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JD-9 Mine Report <br />Geoscience Services <br />Selenium migration is illustrated in Figure 3 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-9, 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 />dilution factor of 106--far exceeding the requirement of SOx required by the Colorado <br />Division of Mineral and Geology for groundwater. Even higher selenium values of 265 <br />ug/L reported for ore piles would result in 0.000265 ug/L--still far exceeding the SOx <br />dilution requirement Since selenium is contained in the upper portions of the Salt Wash <br />and does not reach the groundwater, there is substantial protection of the groundwater <br />resources in the area. <br />Comparing the extent of uranium and selenium migration shown in Figures 2 and <br />3, illustrates the effects of sorption. Selenium exhibits a Kd value for sandstone four <br />times higher than uranium resulting in greater sorption and the subsequent retardation of <br />the selenium plume. The other analytes such as aluminum, lead and assenic would <br />behave in a similar manner and pose no significant threat to the underlying groundwater <br />resources. This statement is based on the facts that uranium exhibits the highest degree <br />of mobility in the subsurface and a concentration an order a magnitude higher than any <br />values for waste rock or ore measured for aluminum, lead, or arsenic. Consequently, the <br />extent of migrations in the subsurface for these additional constituents of concern would <br />be significantly less than uranium. An exception to this is copper that was measured at <br />23,900 ug/L in the ore. Since copper would behave in a similar manner to selenium, the <br />concentration of at 80 ft below the ore pile after 1,000 years would be 0.0239 ug/I~well <br />below any water quality standazd. <br />6.0 Conclusions and Recommendations <br />Numerical modeling studies of the transport of constituents of concern from the <br />waste rock pile (or temporary ore storage piles) at the SM-18 mine and applied to the JD- <br />9 mine indicate that the pile poses no significant threat to underlying groundwater <br />12 <br />