessive test heads would result by testing from one manhole to another, test fittings the full size of the main shall be installed at intermediate points so the maximum head on any section under test will not exceed 12 feet. The lines shall be filled at least two hours prior to testing and shall be tested at least one hour maintaining the head specified above by measured additions of water. The sum of these additions shall be the leakage for the test period.
The allowable leakage shall be figured as 50 gallons per day per inch of sewer diameter per mile of main sewer being tested. After that time the leakage shall be measured and, if any leakage exists, the contractor shall discover the cause and remedy it before the sewer is accepted. Where the actual leakage is less than the allowable and leaks are observed, such leaks shall be repaired at the contractor’s expense, as directed by the District.
(b) Air Test. Low pressure air tests for sewers between structures shall be accomplished by carefully placing test plugs at each end of the section of line to be tested. Air test shall be allowed on lines only up to 10 inches in diameter. When all necessary test equipment is in place, a compressed air supply shall be attached to the air fitting on the equipment and the air pressure within the line increased to the test pressure. After the air supply is securely turned off or disconnected, there shall be a two-minute waiting period to allow stabilization of air within the sewer line before the actual test period begins. The test pressure shall be at least five pounds per square inch at the beginning of the test.
The air pressure must not drop over a 10-minute period.
The maximum length of a sewer line that may be tested at one time shall be 500 feet, exclusive of any laterals. After completion of a test, the air pressure shall be released slowly through the valve, which is incorporated in the test equipment. Air test plugs shall not be removed until the air pressure is no longer measurable.
If ground water is known to be present, the beginning test pressure shall be increased as directed by the District.
When the contractor elects to test sewer sections using the air test method, each manhole shall be water tested by plugging all inlet and outlet pipes and filling the manhole with water, per SD5MCC 5.80.070.
(c) Infiltration Test. If in the construction of a sewer, excessive ground water is encountered, the tests for leakage described above may, at the discretion of the District, be supplemented by the infiltration test described herein. Test sections shall be isolated and any pumping of ground water shall be discontinued for at least three days and the ground water shall be allowed to rise to maximum level. The infiltration rate shall then be measured at the low end of the test section.
The infiltration rate shall not exceed 50 gallons per day per inch of sewer diameter per mile of main sewer being tested. No additional allowance shall be made for manholes or other structures. If the observed infiltration rate exceeds the allowed limit, the required repairs shall be made and the section shall be retested. Repairs and retesting shall be repeated until the observed infiltration falls within the allowed limit. Notwithstanding satisfactory passing of other than leakage tests or infiltration tests, where infiltration is later discovered in excess of the allowed limit before completion and acceptance of the sewer, the sewer shall be immediately uncovered where necessary and repairs made to reduce the infiltration rate within the allowed limit before the sewer is accepted. However, should the infiltration be less than the specified amount, the contractor shall stop any individual leaks that may be observed when ordered to do so by the District.
(2) Cleaning. After gravity main and trunk sewers have been tested for leakage and after either temporary or permanent surfacing replacement has been installed, but prior to acceptance, they shall be tested for obstructions and cleaned by hydro-flushing with high pressure water using hydrovac equipment or balling with a Wayne ball. The District reserves the right to ask the contractor to clean downstream sewer lines if, in the opinion of the District, there is reason to believe dirt and debris may have entered the District’s system.
(3) Deflection Test. After the sewer main has been tested hydrostatically or with air and cleaned, but before sewage is allowed to enter it, the contractor shall conduct a test for excessive deflection of all PVC sewer mains except PVC C-900 pipe. The deflection test shall consist of pulling a mandrel of a predetermined diameter through the pipeline. The mandrel shall be based on a five percent allowable deflection and six percent go-no-go. Mandrels shall have the following outside diameter.
|
Sewer Diameter (Inches) |
Mandrel Outside Diameter (Inches) |
|---|---|
|
6 |
5.54 |
|
8 |
7.42 |
|
10 |
9.27 |
|
12 |
11.03 |
|
15 |
13.51 |
If the sewer pipe does not meet the mandrel test, it shall be removed and relaid.
