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manganese, and zinc in the adit discharge constitute a potential hazard. There are <br /> currently no barriers to access to these materials for recreational users of the property. <br /> There is no current or planned future residential use of the property. <br /> Consistent with the future land use as a recreational and natural-preservation area, <br /> concentrations in source materials(solid and aqueous)can be compared to the Risk <br /> Management Criteria(RMC)developed by the Bureau of Land Management(BLM)for <br /> metals at BLM mining sites(Ford, 1996). The RMC benchmarks are shown along with <br /> the analytical results in Table 2. The RMC benchmarks have some uncertainties <br /> associated with the exposure factors and extrapolations to additional species. Based on <br /> these uncertainties, Ford(1996)suggests the following guidelines when evaluating risks <br /> by comparison to the RMC benchmarks: <br /> Less than or equal to the benchmark concentration: Low Risk <br /> • >1 to 10 times the benchmark: Moderate Risk <br /> >10 to 100 times the benchmark: High Risk <br /> • >100 times the benchmark: Extremely High Risk <br /> Concentrations in source materials exceed the BLM screening benchmarks for wildlife <br /> and certain recreational uses. <br /> 8.1 Wildlife and Livestock <br /> Potential risks to wildlife and livestock were assessed by comparing measured <br /> concentrations in source materials to the median RMC benchmark value presented in <br /> Ford(1996). The BLM publication does not assess potential risks to wildlife and <br /> livestock from aqueous discharges such as the flowing adit at the site. Therefore,the <br /> streamlined risk assessment for wildlife and livestock is focused on the waste rock and <br /> tailings piles at the site. <br /> Concentrations of arsenic and copper measured in waste-rock materials indicate a <br /> moderate risk to wildlife and livestock. Concentrations of cadmium, lead,and zinc in <br /> waste-rock materials are within the range of high risk when compared to the median <br /> RMC benchmarks(CDPHE, 2002). <br /> The majority of the fine-grained tailings at the base of the former milt area were covered <br /> in a previous remedial action conducted by B&B Mines, Inc. However,some tailings <br /> remain exposed around the edge of the cover. The reported concentrations of copper <br /> and lead present in these exposed fine-grained tailings indicate an extremely high risk to <br /> wildlife and livestock when compared to the median RMC benchmarks. Cadmium and <br /> zinc concentrations in the exposed tailings indicate high risk to wildlife and livestock <br /> (CDPHE,2002). <br /> The stream-side tailings lying along the ditch on the south side of the Swan River valley <br /> near the IXURoyal Tiger site contain concentrations of copper and zinc that indicate a <br /> moderate risk to wildlife and livestock. Lead concentrations in these materials indicate a <br /> high risk to wildlife and livestock(CDPHE,2002). <br /> 8.2 Human Recreational Use <br /> There is currently no residential use of the site,and future land use is planned for <br /> recreational and natural-preservation uses. Based on the current and future land use, <br /> measured concentrations in source materials were compared to the RMC benchmarks <br /> IXURoyal Tger VCUP Application Page 21 of 33 <br />