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Section 13 <br />Geochemical Data and Analysis <br />• direct contact with soils are appropriate for evaluating possible toxic-forming <br />materials. In addition, the most restrictive (i.e., lowest) RMC for arsenic is based on a <br />worker that might visit the site to perform such activities as control of invasive species <br />and abatement of fire hazards. If this worker is protected, other visitors to the site - <br />campers, ATV riders, surveyors - will also be protected. Based on the BLM land <br />management plan for this area (BLM 1985), future land use for the site is assumed to <br />be mineral development and reclamation, and thus future residents were not <br />evaluated. Based on the above results, the following conclusions are justified: <br />¦ A worker scenario is the most restrictive of applicable exposure scenarios for the <br />Van 4 Mine, and conclusions concerning toxic-forming potential are appropriately <br />based on this receptor <br />¦ Groundwater at the site is present only at a depth that precludes contact for <br />visitors to the site, including campers, ATV riders, surveyors and workers. Thus, <br />RMCs based on direct contact with soil are appropriate for evaluating toxic- <br />forming potential <br />¦ Metals concentrations in development rock are higher than regional background <br />and screening against health-protective criteria is appropriate for evaluation of <br />toxic-forming potential <br />¦ Screening using BLM RMCs and USEPA RSLs indicates that no constituents are <br />. present at concentrations that suggest toxic-forming potential (arsenic is <br />addressed separately below) <br />¦ A site-specific RMC for arsenic, using site-specific exposure considerations and <br />measured arsenic bioavailability, indicate that arsenic concentrations also do not <br />suggest toxic-forming potential. <br />Overall, available data for development rock present at the Van 4 Mine does not <br />suggest significant toxic-forming potential. No restrictions to currently assumed land <br />use appear necessary for protection of human health for future range workers or other <br />future site visitors to the site. <br />It should be noted that risks to miners were not evaluated as part of this assessment <br />because mine safety, including exposure to mine rock and minerals, is regulated by <br />the Mine Safety and Health Administration (MSHA) in accordance with the federal <br />Mine Safety and Health Act of 1977 as amended, and other federal laws and <br />regulations. Denison s mining operations comply with these regulations. <br />Potential Leachate Migration Risk <br />The potential for development rock or ore to form leachate containing metals is <br />dependent on several factors including the following: <br />• ¦ The propensity for the rock to release metals to infiltrating water (leaching). To <br />evaluate this factor, MWMP analyses were conducted on development rock and <br />13-3 <br />7:\64986-Denison Mines\7ask Order 4 - EPP Sunday Mines GroupNan4\Van4\FINAL Repon\FINAL - Environmental Protection Plan Van4.doc