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.~ COL®1~~-DO Richard D. Lamm Governor December 19, 1985 • OF•C ~Cf' ~ - Q'.% y ~• F.. , , ~-~:~ d ~ ~~. ~'r-. '1 . O DEF~ARTMENT 1r t,n~pur" •1826 III NIIIIIIIIIIIIIII ~' 999 L 12 ~ v v v /~1 s~~~~ OF HEi4LTH Thomas M. Vernon, M.D. Executive Director RECEIVECi 4tr. Tim Smith Director of Environmental Affairs Cotter Corporation 9305 West Alameda Parkway Suite 201 Iakewood, CO 80226 RE: Waste Rock Pile Study Cotter Schwartzwalder Mine CDPS N0: CO-0001244 Jefferson County Dear Mr. Smith: aEC zs ~ Mql® LAND RECLAMATi010 ri010. D~• 01 Ntprill ~01MCtlS This letter is to keep you apprised of the results of this Division's review of the Waste Rock Pile Study submitted by the Cotter Corporation .for the Schwattzwalder Mine. I apologize for the delay in relaying this :Lnformation. The Division reviewed the study as it related to surface xater impacts ae well as groundwater impacts. In our evaluation we conclude that the west pile and most likely the east pile could constitute sources of pollution to the groundwater system adjacent to Ralston Creek and that impact to Ralston Creek may also be occurring. In support of this contention it was noted that several studies harve been performed in the past in the study area of Ralston Creek and the existence of "highly mineralized soil" (as the Cotter report suggests) has not been brought forth. Along with this, other wells drilled in the area (Geo-Hydro Consultants Inc., 1982), do not show the existence of mineralized water associated with "highly mineralized soil." Two of the wells drilled showed relatively good water while a third well, located down gradient of the oresorter, showed elevated levels of some parameters. It was concluded that there is no conclusive evidence of naturally occurring "highly mineralized soil" eziating along Ralston Creek. The only other ezplanatioa for the elevated levels of several metals and sulfate in the groundwater would be the waste rock pile or in the case of the Geo-Hydro well, the ore sorter or waste ponds could also be impacting the groundwater system. It was further noted. in our evaluation, that on page 4 of the report a distinction is made betweea the waste material that is deposited oin the east pile and that which la deposited on the west pile. This information appears to indicate that the pollution potential from the east pile Sa greater, since oresorter reject and ore bearing materials are deposited on the east pile. However, the study focused on the west pile and may not be representative of groundwater conditions at the east pile.