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~~ iii iiiiiiiiniiiiii 999 STATE OF COLORADO DIVISION OF MINERALS AND GEOLOGY Department of Natural Resources 1 J 13 Sherman 51 , Roum ? 15 Denvcr, Colorado 8020] Phone: 13031 866-3567 fAX:13031 8J2 8106 December 20, 1995 Post-if Fax Note 7671 Date ~ z. ZC-/S Pages To From. /C.K ~~QKO/L- Co./Deft ~~ 1 Co. I~ Phone N Phone p Fax K ~ ~ `~ F~ Fax N ~~ ~~~~~ DEPARTMENT OF NATURAL RESOURCES Roy Romer ~~~~ lames S. Lochhead Mr. Don A. Holmer Execmive Dirtttor Colorado Department of Public Michael B. Long Health and the Environment Division Director Water Quality Control Division 4300 Cherry Creek Drive South Denver, CO 80222-1530 RE: Mill Tailing Leachate Study, Homestake Mining Company, Bulldog Mine, Reclamation Permit No. M-77-215, CDPS Permit No. CO-710 Dear Don, I have enclosed the final report, minus appendices, from a spent ore study conducted on samples collected at several mine sites throughout the State. The sample designated as M-77-215-L is a tailing sample collected from the lower tailing impoundment at the Bulldog Mine, and the sample designated as M-77-215-U is a tailing sample collected from the upper tailing impoundment. The upper tailing impoundment is tributary to segment 7 of the Rio Grande Basin, and the lower tailing impoundment is tributary to segment 2 of the Rio Grande Basin. Both of the tailing dams have been breached, and the impoundments are free draining. The lower tailing are being revegetated directly, i.e., no topsoil, overburden, or other capping material has been applied. The upper tailing were capped with varying thicknesses of overburden and waste rock in order to direct runoff to the dam breach. The capping material in the upper pond is being revegetated. During operations at the Bulldog Mine and Mill, tailing were used as backfill in the underground stopes. These stopes were subsequently flooded when the mine dewatering pumps were removed. Any discharge to surface water from the flooded mine pool would likely report to Windy Gulch (Rio Grande:Segment 7) or to Rat or Miners Creeks (Rio Grande:Segment 2). In accordance with direction from the Mined Land Reclamation Board, the Division of Minerals and Geology will not be investigating potential impacts to ground water that may be caused by the underground disposal of mill tailing or other underground mining activities. Neither will we be addressing the potential for surface water impacts that may be caused by runoff from the surface tailing impoundments. We will be investigating the potential for ground water impacts that may. be caused by the mill tailing disposed of in the surface tailing impoundments. In order to facilitate my review of the existing and future data, could you please