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600-4 I'; I, IJ I; II Ii Ii; I I . I .1 I I I t. I ,I -J .Wben'excavatio" is encountered that is unsuitable for backfill, it shall be removed as directed by the ENGINEER. 603.200 Preparation of Soil Durinq Pipe ~vin9 At the time of pipe placement, the bedding conditions shall be such as to provide uniform and continuous support for the pipe between bell holes. Bell holes shall be excavated as necessary to make the joint connections, but they shall be no larqer than would be adequate. No pipe material shall be laid in water nor when the trench or bedding conditions are otherwise unsuitable or improper. If trench bottom conditions are encountered which appear to require stabilization, the ENGINEER shall be informed. The trench conditions shall be examined by the ENGINEER to determine the nature of such inst.ability, employing the services of a testing laboratory if necessary. If it is determined that the trench bottom cannot support the pipe, D. further depth and/or width shall be excavated and refilled to the pipe foundation grade with granular foundation material and thoroughly compacted. If the examination by the ENGINEER reveals that the afore- described conditions are caused by the CONTRACTORIS manipulation of the soils in the presence of excessive moisture, or lack of proper dewatering, the CONTRACTOR shall take such steps as are necessary to stabilize the trench bot.tom including the use of pipe support material, and improved dewatering methods. In such case, the cost of measure necessary shall be borne by the CONTRACTOR. " When the bottom of the trench consists of, a material suitable to properly support the pipe the following methods of bedding shall apply: . (1) , (2) (3) Granular bedding material will be placed below the midpoint of the 'pipe, prior to pipe installation, to facilitate proper shaping and achieve uniform pipe support, using hand compaction methods. Granular backfill material at pipe zone shall be free from rook, boulders or other unsuitable sUbstances and shall be deposited into the trench simultaneously on both sides of pipe for the full width of the trench in six-inch lifts thoroughly compacted to a minimum elevation, ,of one foot above the top of the pipe. Compaction shall be accom- plished by mechanical ta1llpinq. The qranular backfill material shall be placed to the top of the trench of street subgrade elevation in level, successive layers, having a thickness of not greater than 12 inohes. Each successive layer shall be thoroughly compacted as specified prior to' the placement or addi- tional layers. If the specified aompaction is not being