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R 21NCORPORATED <br />ENVIRONMENTAL AND ENGINEERING SERVICES <br />---------------- -------------------------- <br />STRATECICALLY POSITIONED-TECHNICALLY PREPARED <br />June 1, 2011 <br />Mr. Wallace Erickson <br />Department of Natural Resources <br />Division of Reclamation Mining and Safety <br />1313 Sherman Street, Suite 215 <br />Denver, Colorado 80203 <br />GEORGE M.L. ROBINSON.P.G. <br />1. ERICH RALIBERY.E. <br />RECEIV60 <br />JUN 0B 7011 <br />Di, ion c, Reciarriaticn, <br />Mining nd Saf?-% <br />Re: Geotechnical Responses to Cazier's Comments <br />March 11, 2011 Memorandum <br />Wildcat Mining Corporation- May Day Idaho Mine Complex; DRMS File No. M-1981-185; <br />Conversion Application CN-1 <br />Dear Mr. Erickson, <br />The following responds to Mr. Cazier's geotechnical comments related to Wildcat Mining <br />Corporation-May Day Idaho Mine Complex. <br />Comment <br />1. On page 2 of the GSE, the application states, "There are no geologic hazards for slopes <br />greater than 1.5:1 on the May Day Idaho Mine Complex. Any slopes steeper than 1.5:1 will <br />be evaluated for stability. " The Division cannot accept 1.5H.•1 V slopes to be stable without <br />demonstration, especially given the first quarter, 2010 slope failure at May Day No. 1 <br />involving the collapsed portal discussed in the paragraph immediately below the referenced <br />quote. The Division will require a slope stability demonstration for any facilities that are <br />associated with slopes steeper than 2H.- 1 V and natural ground disturbance. <br />Response #1 <br />The GSE has been revised to indicate that constructed slopes steeper than 2:1 will or have <br />been evaluated for stability. <br />Comment <br />2. In the last paragraph on page 2 of the GSE, there is a wide range for the allowable bearing <br />capacity of the soil (4,500 to 16,000 lbs/f?). The applicant will need to demonstrate the <br />bearing capacity of the soil that will be supporting the steel sets. The paragraph also <br />suggests the soil being supported by the steel sets will be compacted (6 feet of compacted soil <br />for the 4,500 lbs/f? bearing capacity vs. 20 feet of compacted soil for the 16, 000 lbs/f? <br />"Strategically Positioned - Technically Prepared" <br />5555 DTC Parkway Suite A-4000, Greenwood Village, Colorado 80111 <br />Phone: (303) 832-7664 Fax: (303) 832-7469 <br />... is F