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• Discharges measured at this site axe also affected by the pumping of water from this pond <br />for the truck wash 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 increasing trend. <br />Grassy Creek Drainage. Fouz monitoring sites lie within the Grassy Cxeek drainage: <br />Surface Water Site Sw-52-1, located upstream on Grassy Creek; NPDES Discharge Point 003, <br />also known as the Shop Reservoir or the Northwest Impoundment, located just north of the <br />mine shop area; Surface Water Site SW-S2-2, located approximately 0.1 mile downstream of <br />where NPDES 003 discharges into Grassy Cxeek; and Surface Water Site SW-52-3, which <br />monitors discharges from pre-SMCRA mining areas and is located adjacent to Site SW-S2-2. <br />- Surface Water Site SW-S2-1 (SSG1). This site monitors the upper reaches of Grassy Cxeek <br />which are undisturbed by mining of the Seneca II Mine. Review of the hydrograph of <br />monthly flow measuxementa indicates the lowest peak flow for the past five years. Review <br />of the TDS plot indicates a slightly increasing trend. <br />• - NPDES Discharge point 003 (NPDES3). Hydrographs presented in Appendix D show that flow <br />has increased a[ this site since September 18, 1984, when operation of the truck wash <br />system began. Water is siphoned from the Wedge Impoundment (NPDES 002) into a holding <br />pond. Overflow from the holding pond is diverted into the shop ditch, which flows into <br />NPDES 003. water is pumped from~the holding pond to the wash rack, dzains into a settling <br />pond, and then into the same shop ditch. This operation has increased the flow at NPDES <br />003 while decreasing the flow at NPDES 002. Two other events that affected the long-term <br />hydxograph include the diversion away from NPDES 003 of runoff from an inactive fly ash <br />pit (operated by the Nayden Station power plant) in October, 1980; and the diversion away <br />from NPDES 003 of runoff contained in the Northwest Diversion Ditch (see the Seneca 1I <br />Permit Application, Exhibit 7-7, Surface Water Nydrology Map and also the 1982 Seneca II <br />AHR) in April, 1982. Finally, discharge volumes at the 003 site have been affected by the <br />reductr on in diameter o£ the discharge culvert 136 inches to 6 inches) which occurred on <br />July 19, 1988. No comparison of this yearn' flows to prior years is presented since the <br />operation of the truck wash system tends to greatly influence the flow conditions at Pond ~ <br />003. Review of the TDS plot indicates an increasing trend. <br />• <br />IS <br />