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<br /> <br />COLORADO YAMPA COAL COMPANY <br />CERTIFICATION INSPECTION FOR DRAINAGES <br />DATE OF INSPECTION August 15, 1988 <br />INSPECTION ACTIVITIES <br />o Checked grade and channel dimensions for 225 foot section of <br />Drainage 41 below riprapped upper section. <br />o Checked bedding and riprap placement for upper channel <br />section. <br />o Photographed channel configuration and material placement. <br />FINDINGS <br />o The first 100 foot section checked was at or below the <br />construction grade of 22.8 percent and was within the <br />acceptable grade range (Design gradient is 23.7 percent but a <br />flatter gradient of up to 2.0 percent is acceptable). <br />o The lower 125 foot section checked was flatter than the <br />acceptable minimum grade so the contractor cut approximately <br />0.6 feet over the entire section during the inspection. A <br />recheck of grade indicated an acceptable grade over this <br />section of 22.8 percent. <br />o The bedding and riprap placement for the upper channel section <br />generally looked good with adequate thicknesses, uniform <br />placement, and good gradation. <br />o Two problem areas were noted as follows; <br />1) A section on the west edge of upper channel has <br />predominantly larger rocks with little intermediate fill. <br />This could result in undercutting of the adjacent bank <br />during high flows. <br />