(4) Television Inspection. After the sewers have been backfilled, completed, tested and cleaned, but before acceptance of the job, the contractor shall arrange and pay for closed circuit television inspection of the sewer mains and each lateral. All televising shall be performed by a firm experienced in closed circuit televising of sewer lines acceptable to the District. Televising shall be in color and done in the presence of the District Inspector, and the contractor shall furnish to the District a videotape and DVD (sewer main only) of the complete television inspection. The television camera shall be equipped with a measuring device so that the depth of any sags can be accurately determined. The television camera shall be equipped with an articulating camera head which would allow the camera to inspect the lateral stub connection and pipe joints. Defects, including but not limited to sags, leaks, breaks, excessive pipe deflection, etc., which are in excess of the limits specified above, revealed by the television inspection shall be promptly corrected by the contractor at no expense to the District. Television inspection will be paid for on a lineal foot basis in accordance with the bid item therefor.
The grade of all gravity sewers shall be within five-hundredths foot of the elevations and grades shown on the plans with the provision that, in no event, shall a gravity sewer, drain, or air vent line be allowed to have a sag or standing water greater than one-tenth foot deep.
Defects, including but not limited to sags that are in excess of the limits specified above, leaks, breaks, excessive pipe deflection, etc., as revealed by the television inspection shall be promptly corrected by the contractor at no expense to the District.
After correction of the defect or defects found by the television inspection, the pipeline where the corrections were made shall be retelevised at the contractor’s expense. The retelevising shall be performed by a firm experienced in closed circuit televising of sewer lines acceptable to the District.
(5) Warranty Inspection. All sewer mains shall be retelevised 11 months after acceptance by the District as a warranty inspection. Any and all defects revealed by this retelevising shall be corrected. [Ord. 2014-2 (Att. § 14-11).]
5.70.120 Side sewer testing.
All side sewers shall be tested and cleaned in the same manner as that specified for main sewers, in the presence of the District Inspector. An approved test fitting and plug shall be installed at or near the point of connection to the main sewer, or lateral sewer if existing, and at the connection with the building plumbing. The pipe shall be tested after it has been bedded and shaded. Any leaks discovered shall be repaired by the contractor at his expense.
Test fittings shall be wye branches or tees of the same type, size and quality as that of the side sewer, unless otherwise approved, and shall be installed where required. The branch of each test fitting shall be laid in an upright position. After the test is completed and the test plug has been removed, the test wye shall be capped or completed per Standard Drawing SD 6 (SD5MCC 5.105.010). [Ord. 2014-2 (Att. § 14-12).]
5.70.130 Testing of force mains.
All force main pipes shall be thoroughly cleaned by flushing prior to testing in such a manner that no materials are allowed to enter the existing sewer system.
After installing the force main pipe and after placing and compacting the intermediate trench backfill and placement of road subbase, but before final paving has been placed and compacted as specified herein, all force mains shall be tested for leakage as provided below. The program for testing shall fit the conditions as mutually determined by the District and the contractor. The contractor shall furnish all labor, tools, equipment and water necessary to make the tests and to perform any work incidental thereto. Any leaks which may develop shall be repaired by and at the expense of the contractor, and he shall, at his own expense, correct and repair any damage to the pipe and its appurtenances, or to any other structures, resulting from or caused by the tests.
A hydrostatic test shall be applied for not less than two hours, or for as long as may be necessary to check all joints and find any leaks which might develop. The test pressure should be 120 percent of the total dynamic head of the system or 50 pounds per square inch, whichever is greater. Force main pipe installations will not be accepted unless there is zero leakage. Use of air to test force mains is not permitted. [Ord. 2014-2 (Att. § 14-13).]