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M . Mechanical connections of the polyethylene pipe to auxiliary equipment such as valves , pumps and tanks shall be through flanged connections which shall consist of the following : 1 . A polyethylene flange shall be thermally butt-fused to the stub end of the pipe . A carbon steel back-up ring shall be used on both sides of the connection prior to thermally butt-fusing the polyethylene flange . 2 . A 316 stainless steel back-up ring shall mate with a 316 stainless steel flange . 3 . Ductile iron back-up rings shall mate with cast iron flanges . N . Flange connections shall be provided with a full-face neoprene gasket. ' O . All PE pipe must be at the temperature of the surrounding soil at the time of backfilling and compaction . P . No single piece of pipe shall be laid unless it is straight. The centerline of the pipe shall not deviate from a straight line drawn between the centers of the openings at the ends of the pipe by more than 1 / 16-in per foot of length . If a piece of pipe fails to meet this requirement check for straightness , it shall be rejected and removed from the site . Laying instructions of the manufacturer shall be explicitly followed . Q . If a defective pipe is discovered after it has been installed , it shall be removed and replaced with a sound pipe in a satisfactory manner at no additional cost to the Owner. All pipe and fittings shall be thoroughly cleaned before installation , shall be kept clean until they are used in the work and when laid , shall conform to the Imes and grades required . R . As soon as the excavation is complete to normal grade of the bottom of the trench , bedding shall be placed , compacted and graded to provide firm , uniform and continuous support for the pipe . Bell holes shall be excavated so that only the barrel of the pipe bears upon the bedding . The pipe shall be laid accurately to the lines and grades indicated on the Drawings . Blocking under the pipe will not be permitted . Bedding shall be placed evenly on each side of the pipe to mid -diameter and hand tools shall be used to force the bedding under the haunches of the pipe and into the bell holes to give firm continuous support for the pipe . Bedding shall then be placed to 12-in above the top of the pipe . The initial 3-ft of backfill above the bedding shall be placed in 1 -ft layers and carefully compacted . Generally the compaction shall be done evenly on each side of the pipe and compaction equipment shall not be operated directly over the pipe until sufficient backfill has been placed to ensure that such compaction equipment will not have a damaging effect on the pipe . Equipment used in compacting the initial 3-ft backfill shall be approved by the pipe manufacturer's representative prior to use . 02627 - 6 F:\Utilities\UTILITY - ENGINEERING\WTP - North RO\N RO Brine Line Discharge - UCP#2208\BID DOCUMENTS North County RO\BID DOCUMENTS\02627 Water Mains High Density Ployethylene .doc