§ 3. Part 3—Execution

3.1. Project Conditions.

A. Protection of Water Line.

1. Horizontal Separation. Sewers shall be laid at a minimum at least 10-feet, horizontally, from any existing or proposed water lines or service.

a. Should local conditions prevent a lateral separation of 10-feet, the sewer line shall be constructed of AWWA C900 polyvinyl chloride or Class 52 Ductile Iron pressure pipe.

2. Vertical Separation. Whenever sewers cross under water lines, or services, the sewer shall be laid at such an elevation that the top of the sewer is at least 18-inches below the bottom of the water lines. When the elevation of the sewer cannot be relocated to provide this separation the sewer line shall be constructed of AWWA C900 polyvinyl chloride or Class 52 Ductile Iron pressure pipe for a distance of 10-feet on each side of the water lines.

B. Private Wells. Sewers shall be laid at a minimum at least 50 feet, horizontally, from any existing or proposed private well. Should local conditions prevent a lateral separation of 50-feet, the sewer main shall be constructed of AWWA C900 polyvinyl chloride or Class 52 Ductile Iron pressure pipe from manhole to manhole reach including the service connection pipe.

3.2. Inspection.

A. The contractor shall notify the NSSD 24 hours in advance to make an inspection of the sanitary connection. The inspection(s) will be made prior to backfilling the trench. If more than one inspection is required to be made by the NSSD, the contractor will be required to reimburse the NSSD for the associated costs involved in the re-inspection(s).

B. If during the inspection(s) it is found that the installation of the service connection is not in compliance with these specifications or details, the contractor shall immediately take corrective measures, and the service connection will be re-inspected at the contractor's expense.

3.2. Connections Made at Existing Sewer Main.

A. The contractor shall install a pipe saddle per manufacturer recommendations if a wye does not exist.

3.3. Connections Made at Property Line.

A. The contractor shall connect to the sewer service pipe located at the property line with a flexible coupling.

B. The contractor shall install a clean-out just upstream from the flexible coupling.

3.4. Clean-Outs.

A. Clean-outs shall be installed at the property line, at every fitting over 22½ degrees and at 75-foot intervals up to 150-feet. Service connections which are longer than 150-feet shall have sanitary manholes installed at a locations(s) as directed by the NSSD.

3.5. Excavation and Backfill.

A. The width of the trench shall be held to a minimum consistent with the space required to permit satisfactory jointing of the pipe and tamping of the bedding and backfill material under and around the pipe. In general, the maximum trench width shall be the pipe diameter plus two feet or a minimum width of three feet, whichever is greater. If necessary, sheeting and/or shoring shall be used to prevent overcutting at the level of the top of the pipe and to maintain the trench sides. The trench bottom should be smooth, level and all large stones or rocks lying on or protruding from the trench bottom shall be removed. Over-excavation will be refilled in 6-inch lifts with approved granular material and compacted to 95% maximum density.

B. Where unsuitable material is encountered at the trench bottom, the material shall be excavated to a stable bottom and refilled with compacted bedding material in 6-inch lifts.

C. Backfill from the centerline of the pipe to a height of two feet above the pipe shall be sand blanket material placed evenly the full width of the trench and compacted in 12-inch layers. The remainder of the trench shall be backfilled evenly with suitable (excavated or borrow) backfill material and compacted in 12-inch layers. Cushion and backfill material shall be compacted to 95% maximum density by tamping and compacting in layers (1-foot maximum) to achieve the required compaction.

3.6. Installation of Pipe.

A. Each pipe length shall be inspected for cracks, defects in coating or lining, and any other evidences of unsuitability. Before lowering in place, the pipe shall be struck with a suitable tool to verify its soundness.

B. Pipe shall be laid in the dry and at no time shall water in the trench be permitted to flow into the sewer.

C. The pipe shall then be laid on the trench bedding as shown on the standard trench detail, and the spigot pushed home. Jointing shall be in accordance with the manufacturer's instructions and appropriate ASTM standards, and the contractor shall have on hand for each pipe-laying crew, the necessary tools, gauges, pipe cutters, etc., necessary to install the pipe in a workmanlike manner. Pipe laying shall proceed upgrade with spigot ends pointing in the direction of flow.

D. Blocking under the pipe will not be permitted except where a concrete cradle is proposed, in which case precast concrete blocks shall be used.

E. After the pipe has been set to grade, additional bedding material shall be placed in 6-inch layers up to the spring line of the pipe. Tamping bars shall be carefully employed to assure compaction of the bedding under the lower quadrants of the pipe for the full width of trench excavation.

F. If inspection of the pipe is satisfactory, the contractor may then backfill the remainder of the trench in accordance to the specifications and details.

G. If a trench box is being used and the trench box is below the spring line of the pipe, the trench box shall be lifted vertically, and the stone bedding shall be thoroughly compacted to the trench wall. The trench box shall not be pulled horizontally along the trench.

H. At any time that work is not in progress, the end of the pipe shall be suitability closed to prevent the entry of animals, earth, etc.

I. Unsatisfactory work shall be dug up and re-installed to the satisfactory of the NSSD.

3.7. Recording Location.

A. The contractor shall submit to the NSSD, after completion of the service connection(s), installation of a sketch showing the location of the service connection utilizing distances from permanent structures. The depth at the sewer main property line and at the dwelling unit shall be recorded.