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• <br /> m <br /> 3. Removal of shoring and bracing, and backfilling of voids with satisfactory <br /> materials. <br /> C. 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 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 /> 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 /> 1 <br /> 05/08 02221-9 05-4893 <br />