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• Lower Brushy Basin Sandstone <br />Several thick sequences of sandstone were encountered in Boring BM00-1 near the base of the Brushy <br />Basin at depths of 360 to 371 feet bgs and 388 to 437 feet bgs. This is 70 to 150 feet above the Brushy <br />Basin/Salt Wash contact at 510 feet bgs. Packer tests were conducted over intervals of 355 to 400 feet <br />and 395 to 440 feet. Sixty gallons of water were pumped from each interval before Samples BM00-1-2 <br />and 3 were collected. Both samples were sodium-bicarbonate waters with increasing levels of sulfate <br />and total dissolved solids when compared to samples collected higher up in the Brushy Basin. As <br />shown in Table E-1, radionuclides were present in both samples and elevated above regulatory <br />standards for combined radium-226 and 228 in the upper sample (i.e., 41 picoCuries per liter (pCi/L) <br />compared to a standard of 5 pCi/L). The elevated radionuclide levels in the upper packer test are also <br />evident on the hole's gamma log, which is shown on the left-hand side of Figure G5. The meq ratios <br />for major ions from the two samples are plotted on Figure G6. <br />Cotter's 1996 exploration program could not identify ground water inflow rates in the Lower Brushy <br />Basin Sandstone because the holes were not cased during drilling and occurrences of ground water <br />• below the initial intercept (i.e., Middle Brushy Basin Sandstone) could not be determined. However, <br />the Whirlwind Decline intercepts the Lower Brushy Basin Sandstone starting at an approximate <br />elevation of 6,848 feet. Accounting for formation dip, this corresponds well with the initial drilling <br />intercept reported above for the Lower Brushy Basin Sandstone. Historic information collected by <br />Pioneer Nuclear Inc. indicated that an average of 5.3 gpm of ground water flowed into the nominal 9- <br />foot high by 12-foot wide decline over a five month period from late November 1981 through early <br />May 1982 after mining operations shutdown. More recent monitoring by Energy Fuels shows that <br />current inflows are at about 1 to 2 gpm over about 100 feet of tunnel length. The sandstone lens <br />continues above the seep area for several hundred more feet; however, this upper portion of the <br />sandstone lens does not appear to contain any ground water. <br />6.3 Salt Wash Aquifers <br />A thick sequence of sandstone was encountered in Boring BM00-1 at the top of the Salt Wash from <br />510 feet bgs to 555 feet bgs. A packer test was conducted over the interval from 500 to 560 feet in an <br />effort to collect a background sample of ground water from the Salt Wash in advance of mining <br />• operations. The test interval was pumped for 40 minutes at which time the pump ran dry. The interval <br />Whirlwind Mine 07 (rev. April 08) G-13 <br />