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• • iii iiiiiiiiiiiiiiii STATE OF COLORADO DIVISION OF MINERALS AND GEOLOGY Depanmenl of NaWral Resources ~~~~~ 1313 Sherman St., Room 215 Denver, Colorado 80203 Phone: 13031 &6h-3557 FAx: 13031 832-8106 DEPARTMENT OF NATURAL DATE: July 25, 1994 ~SQURCES TO: Berhan Keffelew, Bruce Humphries Roy Romer Governor FROM: Harty Posey Izmes 5. Lochhead Executive Director RE: Review: Completion o Water Quali ty Assessment Addendum, Iro~IFA]cagl Lonti Tailing Material; C sson Project, Permit No. M-80-244 Division Dnenor Having reviewed CC&V's comments of July 20, 1994, I have the following observations. (NOTE: John Hardaway's memo was sent via fax on Jan 20, even though the FAX date indicates Jan 03 'O1). The 10 percent figure and the 14 gpm figure have been explained adequately and I accept the explanations to be sufficiently realistic and environmentally consertavie to be acceptable to the Division. The 7343 gpm figure was not explained, but 2 understand where it was derived from and accept the figure. (The background leading up to this situation may be found in the record.) Please bear in mind that the provisions described apply only to that area of the clay liner beneath which there will be an artificial liner. The area outside that, where clay liner will rest directly on bedrock, remains to be tested. Regarding the plans for leachate quality testing, I cannot agree completely with CC6V's assessment. Even though the local groundwater has not been classified by the DPHE, CC&V would not under any circumstance be allowed to degrade the water quality in any amount above the present conditions. As 2 understand the groundwater regulations and the requirements of SB-181, given that there is certain to be some recharge of Arequa Gulch to the groundwater, albeit even a small amount, that discharge will have to meet the current groundwater conditions. Provided that is the case, then CC&V will need to demonstrate, through the cell testing (or other testing) that is now in progress, that the quality of the groundwater will not be degraded. This brings up a dilemma: if the groundwater is not classified, and if discharges are required to meet ambient conditions, that means that no metal or other regulatable material can be discharged to groundwater in quantities exceeding the present groundwater quality. It is apparent from previous testing that various metals are present and mobile in the liner material, and I would predict that the cell tests may not meet our specifications. 2 would like to discuss this with you before we go much further with this situation. cc: Jim Pendleton Carl Mount