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} . _ ~ III IIIIIIIIIIIIIIII ~ SHEPHERD MILLER September 22, 1997 Mr. Alan D. Cox Corporate Manager, Environmental Affairs Homestake Mining Company of California 650 California Street San Francisco, CA 94108-2788 ~F~EI~fED OCT 2 7 1997 Division of ~,~~ne~rs ~, uec'~O~Y SMI #17-314 Subject: Upper and Lower Tailings Ponds at the Bulldog Mine, Creede, Colorado Deaz Alan: This letter provides a discussion about the issues raised by the Colorado Division of Minerals and Geology (DMG) (Dr. Harry Posey) concenung the evaluation of the Upper and Lower Tailings Ponds at the Bulldog Mine, Creede, Colorado. This evaluation was conducted for Homestake Mining Company (HMC) by Shepherd Miller, Inc. (SMI) and documented in the January 1997 SMI report. The DMG issues were documented in a September 16, 1997 letter from Allen Sorenson to HMC. Attached to the September 16 DMG letter is a revised memo from Dr. Harry Posey to Allen Sorenson dated September 9. DISCUSSION OF ISSUES The September 16 DMG letter concludes that the magnitude of potential seepage impacts to ground water from Bulldog Tailings Impoundments will be minimal. Release of HMC by DMG from further responsibility under the ground water protection regulations of the Colorado Mined Land Reclamation Board will be finalized contingent upon addressing the issues in the September 9 revised memo. In summary of the September 9 revised memo, Dr. Posey agrees with SMI that the mineralogy, per se, indicates a potential for generation of acidic water. However, Dr. Posey is not fully convinced, from the oxygen consumption and petrographic data presented in the SMI report, that the oxidation of sulfides is not occurring within the impoundments. Dr. Posey is also concerned Envrsonmrntal d' Enginrrring Conn/tantf 3801 Automation Wav, Suite 100 Fort Collins, CO 80525 p~l].]I~Wmgnp tlrc Phone: (970) 223-9600 Faz: (970) 223J171