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2.05.6 (3)(b) <br />• ~ RESPONSE continued <br />• Topsoil will be replaced and vegetation established, <br />causing the on-site water budget to approximate the <br />pre-mining condition. <br />A few acre feet of potential runoff will be retained on-site due <br />to the conversion of the detention ponds into stock ponds. <br />Channel stability should not be measurabley modified by the <br />mining or reclamation activities. No well defined channels will be_ <br />directly impacted by mining. The detention ponds will reduce <br />the occurance of peak flow events (up to a 10-year, 24-hour <br />event) in the upper portions of Hayden Gluch and Dowden -= <br />Gulch. This may reduce the scouring action within the upper i <br />portion of these channels. The relatively small percentage of <br />the drainage being controlled by the detention ponds (which will <br />be converted to retention ponds during reclamation) will cause <br />• the impacts of these structures on the peak flows and low flows <br />in the lower portion of the drainages to be negligible. <br />Water quality in Hayden Gulch and to a lesser degree in Dowden <br />Gulch will be impacted due to: <br />• Slight increase in dissolved solids due to evaporation <br />from the detention ponds. <br />• Slight increase in dissolved solids due to ground water <br />inflow and runoff across the disturbed areas. <br />• Slight changes in pH and sediment loading, which will <br />be controlled (pH between 6.0 and 9.0, sediment under <br />45 mgll) by the on-site treatment facilities. <br />A major increase in the contribution of dissolved solids of <br />Hayden Gulch is not anticipated. Assuming, for purposes of - <br />discussion, that the "worst case" condition of a 50 percent <br />• increase in the dissolved solids content of the runoff from the <br />mined area did occur. This would cause approximately a 3 - __ <br />