ARCHIVED REPORTS_FIVE-YEAR WATER QUALITY REVIEW REPORT 11-17-2008

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Five-Year Water-Quality Report November 17,2008 Neenah Paper FR LLC Ripon Mill Page 10 of 19 to remediate the contaminant plumes. The plumes have impacted the upper and intermediate aquifers along the northern and western portions of the NP site. Based on the distance of the remediation system's extraction wells from NP,the volume of water treated by the system (<500 gpm), and the relatively high permeability of the aquifer, it is unlikely that the extraction system would influence the hydraulic gradient in NP wells. The capture zone of the extraction wells, however, may extend beneath the NP site. An increase in TDS levels in the treatment system influent would indicate that higher TDS water originating at the NP is being captured by the system. HYDROGEOLOGIC SETTING Geology and hydrogeology of the site and vicinity has been described in detail in previous reports.' Briefly,the Mill is underlain by a sequence of Tertiary and Quaternary continental deposits (Tulare Formation). These deposits consist of interbedded sands/gravels and silts/clays or mixtures thereof. Four distinct aquifers or zones have been identified beneath the site and have been designated by Lawrence&Associates as the semiperched, upper, intermediate, and lower zones. The semiperched zone is unconfined and occurs from approximately 35 to 60 feet below ground surface (bgs). All other zones are semiconfined to confined. The upper zone occurs from approximately 85 to 110 feet bgs,the intermediate zone from 140 to 225 feet bgs, and the deep zone from 240 to greater than 300 feet bgs. Permeability in the aquifer zones has been estimated at approximately 525 gpd/square foot; permeability in the confining layers has been estimated at 3.5 gpd/square foot.2 The direction of the groundwater gradient in the semiperched and upper semiconfined zones in the vicinity of Ripon is generally to the west.3 North of Ripon,the direction of the groundwater gradient is to the north. Southwest of Ripon, on the southwest side of the San Joaquin River,the groundwater gradient is to the north,towards the river. To illustrate regional groundwater quality in the site vicinity, Text Figures 12 and 13 show TDS concentrations over time for wells MW-1 through MW-6 (the wells with the most available data); Table 1 shows the TDS concentrations in July 2007 for City of Ripon wells MW-1 through MW-9- Over the period 2002 through 2007, TDS in City wells generally was stable,with occasional high and low values; TDS in MW-1, however, showed an overall decreasing trend for the period. 1 Lawrence&Associates,May 5, 1992,Impacts on Receiving Waters from Discharge at the Simpson Paper Company Facility, Ripon, California. Z Ibid., p.27. 3 Ibid., Figure 3. 003044.02 Lawrence&Associates W.-UientsToxRiver-NeenahU year review reports15 Year Review 20081Neenah_5YearReview_Aug2008.doc