1999-338A - Laserfiche WebLink

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11 r the top of pipe, and fill shall not be dropped directly on the unprotected pipe surface. r (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 t. Engineer or his authorized representative. I (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. i B. SUBSEQUENT BACKFILL 1 j Subsequent backfill is that backfill between the initial backfill and + the finished ground level or bottom of subbase. I . 2) Subsequent backfill material shall be placed full trench width in horizontal layers not exceeding 1.2 inches loose depth and 1 compacted by power -operated tampers, rollers, or vibratory t 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 may be 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 1 112 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 I or Type 3 backfill as determined by the Engineer. 2) All excavated material not suitable for backfill shall be placed on site. at an acceptable location, by Owner, or hauled off the job at the price set forth in the accepted 'Bid Documents. All material that is brought in from other sources for backfill shall be at the price set forth in the Contract. 3) Excavated material to be used for backfill shall be neatly deposited at the sides of the trenches where space is available to protect against caving or sloughing into rhe trench. Where stockpiling of excavated material is required, the Contractor shall coordinate the k 2Q.s 6