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Response to DRMS Adequacy Review — Cotter JD -8 Mine Reclamation Plan Amendment <br />include a clay liner, limited contact time, and surface water controls (ditches and <br />berms). <br />A compacted clay liner will be constructed below the ore storage pad with a <br />minimum 12 -inch thickness. The clay is available from a nearby property, and will <br />be transported, applied in lifts, and compacted to minimize the hydraulic <br />conductivity. Prior to the selection of the clay source, samples will be collected and <br />analyzed in the laboratory for cation exchange capacity ( "CEC "). Modified <br />Standard Proctor Tests will be also performed, and a plot of moisture content vs. <br />dry unit weight will be prepared to determine the Line of Optimums. The optimum <br />placed moisture content for the clay will be determined, and used to guide the <br />construction with a goal of achieving a place hydraulic conductivity of less than 5 x <br />10-6 cm/sec. (Typically the lowest values of hydraulic conductivity occur when the <br />dry unit weight is high and the moisture content is on the wet side of optimum.) <br />Low hydraulic conductivity is expected to be just one factor in reducing the <br />potential for transport of radioactive material from the ore pad. The underground <br />ore typically occurs above the water table, and the ore will therefore be dry when <br />placed on the pad. Atmospheric conditions at the site will further limit infiltration <br />because potential evaporation exceeds precipitation. Further, the cation exchange <br />capacity of the clays will contribute to sorption of uranium or other metals, should <br />seepage from the ore pad occur. <br />Ore will be rotated so that no fraction of the ore remains on the ore pad for longer <br />than 180 days. Although the overall ore pad may contain ore continually, older ore <br />will be transported from the pad to make way for freshly mined ore, so that no <br />fraction of the ore remains on the ore pad for longer than 180 days. The limited <br />duration of exposure to atmospheric conditions will limit the potential for <br />weathering, release, and transport of constituents from the ore. <br />Surface water contact with the ore pad will be reduced or eliminated by ditches and <br />berms constructed around the perimeter of the ore pad, as appropriate. These <br />ditches and/or berms will prevent upslope surface water runon from contacting the <br />ore. The ditches and berms will be constructed to allow access by haul trucks and <br />will be inspected and maintained regularly. <br />(18) All EPP maps appear to show growth media stockpiles and waste rock piles overlapping. <br />Please correct. <br />Cotter response: The growth media stockpile is temporary and will be consumed or <br />relocated as reclamation progresses. In the final configuration, all growth media <br />will be utilized in reclamation for revegetation, and the waste rock pile will occupy <br />the area formerly occupied by the growth media stockpile. Therefore, the drawings <br />showing the final waste rock pile overlapping the current growth media stockpile <br />are correct. <br />Page 14 <br />