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along either migration around the bulkhead or along the fracture network back to the <br />surface and therefore no significant changes in water chemistry. <br />9.3 lmpounded Water at the Terry Tunnel Level <br />Drainage from the Terry Tunnel that will be diverted into the mine workings and <br />potentially impounded by a bulkhead to be placed in the Terry Tunnel is a composite <br />flow of water drainage into the mine workings through surface openings and <br />unsaturated flow through the vadose zone. The only available samples of the Terry <br />Tunnel water are mixes of these sources of water. Table 9 shows the available whole <br />water analyses of Terry Tunnel mine drainage. <br />Integrating the data from the whole water analyses with analyses of metals-only, <br />petrographic data and regional and local geologic information permitted a Terry Tunnel <br />reference water to be modeled. This reference water is descriptive of the water that <br />will likely be impounded by a Terry Tunnel bulkhead and is believed to be <br />representative of, and dominantly controlled by, the flow through natural fractures and <br />unsaturated flow through the vadose zone. The composition of the Terry Tunnel <br />reference is shown in Table 10. This reference water is also a calcium sulfate water <br />but with very reduced bicarbonate concentrations. Both in-situ and when impounded, <br />it is believed to be neutral (pH estimated at 7.01 and reduced (but not as reduced as <br />the American Tunnel water). Although the total dissolved solids concentration is less <br />than that of the American Tunnel reference water, the individual and total metals load <br />~unnylwpltrKi117G 1' Mr 1893. Rpt 63 <br />II:I SI(T10f1 HYDRO-SEARCH <br />