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SUNDAY MINE COMPLEX-HYDROGEOLOGIC REPORT <br /> respectively, in 12 samples at downgradient well MW-SUN1; uranium and gross alpha are <br /> exceeded 5 and 10 times, respectively, in the intermediate well MW-SUN2, and gross alpha is <br /> exceeded 5 times in the upgradient well MW-SUN3. Uranium concentrations increase <br /> downgradient, that is, from northeast to southwest, with the highest concentrations in well MW- <br /> SUN1. <br /> Groundwater at upgradient well MW-SUN3 has the least saline composition of all samples <br /> collected. MW-SUN3 water does not exceed any BSGWs except once for iron and 5 times for <br /> gross alpha. The MW-SUN3 groundwater has the lowest uranium concentrations but the highest <br /> gross alpha, gross beta, radium-226, and radium-228 concentrations of the three monitoring <br /> wells. Underground mine samples, with the exception of the S-8 vent shaft, had the highest <br /> concentrations of uranium, vanadium, gross alpha, and gross beta. <br /> Hydrogeologic Conceptual Model <br /> A hydrogeologic conceptual model was developed using available information from past SMC <br /> reports and the new data acquired for this study. The hydrogeologic conceptual model applies <br /> to the occurrence and flow of groundwater in the Top Rim Sandstone unit of the Salt Wash <br /> Member, which is the ore bearing zone that is being mined. <br /> Groundwater in the Top Rim unit is present in the deeper workings of the SMC and is monitored <br /> in three monitoring wells installed at upgradient, intermediate, and downgradient locations <br /> relative to the SMC. Recharge to the Top Rim, or Salt Wash Member in general, is likely <br /> insignificant in the upgradient locations near the SMC portals, as only minor outcrops occur in <br /> this area. Recharge may be more prevalent in highlands several miles to the west, west of the <br /> Dolores River where the Salt Wash outcrop is significant and higher elevations may experience <br /> greater precipitation. The Dolores River may also be a recharge source where it is in contact <br /> with the Salt Wash Member. Because the Salt Wash is confined by finer-grained strata, vertical <br /> recharge from over and underlying aquifers is considered minor. <br /> Discharge of the Top Rim unit likely occurs at exposed outcrop along Dolores River canyon <br /> mostly by way of evapotranspiration and springs and seeps. The unit is not tapped by area wells <br /> and is not being pumped. Some discharge may occur by way of leakage to over and underlying <br /> confining beds, especially where the Salt Wash is confined. <br /> Head elevation data indicate the potentiometric surface of the Top Rim is relatively flat in the <br /> SMC area; water level elevations at the Dolores River are approximately the same as observed <br /> Western Water& Land, Inc. xli <br />