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Environmental Protection Plan, Schwartzwalder Mine 11-9 <br />Table 11-6. Comparison of Water Quality in Ralston Creek to Applicable Aquatic <br />Standards <br />• <br />Parameter Units Summary Statistics Aquatic Standards (based on average Number of Exceedences <br /> hardness at SW-BPL) <br /> # of Samples # of ND % ND Acute Chronic # of Acute # of Chronic <br />pH S.U. 142 0 0% 6.5-9.0 6.5-9.0 0 0 <br />Nitrate Nitrogen mg/L 122 56 46% 10 10 0 0 <br />Ammonia, total mg/L 135 98 73% 22.8 5.77 18* 20* <br />Sulfate mg/L 255 0 0% 250 250 8 8 <br />Chloride mg/L 251 0 0% 250 250 0 0 <br />Aluminum, total mg/L 125 104 83% 0.75 0.087 2 18 <br />Arsenic, total mg/L 162 162 100% 0.05 --- 0 --- <br />Boron, total mg/L 36 20 56% 0.75 0.75 0 0 <br />Cadmium, dissolved mg/L 73 73 100% 0.0026 0.00061 0 0 <br />Chromium, dissolved mg/L 70 69 99% 0.016 0.011 0 0 <br />Cyanide, total mg/L 11 11 100% 0.005 0.005 0 0 <br />Copper, dissolved mg/L 250 218 87% 0.0213 0.0136 1 2 <br />Iron, dissolved mg/L 197 130 66% --- 0.3 --- 3 <br />Iron, total mg/L 114 25 22% --- 1 --- 1 <br />Lead, dissolved mg/L 62 62 100% 0.1095 0.00427 0 1 <br />Lead, total mg/L 162 155 96% 0.1095 0.00427 --- --- <br />Manganese, dissolved mg/L 227 195 86% 3.513 1.941 0 0 <br />Manganese, total mg/L 121 81 67% 3.513 1.941 --- --- <br />Mercury, total mg/L 124 120 97% --- 0 --- 1 <br />Nickel, dissolved m 95 95 100% 0.7079 0.0786 0 0 <br />Selenium, dissolved mg/L 95 95 100% 1.84E-05 0.0000046 0 0 <br />Silver, dissolved mg/L 80 80 100% 0.0047 0.00074 0 0 <br />Thallium, dissolved mg/L 263 258 98% --- 0.015 --- 0 <br />Zinc, dissolved mg/L 85 82 96% 0.2174 0.1885 0 0 <br />Uranium, dissolved mg/L 640 0 0% 4.116 2.571 0 0 <br />Uranium, suspended mg/L 417 238 57% 4.116 2.571 0 0 <br />Uranium, total mg/L 21 0 0% 4.116 2.571 0 0 <br />Radium-226, dissolved pCi/L 504 113 22% 5 5 0 0 <br />Radium-226, suspended Ci/L 396 312 79% 5 5 0 0 <br />* Aluminum standard based on total recoverable concentrations <br />(i) Water Quality During Operation of the Sumps and WTP <br />While the sumps and water treatment plant were operating, the TDS in Ralston Creek increased to about <br />250 mg/L and the water changed to a calcium-magnesium-sodium-bicarbonate water as Ralston Creek <br />flowed past the mine site (Figure 11-1). TDS concentrations varied seasonally (Figure 11-2), and were <br />generally highest during the winter months and lowest during the spring months. Bicarbonate and sulfate <br />were the dominant components of TDS in Ralston Creek adjacent to and below the mine site (Figure 11-2). <br />Sulfate concentrations averaged 20 mg/L upstream of the mine and 68 mg/L downstream of the mine, and <br />did not exceed the water quality standard of 250 mg/L in any of the samples analyzed. <br />The shift from a calcium-bicarbonate type water to a calcium-magnesium-sodium-bicarbonate type water <br />was evident in the Piper diagram of average water quality at 14 stations (13 stations in Ralston Creek plus <br />the treatment plant discharge.) Stations SW-UP, SW-UC, SW-AWD, and SW-A001 plot in a single cluster <br />in the cation field of the Piper diagram (Figure 11-3), while stations SW-BDIS, SW-OS, SW-BOS, SW- <br />GS, and SW-LLHG plot in separate cluster. The discharge water (Station SW-DIS001) had lower calcium <br />and higher sodium than the upstream and downstream waters (Table 11-7). <br />Minor ions and trace metal concentrations remained essentially constant upstream and downstream of the <br />mine, with the exception of uranium and molybdenum. Most trace metals were below detection at all <br />sample stations. Uranium increased from about 0.003 mg/L upstream of the mine to about 0.006 mg/L near <br />the downstream property boundary (Table 11-8), well below the drinking water intake standard of 0.059 <br />mg/L (40 pCi/L) and the hardness-based aquatic toxicity standards. Molybdenum increased from below <br />4109C.090807 Whetstone Associates