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JD-6 Mine Report <br />Geoscience Services <br />The figures show the extent of contamination after 1000 years of transport under <br />steady-state conditions. The concentration intervals represent 1/1000t1i and 1/1E-06 of <br />the initial concentration of constituents of concern in the pore water of the waste rock pile <br />I: Uranium and selenium were chosen to show the impact of unsaturated flow and <br /> sorption on the transport of potential contamination. Uranium exhibits the lowest Kd <br />• value for sandstone of the analyzes selected in the SPLP tests. Consequently, uranium <br /> will behave more conservatively, or in other words, will be sorbed to the geologic <br />~ material to a lesser degree resulting in larger transport distances. As shown in Figure 3, <br />~ uranium is predicted to migrate approximately 200 feet vertically at a concentration of <br /> 10~ of the original concentration in the pore water of the waste rock. The uranium plume <br /> <br /> is contained in the Salt Wash Member of the Morrison Formation. The plume does not <br />• enter the Entrada Sandstone, the regional aquifer for the area. The Summerville <br /> Formation provides an additional buffer zone restricting potential contamination from <br />~ entering the groundwater. <br /> <br /> Using the SPLP tests for ore from the SM-18 mine of 2700 ug/L, uranium was not <br /> <br />• found in the waste rock at the 7D-6 mine, the predicted concentrafion 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 Geotogy (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 fimes for pore water in the unsaturated zone-a factor of 105 higher than <br /> <br /> required by the Colorado DMG. <br /> <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 1E-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-6, the resultant concentration at a <br /> <br /> depth of 80 feet below the pile would be 0.000061 ug/L. Once again, this represents a <br /> <br /> 11 <br /> <br /> <br />