2009-08-10_GENERAL DOCUMENTS - M1977300 (2)

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Environmental Protection Plan, Schwartzwalder Mine 17_? (ii).4 Domestic Well Water Quality 9-30 The domestic well is completed in Ralston Creek alluvium, across the creek from the water treatment plant. Water quality data for the domestic well are available from 28 sampling events between 2004 and 2008 (Table 9-5). Water quality results are summarized by moderate electrical conductivity (320 to 370 gS/cm) indicating low to moderate total dissolved solids. Concentrations of aluminum, antimony, ferrous iron, molybdenum, and thallium were below detection in the two available samples. Copper and manganese were detected in low amounts, with mean concentrations of 0.005 mg/L and 0.01 mg/L, respectively. Dissolved uranium concentration range from 0.0023 mg/L to 0.0127 mg/L with a mean concentration of 0.00599 mg/L, while dissolved radium-226 range from 0.04 pCi/L to 10.7 pCi/L with a mean concentration of 0.625 pCi/L. (iii) Water Quality in Shallow Bedrock Water quality data for shallow bedrock is available from monitoring well MW 11 which is installed in the bedrock on the hillside above the mine. Monitoring well MW 11 was drilled to 200 ft into bedrock directly above the mine workings (Figure 1-1), and represents background water quality, undisturbed by mining, at that location. Paired monitoring well MW 10 (drilled to 75 ft at the same site) could not be sampled, due to poor completion. Monitoring well MW 11 was sampled ten times between February 1999 and July 2001 and two times in 2008. Results indicate that groundwater in the shallow bedrock is calcium-bicarbonate 14 type water with low to moderate dissolved solids and near-neutral to slightly basic pH (Table 9-6). Dissolved uranium averaged 0.244 mg/L with a median value of 0.017 mg/L. Molybdenum concentrations were below detection. • 14 At pH less than 8, bicarbonate can be calculated from total alkalinity using the relationship HCO3 = T.Alk/0.8202 (Hem, 1985). 4109C.090807 Whetstone Associates