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~ III IIIIIIIIIIIII III r <br />511~TE OF COLORADO <br />Roy Romer, Governor <br />DEPARTMENT OF NATURAL RESOURCES <br />MINED LAND RECLAMATION DIVISION <br />FRED R. BANTA, DlreCtor <br />April 6, 1989 <br />Mr. Mark Korb <br />Korb and Carroll <br />106 East Oak Street <br />Fort Collins, Colorado 80524 <br />Subject: Transmittal of Inspection Report, <br />Grassy Gap Mine, File ND. C-81-039 <br />Dear Mr. Korb: <br />I am enclosing the inspection report prepared during the last week of March. <br />I enjoyed meeting you this week and feel that we had a fruitful discussion. <br />Please inform Mr. Sherman that I have reviewed the drainage design <br />calculations for Pond 005, prepared by Hydro-Triad on October 26, 1984. These <br />included the design fora 4" orifice one foot above the pond's floor. The <br />calculations appeared to be appropriate and allowed adequate volume and <br />detention time for the 10-year, 24-hour precipitation event. I then checked <br />the sediment generation calculations with USLE and found that the pond would <br />need to be cleaned out once every two years, which was inherent within the <br />pond's design criteria. The cover letter from Hydro-Triad did reference a <br />half round CMP baffle around the orifice. I recommend that Mr. Sherman clean <br />out the pond and confirm that it is configured according to design. <br />Sincerely, <br />~,~ ~ <br />Catherine W. Begej <br />Reclamation Specialist <br />CWB/scg <br />Enclosure(s) <br />5019E <br />215 Centennial Building, 1313 Sherman Street Denver, Colorado 80203-2273 Tel. (303) 866-3567 <br />