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DIVISION OF RECLAMATION, MINING AND SAFETY <br />Department of Natural Resources <br />1313 Sherman St., Room 215 <br />Denver, Colorado 80203 <br />Phone: (303) 866 -3567 <br />FAX: (303) 832 -8106 <br />April 10, 2013 <br />Mr. Tony Tennyson <br />Colowyo Coal Company <br />5731 State Highway 13 <br />Meeker, CO 81641 <br />STATE OF COLORADO <br />COLORADO <br />ID IV I S I O N O F <br />RECLAMATION <br />MINING <br />SAFETY <br />John W. Hickenlooper <br />Governor <br />Mike King <br />Executive Director <br />Loretta E. Pineda <br />Director <br />RE: Colowyo Coal Company, Permit No. C -81 -019, TR -95, Fourth adequacy letter <br />Dear Mr. Tennyson: <br />Regarding your third adequacy letter response (dated March 18, 2013 and received by the <br />Division on March 19, 2013), I have the following comments and questions. The <br />Division's decision on TR -95 is pending answers to several questions (italicized in this <br />letter). The first four headings correspond to the comment numbers in previous adequacy <br />letters. Several items may warrant further discussion via teleconference or a face -to -face <br />meeting. Please contact me regarding this option. <br />COMMENT #1 (from 1/22/2013 letter written by the Division) <br />The Division recognizes that Colowyo is not requesting changes to the curve numbers in <br />the SEDCAD hydrologic model for areas reporting to the Prospect Pond; Colowyo is <br />only requesting changes to curve numbers for other areas of the mine site. In the <br />adequacy response letter of December 13, 2012, Colowyo states that, "The issues <br />encountered within the Prospect Drainage have been unique to the Prospect Drainage and <br />are not applicable across the balance of the mining operation." Please elaborate on what <br />makes Prospect unique. <br />Colowyo 's Response: <br />The Prospect Drainage is unique in that over the past 30 years it has been subjected to <br />two very short duration, extremely intense localized storm events that did not meet the <br />criteria for a 10 year 24 -hour storm event as defined by the SEDCAD program. These <br />events were responsible for offsite impacts from runoff generated from the areas <br />reporting to Prospect Pond. <br />Other drainage basins at Colowyo Mine have been subjected to similar or potentially <br />even more intense short duration storm events in the past and have adequately managed <br />the subsequent runoff without off -site impacts. <br />Division Comment (Fourth Adequacy) <br />This response is adequate. <br />Office of Office of <br />Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines <br />