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L. <br />06/07 02221 -9 03 -4197 <br />3. Removal of shoring and bracing, and backfilling of voids with satisfactory <br />materials. <br />mC. <br />Foundation <br />1. A stable foundation must be provided to insure proper line and grade is <br />maintained. Unsuitable foundations must be stabilized at the .engineer's <br />direction. Unsuitable or unstable foundations may be undercut and <br />replaced with a suitable bedding material, placed in 6" lifts. Other <br />methods of stabilization, such as geotextiles may be appropriate based <br />on the engineer's judgment. <br />D. Bedding: <br />1. A stable and uniform bedding shall be provided for the pipe and any <br />protruding features of its joints and /or fittings. The middle of the bedding <br />equal to 1/3 of the O.D. should be loosely placed, with the remainder <br />compacted to a minimum of 90% standard proctor density. Class I, II, and <br />III materials are suitable for use as bedding. <br />E. Haunching <br />1. Proper haunching <br />provides a major portion of the pipes strength and <br />stability therefore care must be exercised in insure placement and <br />compaction of the embedment material in the haunches. For larger <br />diameter pipes ( >30 ") embedment materials should be worked under the <br />haunches by hand. Haunching materials may be Class I, II, or III and <br />must be placed and compacted in 8" maximum lifts, compacted to 90% <br />standard proctor density. <br />06/07 02221 -9 03 -4197 <br />F. Initial Backfill: <br />1. Initial backfill materials are required to a minimum of the pipe diameter for <br />proper structural performance of the pipe. The ASTM specifications <br />extend the initial backfill from the springline to 6 " -12" above the pipe to <br />provide protection for the pipe from construction operations during <br />placement of the final backfill and protect the pipe form stones or cobbles <br />in the final backfill. For proper structural performance of the pipe, the <br />initial backfill need only extend to the pipe diameter. Class I, II, or III <br />materials may be used as initial backfill however: <br />a. Class I materials must be used in wet trenches if Class I bedding <br />and haunching materials are used. <br />b. Class II materials must be compacted in 6" lifts to 90% standard <br />proctor density. <br />C. Class III materials must be compacted in 6" lifts to 90% standard <br />proctor density. <br />06/07 02221 -9 03 -4197 <br />