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Surface Water Effects <br />The majority of runoff from disturbed areas within the original permit area during <br />the mine life will be diverted to Sediment Ponds 005 and 006, prior to release off <br />site. Effluent from Ponds 005 and 006 flows to unnamed ephemeral gulches, and <br />ultimately Dry Creek. The majority of runoff from disturbed areas in the south <br />extension area during mine life will be diverted to the Sediment Pond 016/016A <br />series or to Sediment Pond 017, prior to discharge. Effluent from the ponds will <br />flow into Hubberson Gulch, and ultimately Dry Creek. Effects of mining on <br />Hubberson Gulch and Dry Creek will involve changes in quantity and quality, which <br />are further described below. <br />A negligible acreage affected by the extreme eastern extension of the south area pits <br />and the neck pits between the north and south mining areas will drain to Sediment <br />Ponds 009 and 015, and eventually to Sage Creek. Measurable effects on Sage Creek <br />water quality or quantity are not projected, due to the small disturbance acreage and <br />the fact that there will be no spoil water flow to the Sage Creek watershed. <br />The mining and reclamation activities will result in changes to the geomorphic <br />characteristics of ephemeral stream channels within the 005, 006, 016 and 017 <br />drainage basins. Drainage densities and channel frequencies will be reduced, and <br />channel gradients will be slightly increased in some areas; however, the operator has <br />designed and located post -mining drainage channels to minimize erosion, with riprap <br />specified where warranted. <br />During mining operations and until adequate vegetation is established, runoff and <br />erosion rates within the disturbed area will be higher than pre -mining rates. SP <br />calculated runoff and erosion/sediment yield rates from disturbed areas when <br />designing all sediment ponds. (Tab 13). Sediment leaving the site will be controlled <br />to meet effluent limits placed upon sediment pond discharges in SP's Colorado <br />Discharge Permit System permit. Baseline flows in Hubberson Gulch exhibit TSS <br />levels from 5 mg/l to 606 mg/l with an average of 100 mg/l. The total suspended <br />solids increase to Hubberson Gulch that can be attributed to mining is expected to <br />be minimal. Once vegetation is successfully reestablished, the erosion rates are <br />expected to return to the pre -mining level of approximately 140 tons/mit/yr. <br />Sediment ponds will act to control flood flows from the disturbed area. The ponds <br />will regulate flood discharges, minimizing the impact of the floods. The ponds are <br />not expected to significantly reduce the quantity of runoff water available in Dry <br />Creek. The mine area makes up only a small portion of the Dry Creek watershed <br />(0.9%). <br />The major impact of mining will be the development and subsequent discharge to <br />the surface system of spoils aquifer waters. As each successive pit is reclaimed in <br />the Wadge and Wolf Creek/Sage Creek mining areas, a spoils aquifer will begin to <br />develop. The water necessary to recharge these aquifers will be derived from <br />24 <br />