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9.4 Overall Chemistry oflmpounded Water Expected to Move through the Ground- <br />Water System <br />Water within the flooded workings is anticipated to represent a mix of American <br />Tunnel and Terry Tunnel reference waters. At deeper levels, chemistry similar to the <br />American Tunnel reference water is expected to dominate, and at shallower levels the <br />chemistry will be most like the Terry Tunnel reference water. Engineering efforts are <br />being enacted to inhibit turnover within the flooded workings, so uniform mixing is <br />less likely within the mine workings than is a somewhat stratified transition between <br />end members. Further mixing between mine waters, and with ground water, is <br />expected to occur as the water moves through the natural fracture system toward <br />Cement Creek. Modeling of 4:1 and 1:1 (American Tunnel:Terry Tunnel) mixes of the <br />reference waters indicates that much of the metals load is likely to precipitate out of <br />solution within the mine workings, due to reducing conditions. This process is an <br />analog to the natural processes of supergene enrichment of ore bodies. In order to <br />be conservative, this likely precipitation was not permitted, end total metals load was <br />retained. Hence, the modeling may yield a somewhat greater metals load than is <br />expected. <br />1 <br />1 <br />9.5 Anticipated Chemistry o/ Surface Discharge <br />Surface discharge of the compounded water was simulated by equilibrating the <br />reference waters and the two mixes of reference waters to atmospheric <br />concentrations of CO? and OZ and then permitting oversaturated minerals to <br />precipitate. The suite of precipitated minerals, dominantly metal oxides for <br />~unnrlwPltndl27511Me, 7 93 ].RPi 65 <br />Ilal SII~1011 HYDRO-SERRCH <br />