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Several of the geologic units in the area exhibit low permeability values and restrict the <br />downward movement of water from surface recharge to underlying aquifers. UMETCO <br />(1997) conducted a series of packer test in the Summerville Formation to measure the <br />hydraulic conductivity for work involving the Uravan Mill and the associated waste <br />disposal facility located on Club Mesa. These tests, conducted at 167 to 270 psi, did not <br />introduce any water into the formation, indicating that the hydraulic conductivity of the <br />Summerville Formation is no greater than 1.0 E -08 cm/s. This conclusion is supported <br />by laboratory testing that measured horizontal and vertical permeabilities of less than 9.7 <br />E -10 cm/s. For all practical purposes, this low permeability value indicates that the <br />Summerville Formation is an aquiclude — rock incapable of transmitting groundwater. <br />Peel Environmental Services (1993) conducted hydraulic tests of the Kayenta Formation <br />using packer tests that showed the formation did not take water at a pressure of 745 psi. <br />Based on these tests, the report estimated that the permeability of the portions of Kayenta <br />Formation is 3.8E -08 cm/s — basically impermeable. The test interval was in a shale unit <br />of the Kayenta Formation and is not representative of the entire formation. However, the <br />lowest permeability unit controls flow for the entire formation. <br />For mining to impact the regional groundwater system, mobilized constituents would <br />have to migrate from the upper sandstone unit of the Salt Wash member through the <br />lower sandstones and bentonitic shales of the lower portion of the Salt Wash and through <br />the impermeable Summerville Formation to reach the Entrada Formation that may not <br />even contain groundwater in the JD -9 mine area. It is clear that uranium mining will not <br />impact valuable groundwater resources. <br />8.3.4 Recharge <br />As noted in Section 8.3.1, the Dakota/Burro Canyon Formation forms the highlands <br />above the mine site and the exposed bedrock across the surface provides significantly <br />more area for recharge compared to the canyon walls for the lower stratigraphic units. <br />While groundwater may occur in the springs at the Burro Canyon/Brushy Basin contact, <br />there are no mapped springs in highland area. There are indications of seeps in the area <br />where vegetation shows increases in moisture contents of the surrounding soils at the <br />Burro Canyon/Brushy Basin contact. <br />The presence of water in the Salt Wash sandstones is not consistent with other mining <br />sites in the Uravan Mineral Belt. The most likely explanation is the surface area <br />available for precipitation to recharge the low permeable sandstones. In other regions of <br />the Colorado Plateau, exposures of the Salt Wash sandstones are limited to outcrops <br />along valley walls. Similar to the Burro Canyon Formation that forms highland and mesa <br />in the area, the Salt Wash Member of the Morrison Formation forms benches in the <br />region surrounding the JD -9 Mine. To the north, in the Gregory Creek and Wild Steer <br />Canyon area, the Salt Wash forms an extensive bench area exposing large areas of the <br />rock to available precipitation. To the south, the Fawn Spring Bench, as designated by <br />Cater (1954), is formed by the resistant sandstones of the Salt Wash. The increase in <br />O'Connor Design Group Inc. U - 16 <br />