2012-10-01_REVISION - M1977311 (12)

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potentially accumulate. Any fractures in the bentonite shales would seal with moisture due to the expansive nature of the shales. Since meteoric water that accumulated in isolated lenses of sandstone and conglomerate had to move through impermeable bentonitic shale that dominates the lithology, the evidence suggests that this water is connate. The definition of connate water is water trapped in sediments at the time of their deposition (Freeze and Cherry, 1979). If this analysis is correct, the data suggest that the water in the Brushy Basin was deposited in the Jurassic Period of earth's history indicating that the age of the water is at least 145 million years old. This is a clear indication that the Brushy Basin is not a pathway for exposure or recharge for the underlying Salt Wash sandstones. The distribution of moisture data from the borings shows limited vertical and horizontal extent of water - bearing zones, indicating that, if saturated conditions occur in the subsurface, these zones are isolated. Sandstone beds below the ore horizon in the Salt Wash Member show few "moist" zones. In the northern portion of the site, just below the ore horizon, there are three borings that showed moist conditions at approximately the same depth. There are several dry borings that are near this area indicating a limited extent of moisture. While one of the borings showed a moist zone in the ore horizon, this is the only boring drilled to delineate the ore that encountered moisture and there was no indication of water in the mine during operations. Hydrologically, these isolated zones, if they were saturated, would be referred to as perched water bodies. There is no indication that a continuous groundwater pathway exists for the transport of uranium related constituents - either in the Brushy Basin or the upper sandstone units of the Salt Wash Member of the Morrison Formation. 8.5 Geochemistry of Uranium Deposits The next factor to consider for the potential mobilization of constituents associated with uranium deposits is the geochemistry of the uranium deposits. For Colorado Plateau deposits, the chief ore mineral is carnotite and it was initially believed by many to be a primary sedimentary mineral, precipitated during or shortly after the deposition of the enclosing sediments (Fischer, 1942). Carnotite is fully oxidized. The discovery of increasing amounts of uraninite in deeper deposits began to raise a valence problem. The possibility began to develop that uraninite is an early uranium mineral and that carnotite is an oxidation product - the result of weathering (Garrels and Christ (1965). Hostetler and Garrels (1962) used Eh -pH diagram to illustrate the conditions under which uranium might be transported by groundwater in the presence of vanadium. The diagrams shows that for conditions of groundwater with a pH greater than 2 and oxidizing conditions, carnotite is stable and the dominant mineral. Several other studies suggest that uranium minerals, especially minerals that contain vanadium, are relatively insoluble including carnotite. O'Connor Design Group Inc. T - 15