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STATE OF COLORADO <br />DIVISION OF RECLAMATION, MINING AND SAFETY <br />Department of Natural Resources <br />1313 Sherman St., Room 215 <br />Denver, Colorado 80203 C O L O RA D O <br /> <br />Phone: (303) 866-3567 DIVISION O F <br />RECLAMATION <br />FAX: (303) 832-8106 MIN ING <br /> <br /> SAFETY <br />MEMO <br /> Bill Ritter, Jr. <br />Date: December 5, 2008 Governor <br /> Harris D. Sherman <br /> Executive Director <br />TO: File <br /> Ronald W. Cattany <br />West Elk Mine (C-80-007) Division Director <br />TR-115 Natural Resource Trustee <br />From: Tom Kaldenbach <br />Re: Summary of Review <br />I have reviewed the mine operator's SEDCAD inputs for reasonableness, including: <br />drainage areas, structure routing, slope magnitudes, slope lengths, particle size <br />distributions, design storm rainfall depths, LS factors, K factors, and runoff curve <br />numbers. I verified the inflow volumes for each pond for 10-year and 25-year storms <br />using the Rational method in the attached spreadsheet calculation. <br />My review found: <br />a) All SEDCAD input values appear reasonable. <br />b) The ponds appear capable of containing the 10-year storm runoff (each pond is <br />more than three times larger than the calculated 10-year storm inflow); therefore, <br />discharges are not likely to exceed the 50 ml/l discharge limitation. <br />c) Pond discharges will have adequate freeboard during 25-year storms (minimum 1 <br />foot between emergency spillway water level and top of embankment). <br />d) Ditches and culverts appear adequately sized for 10-year peak discharge. <br />e) Ditches are adequately lined for preventing excessive erosion in a 10-year storm. <br />The mine operator's notice was published on November 12, 2008. No comments have <br />been received. <br />DRMS is preparing a reclamation cost estimate for TR-115. <br />cc: Dan Hernandez, DRMS <br />Ryan Sweetwood, MCC <br />Office of Office of <br />Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines