ARCHIVED REPORTS_SITE CONCEPTUAL MODEL 2009

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ameO an apparent hydraulic mound near the WWTF and Neenah Paper discharge areas. The northeasterly flow direction corresponds with higher pumping rates at wells MW-7 and MW-9, which appear to exert an influence on the movement of groundwater beneath the Study Area. The water level in well M-1 7C1 is approximately 2 feet higher than that measured for M-23C1, and similar to M-20C1, implying a southwesterly flow beneath the WWTF disposal ponds. Reasons for the high water level are unknown, as the highest water levels should occur directly beneath the source for recharge (closer to the WWTF). October 1996 (Figure 21): Only six Intermediate Aquifer monitoring wells were monitored during this event, however, the general flow direction appears to be to the north and northeast. The water level measured for well M-6C1 appears to be creating a local depression in the vicinity of the Site, but no known C-zone groundwater pumping was occurring in this area at this time. January 1996 (Figure 22): Ten monitoring wells were monitored during this event; the general direction of the hydraulic gradient in the Intermediate Aquifer appears to be to the northeast and east towards MW-9 and MW-7. The water level measured for well M-17C1 appears to suggest a hydraulic mound in the potentiometric surface north of the WWTF, but no known source for recharge near this well has been identified to create such a mound. Based on the water level contours drawn in Figure 22, localized groundwater flow appears to have been to the south, from well M-1 7C1 towards well M-23C1. June 1992 (Figure 23): Ten Intermediate Aquifer monitoring wells were monitored during this event; the general flow direction appears to be to the northeast and east towards Site production well N-1, Simpson Paper wells S-4 and S-5, and municipal supply wells MW-9 and MW-7. Monitoring well M-23C1 was not gauged during this event, so the presence of a hydraulic mound in the potentiometric surface north of the WWTF could not be assessed. March 1992 (Figure 24): Eight Intermediate Aquifer monitoring wells were monitored during this event; the general flow direction appears to be to the north and northwest towards Site production well N-1 and municipal supply well MW-4. Monitoring well M-23C1 was not gauged during this event, so the presence of a hydraulic mound in the potentiometric surface north of the WWTF could not be assessed. July 1990 (Figure 25): Eight Intermediate Aquifer monitoring wells were monitored during this event; the general flow direction appears to be to the north with interpreted groundwater flow paths converging on Site production well N-1 and municipal supply well MW-4. Monitoring well M-23C1 was not installed at this time, so the presence of a hydraulic mound in the AMEC Geomatrix, Inc. I:\Doc_Safe\9000s\9837.005\4000 REGULATORY\SCM_01.30.09\1_text\SCM Report Final.doc 42