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[~ <br />- Surface Water Site SW-S2-1 (SSG1). This site monitors Grassy Creek <br />upstream of mining by the Seneca II Mine. It was dry in September 2006. <br />Review of the TDS plot indicates a slightly 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, 1964, <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. <br />Other events have affected the long-term hydrograph at NPDES 003. They <br />include the diversion away from NPDES 003 of the runoff from an inactive <br />fly ash pit (operated by the Hayden Station power plant) in October 1980 <br />and the diversion away from NPDES 003 of runoff contained in the <br />Northwest Diversion Ditch (see the Seneca II Permit Application, Exhibit <br />7-7, Surface Water Hydrology Map and also the 1962 Seneca II AHR) in <br />April 1982. Discharge volumes at the 003 site have also been affected by <br />the reduction in diameter of the discharge culvert (36 inches to 6 <br />inches) that occurred on July 19, 1968. Finally, a smaller volume pump <br />and line from 002 to the truck wash was installed in August 2001. <br />This year's average flow value, 0.058 cf s, is 39~ of the historic (1980- <br />2006) average flow value, 0.148 cf s. However, the operation of the <br />truck wash system, and the timing of flow measurements, tends to greatly <br />influence the flow values reported. Review of the TDS plot indicates an <br />increasing trend. <br /> - Surface Water Site SW-S2-3 (SSG3). This site monitors discharges from <br /> pre-SMCRA mining areas before they enter Grassy Creek at a point just <br /> below Site SW-S2-2. This site was re-established in June 1997. TDS <br /> values at this site exhibit a stable trend, This site was dry in June <br />17 <br />