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• source of the uranium and other radionuclides that leached downward into the lower Brushy Basin and <br />Salt Wash sandstones. This leaching of the mudstones would also have resulted in calcium gradually <br />being replaced by sodium and potassium, which are abundant in these rocks. <br />Each of the water-bearing zones within the Brushy Basin are examined in more detail below. <br />Upper Brushy Basin Sandstone <br />The Upper sandstone is located near the Burro Canyon/Brushy Basin contact in a transition zone from <br />the Burro Canyon sandstones to the massive mudstones of the Brushy Basin. In many places on the <br />mesa, the lower Burro Canyon Aquifer and the Upper Brushy Basin Sandstone comprise a single <br />sandstone aquifer with only minor shale parting between the geologic units. However, the parting <br />between the sandstone units was greater at Boring BM00-1 and they are treated herein as separate <br />water-bearing zones. <br />An open-hole pumping test in BM00-1 from 93 to 140 feet bgs confirmed that the Upper Sandstone <br />• was capable of producing water. A water sample from this boring was not analyzed; however, data is <br />available for this water-bearing sandstone from two wells that are located near the Cherokee shaft, <br />approximately 2,000 feet east to southeast of the Whirlwind portal (see Maps G-1 and G-2). These <br />wells, which are located at a surface elevation of about 7,240 feet, supplied domestic water to the mine <br />camps that were located near the Cherokee shaft. The shallower well is uncased and approximately 40 <br />feet deep. The deep well is cased and 110 feet deep. <br />Both wells were sampled by the BLM. The shallow well, which had a static water level of 37 feet bgs, <br />was sampled in 1999. The deeper well had a static water level of 77 feet bgs and was sampled in 2000. <br />The sample analyses showed that the ground water was similar in both wells with acalcium- <br />bicarbonate signature and low levels of radionuclides. This water had slightly more sodium and less <br />calcium than the Burro Canyon water, but otherwise was very similar in quality. The analytical results <br />for both wells are presented in Table E-l .The major ion chemistry of the deeper well sample is plotted <br />on Figure G6 for comparison purposes. Willow Spring, which is located southeast of Beaver Mesa in <br />John Brown Canyon, has similar ion chemistry to the Cherokee Wells and appears to originate from <br />• <br />Whirlwind Mine 07 (rev. April 08) G-11 <br />