1999-06-11_HYDROLOGY - M1984049 - Laserfiche WebLink

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• III Illlllllllllllll 5TATE OF COLOMDO DIVISION OF MINERALS AND GEOLOGY Department of Natural Resources 1313 Sherman St.,Room 215 Denver,Colorado 80203 D I V I S I O N O F Phone:(303)866-3567 M I N E R A L S FAX:(303)832-8106 & GEOLOGY RECLAMATION MINING-SAFETY Date: June 11, 1999 Bill Owens Governor To: Wally H. Erickson Greg E.Watcher Executive Director From: Harry H. Posey Michael Long Division Director Subject: Monitoring parameter changes; Howardsville Mill; M-84-049. This letter reviews your April 12, 1999 letter from Jerry Sandell, Court Appointed Receiver for Tusco, Inc., Howardsville Mill, and recalls our conversation regarding same. Mr. Sandell proposes to reduce ground and surface water monitoring parameters at Howardsville. With some exceptions, I concur with his recommended parameters list. The attached table compares the analytical parameters already measured to those proposed by Tusco and bears a list of recommended parameters. If the recommended list seem inadequate in your view, please discuss with me further. The table of ground and surface water analyses which you prepared reveals some interesting points about the hydrologic system at Howardsville. Several wide geochemical variations cannot be ascribed to seasonal fluctuations alone. Rather, they seem to reflect a mix of physical and chemical conditions including changes in site conditions that took place during sampling. Changing site conditions and consequent fluctuations in groundwater composition are related most probably to (a) disturbances in groundwater chemistry through excavation of pre-law tailings by Sunnyside Gold Corporation; (b) inhomogeneous contact between groundwater, waste rock and tailings of different compositions along discrete flow paths; (c) surface water discharges from the Sunnyside disturbance; and (d) chemical changes, including manganese mobilization, caused by interaction with low Eh, neutral pH, low carbonate waters in the wetlands. All combined, the significant variations in local geochemistry and groundwater flow make it impossible to define the background conditions with any reliability. Thus, it will be challenging, if not impossible, to define background conditions. Short of having the operator start over with the monitoring program, I believe DMG is obligated to make the best of the highly variable system. To that end, I would agree with your recommendation that the operator monitor for a short list of parameters for three more periods. The Operator's proposed twice-yearly sampling should be adequate. Once the background situation is better defined, the short list of parameters may be shortened even further to monitor only for evidence of contamination related to future operations.