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• 4.0 GROUNDWATER QUALITY AND <br />QUANTITY ASSESSMENT <br />ares~,wna,.a: rc.r:sxaxmn:~.c.¢~xxxaara~~..zxaun.~r ~:xG,m.x::ra.sxxxaa;.:w.:rre' <br />4.1 MINE INFLOWS <br />The Probable Hydrologic Consequences section of the permit anticipates a maximum discharge <br />from the two mines of 410 gpm from 170 acres of mining in the Notch Portal area and 780 acres <br />of mining in the Souih Portal area. This was calculated to be equivalent to 0.07 gpm/acre in the <br />Notch Portal and 0.12 gpm in the South Portal, and anticipated to be derived from the overburden <br />and the Cameo B-seam. Annual inflow studies, which have been conducted over the last twelve <br />years, typically note multiple sources of water, i.e. water coming from the floor, ribs and roof. <br />This is complicated further as flows could be derived from the roof and ribs, and have been <br />collected at the gravitational low point. Alternatively, flows could be derived from either the <br />unmined floor of the coal, or from underlying zones. The following observations came from the <br />1995 Mine Inflow Report. <br />Inflows from Roadside North have increased steadily with increased extension of the workings. <br />Inflows from nine sites in 1995 were 119 gpm, and had a weighted average conductivity of 2288 <br />mg/1, with conductivities ranging from 1640 to 3300 umhos/cm. Most of the inflows were derived <br />from sites 1, 8, and 9, the portal excavation subdrain, the No. 1 East Main Seals and the No. 1 <br />• West Panel at 3 North Main, respectively. Site 1 is the last sump prior to discharge from the thine <br />and directly east and downdip of the old Cameo workings. Monitoring of Site 8 suggests that the <br />sealed No. 1 East Main area, which is the area most downdip in this mine, has flooded completely. <br />Site 9 is located in a newly developed area. <br />Inflows from 26 sites in the Roadside North Mine were =" gpm in 1995, down from a high of <br />284.3 gpm in 1992. Forty-three percent of the water came : um floor and rib seeps in southern, <br />most recently opened portions of the mine, sites 24 - 33. Site 30 was notable because 33.3 gpm <br />were identified as being derived from the floor. Thirty-five percent of the water came from Site <br />5, the No. 2 South Mains sump near the mid-way point of the mine. Eighteen percent of the 1995 <br />inflows were observed at Site 3, discharge from the 2nd West Panel Seals. <br />Inflows collect in the northeast portions of the mine. Inflows appear to be predominantly <br />associated with newer extensions of mine workings and from sealed areas of the mine. The <br />location information collected is so general that it doesn't allow differentiation between separate <br />lithological sources. <br />4.2 GROUNDWATER QUALITY ANALYSES <br />The Rollins Sandstone sites contained sodium bicarbonate waters (Appendix IV1 with elevated <br />salinities, ranging from 1110 - 2270 mg/L total dissolved solids (TDS), low hardness, alkaline pHs <br />• (ranging from 8.2 - 8.7 mg/L) and elevated sodium adsorption ratios, ranging from 21.8 - 76.9. <br />2.597\I4S<ptember 9. 1997 9 <br />