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Reclamation Plan <br />This plan covers only the proposed permit area. No changes to other areas of the existing Home Office <br />Mine Site are made as a result of this plan. As described previously, mining is essentially complete <br />at the Treiber Lakes site. <br />Final Proposed Land Use <br />The principal goal of reclamation is to separate the existing groundwater lakes from the rest of <br />the alluvial groundwater system to create water storage reservoirs. The proposed final land use <br />is water storage. This land use is consistent with existing and future land uses in the area. <br />General Overview of the Reclamation Plan <br />Reclamation of the proposed Treiber Lakes site is fairly straightforward. Lining the Treiber <br />Lakes will require establishing a relatively impermeable seal on the bottom and sides of the <br />excavated areas. The liner will effectively separate the water inside the reservoir from adjacent <br />alluvial groundwater and potential bedrock groundwater below. Slurry wall technology has been <br />used successfully in many situations to provide the vertical, relatively impermeable barrier <br />between alluvial groundwater and below -grade reservoirs. At the Treiber Lakes site, as in many <br />areas of Colorado, the shale and claystone bedrock encountered below alluvial deposits provides <br />an excellent low permeability barrier for the bottom seal of below -grade reservoirs. Based on <br />this understanding, conditions at the Treiber Lakes site are ideal for slurry wall construction and <br />below -grade water storage. <br />Reservoir Performance Standards <br />Treiber Lakes <br />DRMS 112 Permit Application <br />EXHIBIT E <br />According to the State Engineer's Office (SEO), the intent of the reservoir lining design (design <br />standard) is to achieve S groundwater inflow (leakage rate) into the reservoir that is not greater <br />than 0.03 ft/day (1 x 10 cm/sec) multiplied by the length of the perimeter wall in feet multiplied <br />by the average vertical depth of the perimeter wall as measured from the ground surface to the <br />pit bottom along the toe of the pit side slope, plus 0.0015 ft/day (5 x 1e cm/sec) multiplied by <br />the area of the bottom of the liner system or natural bedrock bounded by the perimeter wall. <br />The performance standard shall be three times the design standard and shall be applied to an <br />initial test of competency of the liner, as well as to the ongoing operation of the reservoir. The <br />initial test will include a water balance analysis to demonstrate that the balance of the inflows <br />and outflows equals the change in storage volume over a minimum of a 90 -day period. <br />Slurry Wall Construction <br />As mentioned previously, slurry wall technology has been used successfully in many situations <br />to provide a vertical, relatively impermeable barrier between alluvial groundwater and <br />below -grade reservoirs. Slurry walls (also known as slurry cut -off walls or slurry trenches) are <br />Page 8 <br />