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• Potential Ground Yeter Use. Potential ground water suitability et the Yoest mining area <br />was evaluated by compering sample enelyte concentrations from monitoring wells completed <br />in the various geologic units with three categories of water quality standards. The three <br />categories of water quality stenderds, based on water useg e, are: 1) domestic drinking; <br />2) irrigation; end 3) livestock. <br />Domestic, irrigation, end livestock standards were compared to the baseline ground water <br />quality measured in the various geologic units to determine if they exhibit any water use <br />potential that would need to be protected end to define the type o} ground water quality <br />that is mixing with any downgradient units in hydraulic communication. The domestic <br />standards consist of EPA and CDON criteri e. Irrigation stenderds consist of CDOH criteria <br />end parameter limits recommended by the California State Water Resources Control Board <br />(7963), the Food and Agriculture Organization of the United Nations (Kendiah, A., 1987), <br />end CMLRD (7988). Livestock standards consist of CDOH criteria end parameter limits <br />recommended by the Ontario Ministry of the Environment (1984), the National Academy of <br />Sciences (1974), and Wyoming's Department of Environmental duality (1980). In ell cases, <br />if a CDON standard and some other standard or criteria exist for the same parameter, the <br />• CDON standard was used for comparison purposes. <br />Domestic Drinking Water Suitability. Of the three categories of water quality standards <br />evaluated, the domestic criteria ere the most stringent. Table 7-19 presents a listing of <br />the domestic water quality standards. The standards listed in Table 7-19 were compered <br />against ground water sample enelyte concentrations on a well-by-well basis. Table 7-20 <br />presents the comparison results, including the domestic standard, the monitoring well(s) <br />where concentrations have exceeded each standard, and the frequencies of exceedences. <br />Table 7-20 shows that ground water monitored in eLl geologic units et the Yoest mining <br />area commonly exceed domestic drinking water standards for manganese, toteL dissolved <br />solids, and sulfate. Occasional exceedences were also noted for iron (all units except <br />Annend Draw alluvium). At least one exceedence of the cadmium standard was observed in <br />the Annend Draw and Sage Creek alluvium, Yedge overburden, end the Yedge underburden. <br />Lead end selenium standards were exceeded et least once in the Lennox overburden. Barium <br />was commonly exceeded at Yedge coal Yell YY30; however, analytical results for barium at <br />all other Yoest monitoring wells were less than the 1000 ug/l domestic drinking water <br />. standard. Exceedences of the arsenic end cadmium standards at Yedge coal Yell YY7 ere not <br />considered representative of the Yedge coal seem (see previous section "Wedge Coal's under <br />Ground Voter duality). <br />57 Revised 03/01/95 <br />