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i <br />Memo to Bruce Humphries <br />-2- <br />October 25, 1990 <br />2. Detoxification of Tailings and Potential Contamination. <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 />r-, ` 4 parts per million upon deposition. That is, cyanide content will be <br />reduced from 60 parts per million to 4 parts Der million before the <br />tailings can leave the enclosed mill facility. Cyanide is a iaturally <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 t>e <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 arty water to <br />the environment. <br />The Mined Land permit requires that air pollution due to blowing tailings <br />be minimized. This will be achieved by Battle Mountain by maintaining <br />the surface moisture of the tailings. Either water trucks or high volume <br />sprinklers will be used to keep the tails moist. <br />3. 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 for 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 site facilities (waste rock facilities, for example) must comply <br />with the WQCC established water quality standards. This is nor-nally <br />achieved through the national pollutant discharge elimination system <br />permitting Drocess administered by the Water Quality Control Division. <br />4. Environmental Ionitoring 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 protected <br />during and after operations. Surface water monitoring points have been <br />established above and below the site to monitor creek flow and water <br />quality. Other environmental monitoring includes slope stabil-ty <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 />for~darded to the P4ined Land Reclamation Division for revie:~ and analysis. <br />1044E/scg <br />