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RULE 2 - PERMITS <br />and Little Grassy Creeks. The rate can be estimated using the following equation (Freeze and <br />• Cherry, 1979): <br />Q= K•A•(h —h,)IL <br />where: Q = volumetric flow rate <br />K = vertical hydraulic conductivity <br />A = cross - sectional area of flow (area of alluvium in contact with bedrock) <br />h = head in mined area <br />h1= head in alluvium <br />L = length of flow path from the mine to the alluvium <br />The discharge rate from the mine workings to the alluvium was calculated for steady -state <br />conditions assumed to develop after the mine has filled with water and potentiometric heads have <br />recovered to near pre- mining conditions. The vertical hydraulic conductivity of the overburden <br />between the mine workings and the alluvium is estimated to be 10 " ft/d, from data presented by <br />Williams and Clark (1994). The alluvial aquifer area is estimated to be approximately 3.4 x 106 W, <br />or 78 acres (three 4000 -ft lengths of aquifer averaging 500, 250 and 100 feet wide). The head <br />difference, h -h varies from about 22 to 82 feet, so the average of 52 feet was used. The length of <br />the flow path, L, is approximately 200 feet, the vertical distance between the mine workings and the <br />alluvium. Thus, the calculated average inflow is: <br />Q= K•A-(h —h,)IL <br />• Q = 10 -5 ft/d - 3.4 x 10 ft - ( 52 ft) / 200 ft <br />= 8.8 W/d <br />= 0.046 gpm <br />Given that the measured discharge of spoils springs into the alluvium in the area adjacent to the <br />Seneca II spoils averaged 256 gpm from 2007 to 2008, and about 43 gpm between July and March <br />over the last ten years (Section 2.04.7), the effect of the discharge of 0.046 gpm of poor - quality <br />groundwater from the flooded PSCM workings would not be detectable and would have no <br />discernable effect on the quality of groundwater in the alluvial aquifer or on surface water in the <br />stream. <br />Although the physical and chemical conditions may change slightly after mining, such changes are <br />expected to not migrate far from the mined area. Consequently, the groundwater quality and <br />quantity in the mined area and vicinity are not expected to change significantly because of mining <br />activities. <br />Potential Impacts to Surface Water and Probable Hydrologic Consequences <br />PSCM's planned mining and related activities have the potential to generate temporary impacts to <br />surface water resources. These impacts will typically be localized, being confined to those <br />segments of area drainages directly impacted by mining activities, although in some cases impacts <br />• may have the potential to also affect downstream drainage areas. The primary potential mining - <br />related impacts on surface water resources include: <br />PSCM Permit App. 2.05 -84 Revision 03/05/10 <br />