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JD-9 Mine Report <br />Geoscience Services <br />mudstones of the Brushy Basin Member of the Morison that underlie the JD-9 mine site <br />but aze absent at the SM-18 mine site. The Brushy Basin Member provides additional <br />distance and retardation for potential constituents of concem migrating from the waste <br />rock pile at the JD-9 mine. The figures show the extent of contamination after 1000 <br />yeazs of transport under steady-state conditions. The concentration intervals represent <br />1/1000' and 1/1E-06 of the initial concentration of constituents of concern in the pore <br />water of the waste rock pile. <br />Uranium and selenium were chosen to show the impact of unsaturated flow and <br />sorption on the transport of contamination. Uranium exhibits the lowest Kd value for <br />sandstone of the analytes selected in the SPLP tests. Consequently, uranium will behave <br />more conservatively, or in other words, will be sorbed to the geologic material to a lesser <br />degree resulting in larger transport distances. As shown in Figure 2, uranium is predicted <br />to migrate approximately 200 feet vertically at a concentration of 10~ of the original <br />concentration in the pore water of the waste rock. There is approximately 200 feet of <br />Brushy Basin overlying the Salt Wash at the JD-9 mine site. Consequently, constituents <br />of concern from the waste rock would be contained in the Brushy Member of the <br />Morrison Formation. It appeazs unlikely that contamination would reach the Salt Wash <br />Member for possible horizontal transport toward Bull Canyon. The modeling further <br />shows that the plume does not enter the Entrada Sandstone, the regional aquifer for the <br />area. <br />Using the SPLP tests for ore from the SM-18 mine of 2700 ug/L, uranium was not <br />found in the waste rock at the JD-9 mine, the predicted concentration at 200 feet below <br />the waste rock pile would be 0.0027 ug/L. To meet water quality standards required by <br />the Colorado Division of Mineral and Geology (which is a compazison to surface water <br />standards of the Lower Dolores River Basin, CDPHE Regulation No. 35), a dilution <br />factor of 9x for uranium is necessary. The modeling simulation showed a dilution factor <br />of a million times for pore water in the unsatwated zone-a factor of 105 higher than <br />required by the Colorado DMG. <br />ll <br />