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• <br />COLORADO YAMPA COAL COMPANY <br />CERTIFICATION INSPECTION FOR DRAINAGES <br />DATE OF INSPECTION September 9, 1988 <br />INSPECTION ACTIVITIES <br />o Checked grade and channel dimensions for Drainage 51 <br />o Checked bedding and riprap placement for additional 100' <br />section of Drainage 31-1 <br />FINDINGS <br />o Of the 225' of Drainage 51 which was checked for grade, all <br />but the final 25' was at or below the design grade of 15.7%. <br />During the inspection, the lower 25', which was over-steepened <br />at 17.2%, was regraded and rechecked. Regrading resulted in <br />an acceptable gradient for this section of 15.4%. <br />o The upper key cut for Drainage 51 was moved approximately 50' <br />uphill to provide a better transition to natural ground. <br />o Bedding and riprap placement for the additional 100' section <br />of Drainage 31-1 looks good with adequate thickness, uniform <br />distribution and good gradation. The modified placement <br />methods are resulting in better channel definition, however, <br />previously noted problems in th upper portion of Drainage 31-1 <br />and in Drainage 31-2 remain to be addressed. <br />CORRECTIVE MEASURES NOTED <br />o Work on channel definition for drainaoes 31-1 and 31-2. <br />