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Whirlwind Mine Groundwater Characterization Report <br /> The uppermost sandstone of the Salt Wash, the Top Rim sandstone, is the mineralized ore- <br /> bearing zone that is the target for uranium mining in the area. This unit is considered an <br /> aquiclude. There is no evidence of substantial yield of ground water from the Top Rim, either <br /> from historic mines, or borehole testing, or exploration drilling. Most historical mining in the area <br /> accessed the Top Rim through tunnels collared at the unit's outcrop. Whereas the Whirlwind <br /> Decline was collared upslope of the Top Rim outcrop in the Brushy Basin. Observations at the <br /> Packrat Mine, which accesses the ore zone from the Top Rim outcrop, have shown that <br /> groundwater flows into the mine through several exploration drill holes that intercept the <br /> workings. At least one vent shaft, the 10-Straight vent shaft, also is a conduit for overlying <br /> aquifer leakage into the mine. Several of the historic mines had mine discharge at the portals in <br /> the past, but these mines do not discharge presently. Testing at borehole BM00-1 and <br /> observations during exploration drilling by Cotter and EFR did not indicate the Salt Wash was <br /> an aquifer. <br /> Information on hydrogeologic conditions underlying the Salt Wash is lacking. However, the <br /> underlying Summerville formation is approximately 100 ft thick, consists of mudstone and shale, <br /> and is considered of relatively low permeability. <br /> Water chemistry indicates two primary water types are present in the study area. One water <br /> type is represented by Burro Canyon sources and include the Dolores Point well, DP Spring, the <br /> Cherokee Deep well, and Cherokee Shallow well. These sources show a calcium-bicarbonate <br /> type water. The other water type is represented by Brushy Basin sources including Whirlwind <br /> Decline, BM00-1-2 and BM00-1-3 from Umetco borehole BM00-1, and Monitoring Well W-1. <br /> Sources perceived to be associated with the Salt Wash include the Packrat Mine, the Rajah 49 <br /> Mine (Thornton Portal), and PR Spring. The chemistry from the Packrat Mine pool and the <br /> Rajah 49 Mine exhibit a sodium-bicarbonate water type similar to the Brushy Basin chemistry. <br /> This similarity may be due to inherent similarities in overall geochemistry of the two units, and/or <br /> be related to leakage through drill hole and vent shaft intercepts into these mines from overlying <br /> Brushy Basin aquifers. <br /> Other water sources sampled for the project show a water chemistry signature that may be a <br /> mix of Burro Canyon and Brushy Basin groundwaters or may indicate a local geologic source of <br /> different chemistry. These sources include PR Spring, Monitoring Well W 1, borehole test <br /> Western Water S Land, Inc. 61 <br />