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• When Pond 1.2 reaches capacity for HDS storage, it will be decommissioned <br /> and closed in-situ. Henderson has presented its case in Section 2.0 that the <br /> HDS produced at the consolidated water treatment facility at the Urad Mine site <br /> is alkaline, non-hazardous, and does not meet the MLRB definition of <br /> "designated chemical" [Rule 1.1 (13)]. Therefore, Henderson intends to grade <br /> the stored HDS for positive drainage and cover Pond 1.2 with a semi-permeable <br /> multi-layered cap prior to final revegetation. <br /> 2.4.1 Grading <br /> Once Pond 1.2 has reached capacity, the HDS will be allowed to settle naturally <br /> for approximately 60 days prior to additional work. At the conclusion of the 60 <br /> days, the HDS will be configured to allow surface drainage to flow east and west <br /> from a divide across the center of the impoundment as shown in Figure 4. Berm <br /> edges will be graded onto the HDS within the pond so that snowmelt and <br /> precipitation will drain naturally to the interceptor ditches and not accumulate <br /> • either around the perimeter or anywhere else on the impoundment. <br /> 2.4.2 Cover <br /> Henderson is proposing to close the impoundment with a multi-layered, <br /> vegetated cap similar to those commonly used at non-hazardous metallic mine <br /> waste sites. This cap will consist of a 6 inch benign aggregate capillary <br /> barrier/drainage layer and 12 inches of growth media as illustrated conceptually <br /> in Figure 5. The capillary barrier will be tied into the interceptor ditches as <br /> shown on the ditch cross-sections on Figure 4. Growth media will be obtained <br /> off-site and spread either by rubber tire loaders or graders, or a small tracked <br /> cat. <br /> 2.4.3 Vegetation <br /> 14 Jane 29.7999 <br /> TRA= <br />