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-_, <br /> <br />Berhan Keffelew/Posey & York-Fenn re: Cresson leach tests <br />February 23, 1995 <br />Page 2 <br /> <br />1. Ore and waste rock covered under Permit No. M-80-244 have the potential to generete acid <br />and metals if allowed to weather (oxidize) in a manner simulated by the weathering tests. <br />2. Certain action must be taken by the operator to inhibit the generation of acid and toxic <br />materials (dissolved metals) to the extent that release of those materials would violate <br />applicable water quality standards for the receiving streams. <br />We maintain again that leachability data must be evaluated relative to some reasonable measure. <br />CC&V chose to evaluate the data in terms of "Ambient water quality" at Station AG-1 in Arequa <br />Gulch. We have determined that this is not an appropriate measure. The most reasonable one, we <br />believe, is the proposed water quality standards for AG 1.5 and Squaw Gulch, namely, the same as <br />Segment 21 of the Arkansas River. We caution CC&V not to take our evaluation literally in terms <br />of absolute numbers and to recognize that the Division has no jurisdiction over surface water quality <br />standards. <br />The results of the leaching studies confirm that the leachates exceed water quality standards, according <br />to the following: <br />A. Many samples produced leachates with pH below 6.5, which is the regulated lower limit for <br />surface water. <br />B. Many samples produced leachates that had metal concentrations that were higher than would <br />be allowed by surface water quality standards as explained previously. <br />C. The detection limits of several metals were not low enough to detect metals at the levels that <br />would be regulated under the proposed scheme for the CDPS discharge permit. <br />CONCLUSIONS <br />Our conclusion, which is the same as stated in our November 1, 1994 memo, is this: <br />"It is incumbent upon CC&V to prepare for the Division a reclamation plan to prevent the <br />generation and release of acid and toxic material. Capping of the heap and waste rock pile <br />would be acceptable provided the caps are sufficiently impermeable to slow the generation and <br />release of acid and toxic material to meet water quality compliance criteria. The simple <br />monitoring plan, as proposed in the document under review, is not an acceptable solution to <br />the likely generation of acid and toxic substances." <br />CC&V stated in their December 1, 1994, memo: <br />"It makes no sense for CC&V to propose, and bond for, a "cap" in addition to the soil cap that <br />is currently planned and required by the approved permit. The soil cap will certainly reduce <br />infiltration of water through the overburden material and when that soil is relatively saturated <br />