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<br />Memo to Bruce Humphries <br />-2- <br />Detoxification of Tailings and Potential Contamination. <br />October 25, 1990 <br />The Mined Land Reclamation Board has approved a tailings disposal plan <br />which clearly states that cyanide content of the tailings will not exceed <br />4 parts per million upon deposition. That is, cyanide content will be <br />reduced from 60 parts per million to 4 parts per million befcre the <br />tailings can leave the enclosed mill facility. Cyanide is a naturally <br />unstable compound, and is readily decomposed in sunlight. Upon <br />deposition, the cyanide content is expected to be reduced even further <br />due to natural degredation. <br />Water pollution will not occur as the tailings facility will be <br />underlined by compacted earth and impermeable plastic. The tailings <br />material will consolidate over time from the bottom up to form another <br />liner system. The tailings facility is designed to contain all cyanide <br />solutions on site as well as rainfall from a major storm event, known as <br />a probable maximum precipitation event, without discharging any water to <br />the envi ronment. <br />The Mined Land permit requires that air pollution due to blowing tailings <br />be minimized. This will be achieved by Battle Mountain by ma~'ntaining <br />the surface moisture of the tailings. Either water trucks or high volume <br />sprinklers will be used to keep the tails moist. <br />Applicability of Drinking Water Laws <br />The Colorado Department of Health establishes receiving stream water <br />quality standards. The Department of Health, Water Quality Control <br />Commission has classified Rito Seco as a Class 2 cold water aquatic life <br />stream. Generally, the water quality standards established fcr this <br />stream category are more stringent than drinking water standards. This <br />generality is true for Rito Seco. <br />The tailings disposal facility is a non-discharging structure, so no <br />impacts to any water supply are anticipated. Water discharges from other <br />mine sits facilities (waste rock facilities, for example) must comply <br />with the WQCC established water quality standards. This is normally <br />achieved through the national pollutant discharge elimination system <br />permitting process administered by the Water Quality Control Division. <br />4. Environmental Monitoring Systems <br />An extensive monitoring program has been required of Battle Mountain <br />Resources to ensure environmental protection. Water wells wil~ provide <br />assurance that the quantity and quality of ground water is prottected <br />during and after operations. Surface water monitoring points gave been <br />established above and below the site to monitor creek flow and water <br />quality. Other environmental monitoring includes slope stability <br />measurements to ensure long-term integrity of the tailings disposal <br />facility embankment, tailings disposal facility liner monitoring, and <br />observation of the tailings material itself. All information collected is <br />forwarded to the Mined Land Reclamation Division for review and analysis. <br /> <br />1044E/scg <br />