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Surface Water Site YSGFS. <br />This site was initially part of the monitoring program for Seneca Coal <br />Company's Yoast Mine, and is now part of the PSCM program. It is in the <br />upper part of Grassy Creek, just below the confluence of the Yoast NPDES <br />Pond 011. Review of the TDS plot indicates a slightly increasing trend, <br />with the peak value occurring in August 2013. <br />Surface Water Site SW -S2-1 (SSG1). <br />This site monitors Grassy Creek upstream of mining at the PSCM. Review <br />of the TDS plot indicates a slightly increasing trend. <br />NPDES Discharge Point 003 (NPDES3). <br />Hydrographs presented in Appendix D show that flow has increased at this <br />site since September 18, 1984, when operation of the truck wash system <br />began. During operation, water was siphoned from the Wadge Impoundment <br />(NPDES2) into a holding pond. Overflow from the holding pond was <br />diverted into the shop ditch, which flows into NPDES3. Water was pumped <br />from the holding pond to the wash rack, drained into a settling pond, <br />and then into the same shop ditch. This operation increased the flow at <br />NPDES3 while decreasing the flow at NPDES2. <br />Other events have affected the long-term hydrograph at NPDES3. They <br />include the diversion away from NPDES3 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 NPDES3 o runoff contained in the Northwest <br />Diversion Ditch (see the Seneca II Permit Application, Exhibit 7-7, <br />Surface Water Hydrology Map and also the 1982 Seneca II AHR) in April <br />1982. Discharge volumes at the site have also been affected by the <br />reduction in diameter of the discharge culvert (36 -inches to 6 -inches) <br />that occurred on July 19, 1988. A smaller volume pump and line from Pond <br />002 to the truck wash was installed in August 2001. The truck wash was <br />last used in 2007. These pump lines, which were siphoning water out of <br />Pond 002, were capped off on July 7, 2010. <br />This year's average flow value, 0.020 cfs, is 86% below the historic <br />(1980-2014) average flow value, 0.140 cfs. This year's below average <br />