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_-. _ • i <br />CC&V have proposed not to cap or otherwise protect the waste rocks and spent ore from <br />oxidation by weathering. <br />With part of the leaching data in hand, CC&V propose only to "monitor" water quality in <br />Arequa Gulch. <br />The Division of Minerals and Geology is responsible for controlling the source of acid and <br />toxic forming substances used during or produced by mining. <br />Data in the document under review show that acid is likely to be generated, and dissolved <br />metals are likely to be released, by the simple weathering of disaggregated ore and waste rock. Some <br />of the concentrations of metals and some of the pH values do not comply with currently established <br />water quality standards for Arequa Gulch. <br />If CC&V are allowed to proceed with their proposed waste and spent ore disposal plans, albeit <br />not approved yet by the DMG, it is likely that water discharging from the site will not meet water <br />quality standards. Also, i[ is likely that water which filters into the spent ore and waste rocks will <br />dissolve metals and generate acid that, once discharged to groundwater, will not meet ambient <br />groundwater criteria quality. <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 materials. Capping of the heap and waste rock pile would <br />be acceptable provided the caps are sufficiently impermeable to slow the generation and release of acid <br />and toxic materials to meet water quality compliance criteria. The simple monitoring plan, as <br />proposed in this document under review, is not an acceptable solution to the likely generation of acid <br />and toxic substances. <br />cc: Bruce Humphries <br />Jim Pendleton <br />Carl Mount <br />Gary Curtis <br />Jim Dillie <br />Allen Sorenson <br />Greg Squire <br />