Furnish all labor, materials, tools, and equipment necessary to lay and join all polyvinylchloride (PVC) pipe and fittings for gravity sanitary sewers as shown or as required to complete the work.
A. 
Polyvinylchloride pipe and fittings shall conform to ASTM Designation D-3034, current edition (SDR-35) or ASTM accordance with ASTM D-1784 (Class 12454-B). Pipe lengths shall be in the longest available.
B. 
Minimum pipe stiffness (F/Y) measured in accordance with ASTM D-2412 shall be a minimum of 45 psi and five-percent deflection.
C. 
Joint seal for PVC pipe (Type SDR-35) shall be oil-resistant compression rings of elastomeric gasket joint material conforming to ASTM D-3212. Fittings shall have push-on, bell and spigot joints compatible with that type of pipe.
D. 
All sanitary sewer force main shall conform to the standards outlined in the Derry Water Main Specifications.
A. 
All pipe or fittings shall be examined before laying, and no piece shall be installed which is found to be defective. Pipe or fittings shall not be dropped. Any damage to the pipe lining or coatings shall be cause for rejection of pipe. All rejected pipe shall be promptly removed from the site and replaced with sound pipe at the contractor's expense. Handling and laying of pipe and fittings shall be in accordance with the manufacturer's instruction.
B. 
Pipe and fittings to be clean; crushed stone; sand.
(1) 
All pipe and fittings shall be thoroughly cleaned before laying, shall be kept clean until they are used in the work and, when laid, shall conform to the lines and grades required. A firm, even bearing throughout the length of the pipe placed in not less than three separate lifts shall be constructed by tamping selected material at the sides of the pipe up to one foot over the top of pipe. Blocking will not be permitted. If any defective pipe is discovered after it has been laid, it shall be removed and replaced with sound pipe in satisfactory manner by the contractor at his own expense.
(2) 
Crushed stone as specified by § A175-22 herein shall be placed six inches below the bottom of the pipe within half the diameter of the pipe being laid through the entire width of the trench.
(3) 
Sand as specified by § A175-22 herein shall be placed 12 inches above the top of the pipe though the entire width of the trench.
C. 
When laying is not in progress, the open ends of the pipe shall be closed by watertight plugs or other approved means. Pipelines shall not be used as conductors for trench drainage during construction.
D. 
Pipe and fittings shall be installed using laser-beam techniques or other approved methods. Care shall be taken to ensure true alignments and gradients as shown on the drawings.
E. 
When pipe is cut in the field, the cut end shall be tapered back approximately 1/8 inch at an angle of 30º with the center line of the pipe with a coarse file or grinder to remove any rough edges which might injure the gasket.
F. 
A tee-wye service lateral shall be installed for each existing building or as directed by the Engineer. The services shall be extended to the edge of the Town right-of-way and constructed to the standards specified in Article V herein (Sewer Services).
G. 
Gravity sewer lines; slopes.
(1) 
Gravity sewer lines shall span a maximum of 500 feet between sewer manholes.
(2) 
Minimum pitch for all sanitary sewer mains shall be as indicated in Table 1.[1]
(3) 
Any deviation in slopes of sewer mains from construction plans must be approved by the Town's Engineer prior to installation.
A. 
Gravity sewers.
(1) 
All gravity sewers shall be low-pressure air tested in conformance with ASTM C-828. The Engineer shall be present during the entire testing period for approval.
(2) 
The sewer line shall be sealed at each end, and one shall have an orifice through which to pass air into the pipe. The pressure gauge will range from zero to five psi with minimum divisions of 0.10 psi. The pipeline under test shall be properly blocked to prevent displacement while the line is under pressure.
(3) 
The line will be allowed to stabilize at four psi for a period of no less than five minutes. After the stabilization period, commence timing with a stop watch. Table 2 shall be used to determine a one-psi drop in pressure.[1] If the actual time lapse is greater than that specified, the section undergoing the test shall have passed. If the line has not passed the test, the contractor, at his own expense, shall make the necessary repairs or replacements required to permanently reduce the leakage to within the specified limits. Testing shall be repeated until the leakage requirements are met.
B. 
All force main sewer shall be pressure tested in conformance with the Town of Derry Water Specifications.
C. 
All gravity sewer pipe shall also be subject to a mandrel deflection test 30 to 60 days after installation of the pipe or after adequate compaction is assured. If the mandrel does not pass through the pipeline, the entire section shall be excavated and relayed and, after backfilling and adequate compaction is assured, the pipeline shall be retested.