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and backfill in accordance with the requirements for Class B Bedding . All unsuitable material shall be disposed of by the Contractor. 8 ) PIPE TRENCH BACKFILL A) INITIAL BACKFILL 1 ) Initial backfill shall be placed as soon as possible after laying the pipe and shall maintain a pace with the pipe laying so that no more than fine pipe joints separate laying and backfilling operations . Initial back fill shall include all haunching and backfill from the top of the bedding to a compacted depth of twelve inches over the pipe . All haunching and backfilling shall be done in the dry . 2) Initial backfill shall be done as specified below: (A) Haunching of the pipe shall be by hand , placement and compaction of material in maximum 4 inch layers from the bottom of the trench to the springline of the pipe , taking care to fill all voids below and around the pipe . Backfilling shall be carefully continued in layers not exceeding 6 inches in thickness for the full trench width until the compacted fill is 12 inches above the top of the pipe . ( B) During initial backfilling the fill shall be deposited evenly along both sides of the pipe from a height not to exceed 2 feet above the top of pipe , and fill shall not be dropped directly on the unprotected pipe surface . ( C ) Where thrust blocks , encasement , or other cast- in-place concrete items are below grade , no backfilling shall start until the specific items have been inspected and approved by the Engineer or his authorized representative . ( D) The backfill to one foot above the top of the utility shall be thoroughly compacted with curved end tamping bars under and on each side of the pipe and flat tamped between the pipe and trench wall and shall be completed before the remainder of the trench is backfilled . Initial backfill shall be compacted to 100 percent of maximum density as determined by AASHTO T- 180 . No subsequent backfill will be permitted until the initial backfill has been accepted by the Engineer or his authorized representative . B) SUBSEQUENT BACKFILL 1 ) Subsequent backfill is that backfill between the initial backfill and the finished ground level or bottom of subbase . 2 ) Subsequent backfill material shall be placed full trench width in horizontal layers not exceeding 12 inches loose depth and compacted by power-operated tampers , rollers , or vibratory equipment to a density equal to 98 percent of the maximum density as determined by AASHTO T- 180 for pipe placed under and adjacent to roadways or paved surfaces , and 95 percent under areas where no pavement is to be constructed and vehicular traffic is not to pass over the pipe . Each layer shall be compacted to the specified density prior to placing subsequent layers . The thickness of the loose layer maybe increased when in - place density tests show that the specified density can be obtained . C) BACKFILL MATERIAL 1 ) Type 2 material shall be used for initial backfill and subsequent backfill with the following conditions : Initial backfill shall be predominately sandy material free from rock or stone greater than 1 1 /2 inches diameter, and the maximum allowable dimension of a stone or rock fragment for subsequent backfill shall be 6 inches . If in the opinion of the Engineer the Type 2 material will not provide adequate and uniform support for load distribution to the pipe , the Contractor shall obtain and place either Type 1 or Type 3 backfill as determined by the Engineer. D-3-4