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(a) Permits. The contractor shall have a permit and drawings approved by the BPA, and OEPA prior to starting construction.
(b) Design Standards.
(1) Manholes shall be 4 ft. inside diameter, with PVC coated rungs and shall not span more than 450 feet between manholes.
(2) PVC pipe meeting ASTM D-3034 specifications meeting SDR-35 strength.
PVC GRAVITY PIPE SEWERS
Pipe and fittings 4” – 15” diameter shall conform to ASTEM Specifications D-3034 and shall meet extra strength minimum SDR-35.
Pipe and fittings 18” – 27” diameter shall conform to ASTM Specifications F-269, wall thickness T-1.
Pipe shall be furnished in standard manufactured lengths.
Each length of pipe shall be marked with manufacturer’s name, nominal diameter and “home” mark on the spigot end to indicate when the pipe is inserted to the “home” position.
Old pipe or fittings previously used will not be allowed in this work.
Joints shall be push-on type, with an elastomeric ring gasket compressed in an annular space between a bell end and spigot end of pipe, conforming to ASTM D 3212.
Elastomeric ring gaskets shall conform to ASTM F-477 for low-head application.
Bedding material shall be gravel, crushed limestone or slag, specifications, free from dirt and other deleterious materials.
Methods of handling, unloading, cutting and joining pipe shall be in accordance with the manufacturer’s recommendations.
Pipe and fittings shall be installed per STEM designation D-2321 “Underground Installation of Flexible Thermoplastic Sewer Pipe.”
Soil erosion/sedimentation control measures shall be implemented as required to prevent permanent damage to the construction site.
Pipe, fittings and specials shall be carefully examined by the Contractor and BPA for defects just before laying. No pipe or fitting shall be used which is known to be defective. Pipe and fittings shall be thoroughly cleaned before being laid.
Excavation and backfill shall be done as specified in the applicable Item for excavation and backfill and within the measurement limits indicated on the Drawings.
Pipe shall be laid in well compacted bedding material, placed on undisturbed earth or well compacted foundation material.
Pipe shall be uniformly supported throughout its length except for the bell holes required for the proper installation of the joints. The ends or shoulder of each pipe shall abut against the adjacent pipe in such manner that there will be no unevenness along the inverts.
Pipe shall not be laid in water or on frozen trench bottoms or, when in the opinion of the Water Utilities Director, conditions or weather are unsuitable for such work.
Pipe delivered for installation shall be strung so as to minimize the entrance of foreign material. At the end of the day, and at such other times that work is not in progress, all openings in the pipe line shall be plugged. Joints of all pipe in the trench shall be completed before work is stopped. If water accumulates in the trench, the plugs shall remain in place until the trench is dewatered.
Contractor shall set up and use batter boards located at every established grade and line point. A line shall be set parallel to the invert grade line and also parallel to the centerline of the pipe. Not less than three batter boards shall be set before any pipe is placed. A grade stick provided with a bracket on the bottom shall be used to locate it on the line. Method for determining grade shall be approved by the Utilities Director.
In lieu of the above method the Contractor may use a laser beam for establishing line and grade. The methods used shall be as recommended by the manufacturer of the laser equipment and must be satisfactory to the Utilities Director. The laser beam shall be of greater power than 2.5 milliwatts (0.0025). The continual visual check shall be provided by the laser equipment.
The Contractor shall not deviate from the required line or grade without the written consent of the Utilities Director.
No pipe shall be laid until a sufficient length of trench has been properly prepared to permit laying at least one standard length of pipe at one time.
WYES, STACKS, SERVICE SEWER AND RECONNECTIONS:
Y branches, service stacks and house service sewers shall be 6 inches in diameter unless specifically indicated or called for as a different size. Final location, horizontal and/or vertical, shall be responsibility of Contractor.
Each Y branch shall consist of furnishing and placing a Y branch in the trunk or street sewer complete with stop plug, if required, joint materials, excavations, and location marker, if required.
Each service stack shall consist of furnishing and placing a T branch in the main sewer, straight pipe riser, elbow at the top of the stack, stoppers, if required, aggregate and sonotube encasement, additional excavation and location marker. A stack shall be used only when the centerline of the trunk or street sewer is more than four (4) feet below the expected elevation of the house service sewer unless otherwise indicated on the Drawings.
Each standard service sewer shall consist of all earth excavation and backfill, granular bedding material, furnishing and installing all straight and curved pipe at the grade determined by the BPA, (0.62% min.) from the Y branch or service stack to the property line, unless otherwise indicated on the Drawings, or to the point of reconnection to an existing service sewer. Included shall be all joint materials, adaptors, stoppers, location markers, testing and clean-up.
Reconnection of existing service sewers shall consist of locating the existing service sewers, maintaining flow as required, all required earth excavation and backfill, bedding, disconnecting the existing service sewer from the existing trunk or street sewer, removal of existing service sewer as is necessary, securely plugging the discontinued service sewer when required, providing and installing adaptors if connecting different types of pipe, and making a proper connection to the new service sewer.
The location of Y branches and service stacks and the ends of service sewers shall be marked with a one-half inch diameter steel pin, from depth to the surface of ground. If marker is not in paved area, sidewalk area, etc., encase top of marker in concrete 4” diameter by 8” deep, flush with surface.
Where curbs are available, the location of each service sewer shall be marked by a two inch cross cut into the top of the curb on the side of the street to be served by the service sewer.
In all cases, the open ends of Y branches, service stacks and pipes shall be securely closed with carefully fitted plugs, which will not move during field testing, and seal to prevent the entrance of water, earth or other substance into the sewer. Approved plastic plugs may be used if they fit properly into the bell.
ABANDONING EXISTING SEWERS:
Where existing sewer lines are encountered during construction and are indicated on the Drawings or determined by the Village to be abandoned, all broken pipe within the excavation limits of the new construction shall be removed to permit proper placement of bedding and new pipe. At locations where the sewer to be abandoned falls outside of the excavation limits, broken and cracked pipe shall be removed back to a sound joint where a masonry plug shall be constructed of brick and mortar to completely seal the abandoned sewer from the infiltration of soil and water.
Submit shop drawings as required. Included shall be pipe materials, dimensions, joint details and certification that materials conform to the applicable standards.
Upon completion of two manhole spans (approximately 800 feet – 1000 feet) the Contractor shall begin testing the first manhole span (approximately 400 feet – 500 feet). Thereafter, testing shall be performed within 1000 feet of the pipe laying.
Test shall be infiltration, exfiltration or low pressure air test in accordance with the Item for Testing of Pipelines and sewers.
In addition to the leakage test, the Contractor shall furnish all labor, materials and equipment and perform a deflection test using a mandrel whose diameter is equal to 95% of the inside diameter in ASTM D-3034.
Deflection tests shall be made on all sections of sewer.
Deflection of the pipe shall not exceed 5%.
Any section of pipe not meeting the deflection test shall be uncovered and “re-rounded” by re- compacting the bedding material, or by other means as approved by the Utilities Director, and the pipe retested until it meets requirements.