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III IIIIIIIIIIIIIIII <br />999 <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Natural Resources <br />1313 Sherman SI., Room 215 <br />Denver, CO 80207 <br />Phone: 1303) 866-3567 <br />FAX:13031832-8106 <br />November 5, 1993 <br />Mr. Murari P. Shrestha <br />Assistant Manager of Engineering <br />Western Fuels - Utah <br />405 Urban Street <br />Suite 305 <br />Lakewood, Colorado 80228 <br />RE: Minor Revision MR-86 <br />Small Area Exemption - Road Base Material <br />Deserado Mine (C-81-018) <br />Dear Murari: <br />pF COQ <br />4:4 <br />~e~~ `~ <br />rB ]6 ~ <br />Roy Romer <br />Governor <br />Michael B. Long <br />Dmnion Director <br />The Division has reviewed your application for a minor revision <br />allowing a small area exemption for a roadbase material stockpile <br />at the Deserado Mine. As a result of the review, the following <br />adequacy concerns are noted: <br />1) The calculations indicate that the precipitation depth <br />for a 10 year - 24 hour event is 1.4 inches. The <br />Division could not verify this depth in referring to the <br />NOAA Atlas 2, Volume III. It appears that Western Fuels <br />has used the precipitation depth value for May-October, <br />however the design should have been based on annual <br />precipitaiton data for the entire year. Please provide <br />documentation that at depth of 1.4 inches is appropriate, <br />or revise the storm estimate to 1.6 inches as shown in <br />the NOAA Atlas. <br />2) Using a precipitation depth of 1.6 inches for a 10 year - <br />24 hour storm, the Division calculated volume <br />requirements for the storage facility. The volumes <br />calculated are 72.9 cubic feet for sediment and 2613.6 <br />cubic feet for runoff, or a total of 2686.5 cubic feet of <br />required storage. Therefore, the proposed storage volume <br />of 2000 cubic feet is not adequate. <br />3) Three copies of all maps are required for submittal of a <br />minor revision. Only two copies of Map 146 were <br />submitted. Please submit another copy of Map 146. <br />In the future, if three copies of all maps and drawings <br />