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JD-8 Mine Report <br />Geoscience Services <br />For the simulations, a conservative approach was adopted that assumed aworst-case <br />scenario. Because there is a limited amount of technical data available for the hydraulic <br />and transport parameters of the geologic strata under the site, these pazazneters were <br />estimated using the best available geotechnical data available from the literature. Since <br />there is commonly a range of values associated with these hydraulic and geochemical <br />pazameters, values that result in the highest transport rates were selected. <br />Z.0 Site Description <br />The JD-8 mine is located on the southwestern flank of Paradox Valley-a <br />breached anticline (Figure 1). The regional dip in the area is to the southwest away from <br />the center of the valley. Since the geologic structure will control the movement of <br />groundwater, the regional groundwater flow direction is also in a southwest direction-- <br />especially for the Entrada Sandstone aquifer. This area is also chazacterized by a series <br />of fault controlled rotational slumps where large blocks of bedrock have slid downward. <br />(Figure 2) The dip of these blocks is also in a southwestem direction but can exhibit a <br />greater dip angle due to the rotational movement of the bedrock. <br />According to Cater (1954), the waste dump for the JD-8 mine is located on the <br />Brushy Basin and Salt Wash Member of the Morrison Formation. Infiltrating water <br />would move through the waste dump material into the underlying Brushy Basin/Salt <br />Wash sandstones and mudstone, through the Summerville Formation, and eventually <br />enter the Entrada Sandstone. Since the geologic structure controls the movement of <br />groundwater, once water enters the Entrada it would flow to the southwest away from <br />Paradox Valley. It is unlikely that groundwater flow in the Entrada would extend for any <br />significant distance since the formation is terminated along the rotational fault plan. <br />There is the possibility of subsurface water movement along the bedrock and the nearby <br />landslide and alluvial deposits. Infiltrating water could move along this <br />consolidated/unconsolidated rock interface toward the center of the valley. Considering <br />the rate of groundwater flow, typical on the order of tens of feet per year, the bulk of this <br />2 <br />