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3.3 Installation of Watermain <br />Excavate trench to a depth adequate to provide 7.5 feet of cover above <br />watermain. Compact bottom of trench to 95% of ASTM D698, and place <br />specified aggregate bedding material as indicated on the drawings. Place <br />water pipe at bottom of trench and backfill trench in layers using <br />aggregate bedding material and material from excavation. Each layer of <br />backfill shall not exceed 12 inches in thickness and shall be compacted to <br />same density as bottom of trench. Test all piping for leakage. <br />3.4 Installation of Subdrain System <br />Subdrain system shall be installed by excavating the trench, installing the <br />filter fabric and placing about three inches of course filter aggregate in <br />the trench. The perforated subdrain shall be inserted in the trench, <br />additional coarse filter aggregate placed and the filter fabric overlapped <br />about eight inches on the top of the trench. The subdrain shall extend <br />over to the railroad spur ditch and daylight in the ditch slope. <br />12 <br />