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1981CY = 0.098 cfs " <br />1980CY = 0.990 cfs " <br />This year's average flow value, 0.323 cfs, is 58~ of the historic (1980- <br />2003) average flow value, 0.555 cfs. Flow values at this site are <br />affected by the pumping of water from this pond for the truck wash <br />system and for water trucks (dust control), Pumping for the truck wash <br />system began on September 18, 1984. Review of the TDS plot indicates an <br />increasing trend. <br />Grassy Creek Drainage. Four monitoring sites lie within the Grassy <br />Creek drainage: Site 1, located upstream on Grassy Creek; NPDES <br />Discharge Point 003, also known as the Shop Reservoir or the Northwest <br />Impoundment, located just north of the mine shop area; Site 2, located <br />approximately 0.1 mile downstream of where NPDES 003 discharges into <br />Grassy Creek; and Site 3, which monitors discharges from pre-SMCRA <br />mining areas and is located adjacent to Site 2. <br />- Surface Water Site SW-S2-1 (SSGl). This site monitors Grassy Creek <br />upstream of mining by the Seneca II Mine. It was dry in August through <br />October of this year. Review of the TDS plot indicates a slightly <br />increasing trend. <br />- NPDES Discharge Point 003 (NPDES3). Hydrographs presented in Appendix <br />D show that flow has increased at this site since September 18, 1984, <br />when operation of the truck wash system began. Water is siphoned from <br />the Wadge Impoundment (NPDES 002) into a holding pond. Overflow from <br />the holding pond is diverted into the shop ditch, which flows into NPDES <br />003. Water is pumped from the holding pond to the wash rack, drains <br />into a settling pond, and then into the same shop ditch. This operation <br />has increased the flow at NPDES 003 while decreasing the flow at NPDES <br />002. Two other events that affected the long-term hydrograph include <br />the diversion away from NPDES 003 of runoff from an inactive fly ash pit <br />(operated by the Hayden Station power plant) in October, 1980; and the <br />diversion away from NPDES 003 of runoff contained in the Northwest <br />Diversion Ditch (see the Seneca II Permit Application, Exhibit 7-7, <br />17 <br />