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0 Uranium <br />Expected range of concentrations: 0.1 to 1.7 mg/L <br />Discharge standard: Average and maximum discharge limits of 0.7 and 1.1 mg/L, <br />respectively. <br />Uranium, like radium, may be removed from water by the addition of barium chloride <br />(BaCI). Lyntek's bench scale testing at the La Sal, Utah mine showed that uranium <br />concentrations in mine water with a pH of 8.8 were reduced from 0.1 mg/L (68 pCi/L) to <br />0.049 mg/L (33 pCi/L) with the addition of barium chloride and ferric sulfate at the <br />design dosage. Additional secondary treatment with filters and resin columns are <br />typically necessary to achieve the drinking water standard of 0.030 mg/L. <br />Arsenic <br />Expected range of concentrations: 0.02 to 1.2 mg/L <br />Discharge standard: Average of 0.1 mg/L <br />Dissolved arsenic can be precipitated from water by raising the pH to 10.00 or higher, by <br />the addition of lime or caustic. This is considered unrealistic for this project due to the <br />resulting high volume of sludge produced. Elevated levels of arsenic can be also be <br />removed from water to achieve levels of less than 10 parts per billion (<0.01 mg/L) by <br />elevating the pH to a range of 8.7 to 8.8, if sufficient levels of iron are present. <br />The current available data shows that the average pH of the mine drainage is 8.5 to 8.8; <br />this pH range should be sufficiently high to precipitate the metals species of concern <br />without addition of lime to raise the pH. <br />A co-precipitation occurs with the arsenic and the available iron. Dissolved iron is <br />relatively low in the mine water (<O.1 mg/L) but can be increased by adding ferric sulfate <br />(FeS04) during treatment with an approximate ratio of 3:1, Iron (as Fe+3) to arsenic. Iron <br />should only be added in sufficient quantity to precipitate the arsenic to meet the site- <br />specific discharge standard, while remaining in compliance with the Colorado discharge <br />limit for dissolved iron (i.e., 0.3 mg/L). <br />Selenium <br />Expected range of concentrations: 0.02 to 0.35 mg/L <br />Discharge standard: Average of 0.02 mg/L <br />It has been shown that Selenium can co-precipitate with iron. The water treatment system <br />proposed would provide excess iron that is expected to co-precipitate some of the <br />Selenium. This should be adequate for the Whirlwind Tunnel water, which has selenium <br />concentrations near the discharge limit. However, if higher concentrations (i.e., up to 0.35 <br />r1, <br />LJ <br />6