2000-04-21_PERMIT FILE - M2000002 (5)

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Arsenal property, plume sizes and contaminant concentrations are steadily declining and can be expected to abate to acceptable levels some time in the coming years. B. Status of groundwater testing The operator has not submitted test results for any of the cited contaminants. The regulations do not evidently require notice of contaminants, if such are present. However, the regulations do require a statement, under Exhibit G at (l), (2)(a), (2)(b), and (2)(c) of the Permit Application, saying whether groundwater systems will be afY'ected and how such effects will be managed. C. Need for an NPDES discharge pennit. As indicated by the operator and its representatives, the company is aware that water discharged to waters of the state will need to be regulated through an NPDES or CDPS permit. The operator has indicated that application for such permit is being prepared. D. Potential for withdrawal of off-site contaminants through aumoing. It appears from first principles that groundwater extraction for mining in the proposed area could locally affect the flow of groundwater, which has been .identified as containing DIMP, potentially causing that water to report to the gravel operation's pumping system. Provided there are contaminants still in the plume, the operator would need to handle such water in a manner compatible with required measures to protect human health and the environment, and to effect compliance with discharge regulations [o surface water. Withdrawal of contaminated water from the plume is not, per se, an issue regulated by the Division of Minerals and Geology. RECOMMENDATIONS It is recommended that the Operator consult EPA or US Arnty documents and determine current contaminant levels of D[MP and TCLEE in and around section ] 0. which contains the operation. All well monitoring information for DIMP and TCLEE in Section ]0 and up [o '/< mile outside section 10 should be evaluated. 2. Provided DIMP or TCLEE in concentrations exceeding drinking water standards occurs in any of the wells cited in Recommendation 1, the operator determine whether such contaminants will be collected via the mine pump system, and how such contaminants will be handled prior to discharge. 3. Provided DIMP or TCLEE in concentrations exceeding drinking water standards occurs in any of the wells cited in Recommendation 1, it is recommended that the operator report the health risks associated with withdrawal of such contaminants. At a minimum, the operator should furnish to the Division an MSDS report on each of the contaminants found in the groundwater contaminant evaluation cited in Recommendation 1, above. cc: Carl Mount Bruce Hwnphries