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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 <br />Phone: (303) 866-3567 <br />FAX: (303) 832-8106 <br />MEMO <br />COLORADO <br />D I V I S 10 N O F <br />RECLAMATION <br />MINING <br />SAFETY <br />Date: December 11, 2008 <br />Ritter, <br />nor Jr. <br />Golve <br /> Harris D. Sherman <br />To: File Executive Director <br /> West Elk Mine (C-80-007) Ronald W. Cattany <br /> TR-115 Division Director <br /> Natural Resource Trustee <br />From: Tom Kaldenbach <br />Re: Summary of Final Adequacy Review <br />I have reviewed the mine operator's SEDCAD inputs for reasonableness, including: drainage <br />areas, structure routing, slope magnitudes, slope lengths, particle size distributions, design storm <br />rainfall depths, LS factors, K factors, and runoff curve numbers. I verified the inflow volumes for <br />each pond for 10-year and 25-year storms using the Rational method in the attached spreadsheet <br />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 more than <br />three times larger than the calculated 10-year storm inflow); therefore, discharges are not <br />likely to exceed the 50 ml/l discharge limitation. <br />c) Pond discharges will have adequate freeboard during 25-year storms (minimum 1 foot <br />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 been <br />received. <br />DRMS has prepared the attached reclamation cost estimate for TR-115. The estimate indicates a reduction of <br />direct reclamation costs of $239,567. An estimated 97% of the reduction results from lower unit costs for <br />culvert reclamation in the current DRMS cost estimating system (see attached Analysis of Cost Reduction), <br />compared to the last full reclamation cost estimate completed in Permit Renewal RN-5. The operator's <br />representative explained to me on the phone today that, rather than go through the cost adjustment process now <br />(which has a 30-day comment period), the preference would be to account for the cost reduction in the updated <br />full cost estimate that is in preparation in the Midterm Review that will be completed in early 2009. <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