ARCHIVED REPORTS_SECOND HALF AND ANNUAL 2010 GW MONITORING RPT

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Diamond Pet Food Processors of Ripon California LLC January 28, 2011 Combined Amoral and Fourth-Ouarter 2010 Groundwater Monitoring Report Page 6 of 8 Mann-Kendall Analysis Mann-Kendall Trend Analysis was perform for all analytes in all wells (Attachment B). Table 5 (following text) presents the results of the trend analyses at the 2% significance level. Trend analyses for TDS show more improvements in water quality in the southeastern part of the site, reflecting application of the higher quality surface or groundwater to the east percolation field. The trend analyses also show more degradation of groundwater quality in the northeastern part of the site,reflecting concentration of constituents from evapotranspiration by the eucalyptus trees,4 and in the southwestern part of the site from the inflow of high TDS water from the City of Ripon's MW WTF. Figure 16 presents contours of the percentages of analytes per well that have stable or decreasing (down) trends. Sludge Monitoring No sludge was produced at the mill during 2010, therefore, sludge monitoring was not performed. Corrective Action Evaluation and Implementation Schedule In order to meet the WQPS adopted by the CVRWQCB for the site (Table 1), DP predecessor Neenah Paper chose to import low TDS (total dissolved solids) South San Joaquin Irrigation District (SSJID) water as the preferred corrective action method for reducing TDS levels in Plant effluent water and groundwater beneath the site.5,6 The water was provided by the City of Ripon and piped from their holding pond located on the north side of their MWWTF ponds. Groundwater-quality modeling predicted that the application of low (<150 mg/L) TDS water in the east percolation field would improve (lower) TDS levels by 100 to 500 mg/L, depending on the location in the subsurface, over a five year time period. Between June 26 and August 16, 2007, approximately 135.6 acre feet (44 million gallons) of low (133 mg/L) TDS water were pumped into DP's east percolation field and allowed to infiltrate into the subsurface. The east percolation field is located between a high TDS plume originating from the bottom of ASB-2 and production wells PW-6 through PW-8. In addition to recharging the semiperched aquifer with low TDS water, the irrigation water had the additional benefit of creating a hydrologic barrier between ASB-2's TDS plume and the,production wells. Improving the quality of water in the vicinity of the production wells ultimately improves the quality of water discharged by the mill as effluent. According to L&A's groundwater model, the infiltration of 67 acre feet of water annually to the east percolation field, over a five year period, will bring TDS levels in the semiperched and upper aquifers into compliance with the site's WQPS. Groundwater quality improved in the immediate vicinity of the east percolation field in the semiperched, upper, and intermediate aquifers following the application of SSJID water.7 a L&A,November 17,2008,Five-Year Water Ovalin,Review Report. s L&A,June 15,2005,Amended Report of Haste Discharge For Disposal Of Plant Effluent Water. 6 L&A,March 31,2006,Addendum To Amended Report of YVaste Discharge For Disposal Of Platt Effluent Water. 'L&A,February 8,2008, Combined 2007 Annual Su nmay Report, 4th-Quarter 3007 Groundwater-Monitoring Report,And Preliminati,Corrective Action Evaluadon, Neenah Paper Compania, Ripon, California. 70107.01 Task 2 Lawrence&Associates R':ICLIENTSI Diamond Per Fotnlsi0/011/7.01-Grutuul water MouitoringlGromidi✓ater Mmiitoring1201012ud 114 f 2fll/llannual-2nd Half 2010 repomdoc