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July 30, 2010 8 of 24 <br />of uranium from solution that is presently occurring as a result of reducing (non-oxygenated) <br />conditions in the flooded mine should be allowed to continue to allow for the longest contact time, <br />and therefore lower mobility, of uranium. <br />If the mine pool were pumped down to the 500 level, all of the wall rocks in the exposed workings <br />would be exposed to oxygen. The surface area of the wall rocks in the 200, 300, 400, and 500 <br />levels is estimated to be 31,000 ft2 based on known mine void volumes. Those surfaces are <br />currently not exposed to oxygen, because water in the mine pool contains little or no dissolved <br />oxygen. Only the upper workings and the small surface areas of the mine pool are currently <br />exposed to oxygen. If the water level is lowered and the mine walls are exposed, then the oxygen <br />can directly attack the uranium minerals and dissolve both the precipitates that have accumulated <br />as the mine flooded and solid-phase uranium minerals remaining in the wall rock. <br />The data at the Schwartzwalder site is consistent with the literature. Uranium geochemistry, <br />including the processes that are occurring at the Schwartzwalder Mine, is well understood in the <br />scientific community. <br />VALIDITY AND REPRESENTATIVENESS OF PACKER TEST RESULTS AND <br />COMPARISON TO "SANDSTONE" <br />"The Division asserts that the packer tests performed by the operator are unlikely to be <br />representative of the entire hydrogeologic system. The Division presented evidence that fractured <br />igneous and metamorphic rocks can have a hydraulic conductivity 100, 000 times greater than the <br />packer test results (the 22 packer tests results gave a geometric mean hydraulic conductivity of 4.7 <br />X 10"7 cm/sec). The Division provided evidence that the rock mass hydraulic conductivity is <br />similar to sandstone (Division power point presentation, Range of Hydraulic Conductivity and <br />Permeability, from Freeze and Cherry, 1979.) "(See Draft Order, Paragraph 25) <br />Comparison of the metamorphic rock mass at the Schwartzwalder mine to a hypothetical <br />sandstone is an irrelevant and misleading characterization that seems to imply the rocks at the <br />mine are more permeable than the quantitative test data indicate. While some sandstones may <br />have permeabilities as low as 1 x 10. cm/sec (which is considered to be very low and would yield <br />water at a visually imperceptible rate to a 2,000-foot deep well) the Division appears to be <br />erroneously painting a picture of a high-yield sandstone aquifer which is inconsistent with both the <br />site geology and site-specific hydrologic data. <br />According to the referenced chart from the introductory groundwater hydrology text book (Freeze <br />and Cherry, 1979), the hydraulic conductivity for fractured igneous and metamorphic rocks may <br />range over about four orders of magnitude from 2 x 10-2 cm/sec to 8 x 10"7 cm/sec. The cited <br />hydraulic conductivity of unfractured igneous and metamorphic rock is much lower, ranging from <br />about 2 x 10 '10 cm/sec to about 2 x 10"12 cm/sec. Permeability in the fractured metamorphic rock <br />mass at the Schwartzwalder Mine is unequally distributed and is dominated by irregular and <br />widely spaced fractures. The intrinsic permeability of unfractured metamorphic rocks is very low <br />as suggested bi the range presented in Freeze and Cherry (i.e. between about 2 x 10 -10 cm/sec to <br />about 2 x 10"1 cm/sec). Brittle fracture zones may have much higher permeability that is also <br />encompassed by the range cited by Freeze and Cherry (2 x 10"2 cm/sec to 8 x 10.7 cm/sec). Packer