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JD -7 Mine — Drainage Design Plan 2 <br />Sub -basin B2 occupies 489.9 acres and is roughly parallel to sub -basin 131. It extends from the crest of <br />Mongram Mesa to East Paradox Creek, also passing through the JD -7 topsoil stockpile area. Sub -basin 132 <br />is dominated by an incised intermittent channel and was the focus of a drainage reconnaissance survey for <br />the nearby JD -8 Mine (Whetstone, 2012). The steep upland areas in the southern portion of sub -basin 132 <br />(Figure 1) transition abruptly to the shallow slope of the valley floor (Figure 2) at the toe of the escarpment. <br />The field reconnaissance survey indicated that the unnamed perrenial channel cannot be traced to its <br />confluence with East Paradox Creek on the valley floor, because it is intersected by the existing 79.5 -acre <br />JD -7 topsoil stockpile (Plate 1, Figure 3). Stormwater that reaches the valley floor infiltrates or is dispersed <br />into non - channelized flow south of the soil stockpile. Soils in the valley floor (Figure 2) have high <br />permeability and low organic content, which favors infiltration to groundwater at the margins of the <br />Paradox Valley. <br />Figure 1. Photo Showing Dry Drainage and Sandy Streambed in Major Sub -Basin B2 <br />Sub -basin B3 occupies 1,293.8 acres and contains most of the JD -7 Mine features, including the existing <br />open pit, open pit waste rock pile (OPWRP), underground mine waste rock pile, and mine facilites (mine <br />portal, vent hole, waste rock stockpile, shop /dry building, fresh water tank, compressor shed, water <br />treatment shed, stormwater ponds, and two water treatment ponds). Sub -basin B3 originates at the crest of <br />Mongram Mesa and contains mostly ephemeral drainages and one mapped intermittent drainage in its <br />upper reaches. The steep slopes of the Monogram Mesa escarpment give way to the flat valley floor in the <br />western portion of sub -basin 133 and to hummocky foothills in the eastern portion of the sub -basin where <br />the JD -7 open pit and mine facilities are located. Downslope of the mine, braided ephemeral and <br />intermittent channels route stormwater north across the low - gradient floor of the Paradox Valley (2% <br />slope) to East Paradox Creek. <br />4149A.140207 Whetstone Associates <br />