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~: ~ ~ -~ •~1 iiiiiiiiiii iii iiii i • t, / 999 STATE OF COLORADO DIVISION OF MINERALS AND GEOLOGY Deparlmenl of Natural Resources 1313 Sherman 51., Room 215 rr Denver, Colorado 80203 ~ ~ Phone: 1]03) 866-3567 II FAX: 13031832-8106 DEPARTMENT OF NATURAL RESOURCES Roy Romer Governor DATE: July 11, 1995 lames 5. Lochhead Ezecwive Director michael B. Long TO• Berhan Keffelew Division Direcor FROM: Harry Posey RE: Geochemical review: June 5, 1995 letter from CC&V to B. Keffelew regarding "Contact Tests;" CC&V, Cresson Project, Permit No. M-80-244. METHOD OF EVALUATION: General: Based on the proposed uses of the materials discussed, it is evident that waters which pass through the waste rock will discharge to surface water in some cases and to groundwater in others. On that basis, we compared the "contact test" results from the Pad 2 material to in-place surface water standards (for potential surface water discharges) and to a combination of ambient groundwater measurements and drinking water standards (for potential discharges to groundwater). This comparison was direct; it does not consider any potential dilution, attenuation effects on the discharges themselves, or transit time effects between the discharge points and points of compliance. Measurements or model calculations that factor in attenuation, dilution, metals precipitation, or transit time, if they are to be considered, should be submitted by the Operators. Surface Water Standards: The operator has submitted to the WQCC proposed standards and proposed interim standards for surface waters for Arequa Gulch and Squaw Gulch. WQCD has stated that the proposed standards are not acceptable to them. They indicated further that the standards which apply presently to Arequa and Squaw Gulches are those in place for Segment 21 of Cripple Creek and its tributaries. Given this illustration based upon the present standards. Groundwater Standards: The Division has established that discharges to groundwater at the Cresson operation must meet the higher of either the Table Value Drinking Water Standards or the ambient groundwater quality as measured at the Carlton Tunnel discharge.