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The evaluation procedure, which was developed mutually by the Operator and the Division, is <br />similar to procedures that the Division has accepted for other sites, including the Occidental Oil <br />Shale evaporation pond. <br />The Synthetic Precipitation Leach Procedure (SPLP) (EPA Method 1312) was used to <br />test representative samples of ore and waste rock from two mines. The samples were <br />tested for all regulated parameters considered to be potentially available in the rocks to <br />be mined at these deposits, specifically regulated parameters in the WQCC Regulation <br />41, Basic Standards for Groundwater. Based on proximity and similar geology and <br />mineralogy, a single sample from the JD-9 mine was considered by the Division to be <br />representative of the JD-8 and JD-6 mines. A sample from the SM-18 mine was <br />considered representative of the rocks at the mine alone. <br />The SPLP test is a rigorous, physically aggressive test that combines "synthetic" <br />rainwater with the solids, which are finely crushed, then tumbled together for a number of <br />hours. Afterwards, the leachate is tested according to standard wet chemical methods, <br />and the results reported. The Division considers this test to be "conservative" for several <br />reasons: (a) the rock samples present an extraordinarily high surface area to the <br />leachant, relative to what would be presented in the field; (b) the tumbling process <br />provides maximum exposure of all potentially reactive sites to the leachant; and (c) the <br />tumbling process exposes even more surface area through semi-autogenous grinding. <br />2. The SPLP test results were compared to the most restrictive (lowest value) water quality <br />standards established by the WQCC for groundwater in Regulation 41 (see Posey July <br />22, 2005 memo to Means). Parameters that exceeded the standard were evaluated by <br />determining the amount of dilution needed to meet the standard. Based on this simple <br />technique, it was held that both the ore and waste rock at both sets of mines exceeded <br />water quality standards for several parameters, based on this a simple numerical <br />comparison of SPLP results with groundwater quality standards. <br />3. Because compliance with numeric protection levels is measured in the groundwater at <br />established compliance point(s) downgradient, because there are no promulgated <br />standards for dissolved constituents in unsaturated soils or bedrock, and because to <br />push contaminants to the groundwater table requires the force of -and thereby dilution <br />by -rain or snowmelt waters, the operator was encouraged to evaluate the rate of <br />dilution that could be expected by this process. <br />4. Contaminant Transport Modeling was proposed and accepted by the Division. The first <br />modeling runs incorporated both the effects of dilution and sorption (to minerals in the <br />stratigraphic column). <br />5. The Division rejected the effects of sorption as being non-conservative. Modeling of <br />sorption presumes that contact between the contaminants is ideal, and the amount of <br />sorbing materials through which the contaminants must travel downward were not well <br />constrained. <br />3 <br />