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JD-8 Mine Report <br />Geoscience Services <br />emanating from the JD-8 mine must travel through similar geology under similar <br />precipitation and subsequent recharge conditions. <br />The figures show the extent of contamination after 1000 years of transport under <br />steady-state conditions. The concentration intervals represent 1/1000`' and 1/1E-06 of <br />the initial concentration of constituents of concern in the pore water of the waste rock <br />pile. 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 lazger transport distances. As shown in Figure 3, 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. The uranium plume is contained in the <br />Salt Wash Member of the Morrison Formation. The plume does not enter the Entrada <br />Sandstone, the regional aquifer for the area. The Summerville Formation provides an <br />additional buffer zone restricting potential contamination from entering the groundwater. <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-8 mine, the predicted concentration at 200 feet below <br />the waste rock pile would be 0.0027 ug/L. To meet water quality values required by the <br />Colorado Division of Mineral and Geology (which is a comparison 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 unsaturated zone-a factor of 105 higher than <br />required by the Colorado DMG. <br />Selenium migration is illustrated in Figure 4 and the predicted transport distance <br />for a period of 1000 years is approximately 80 ft at a concentration of IE-06 of the <br />original pore-water concentration in the waste rock. Using the SPLP test results that <br />indicated 61 ug/L of selenium for the waste rock at JD-8, the resultant concentration at a <br />depth of 80 feet below the pile would be 0.000061 ug/L. Once again, this represents a <br />11 <br />