ARCHIVED REPORTS_COMBINED ANNUAL AND SECOND-HALF 2012 GROUNDWATER MONITORING REPORT 01-31-2013

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Diamond Pet Food Processors of Ripon California LLC January 31,2013 Combined Annual and Second-Half 2012 Groundwater Monitoring Report Page S of 6 2009), the Cogen discharge was blended with water pumped from production well PW-6 before being dispersed to the irrigation fields. CITY OF RIPON The City of Ripon operates a municipal WWTF adjacent to the southwest quadrant of the DP site. The WWTF treats an average of 1.0 million gallons per day(MGD). The system consists of a series of clay-lined ponds with a surface mechanical aeration system to oxygenate the waste water. Treated effluent water is disposed by percolation from 45 acres of disposal ponds. The City is currently under directive from the CVRWQCB to evaluate the impacts of effluent disposal on groundwater quality. NESTLES Nestl6s USA formerly operated an instant coffee and tea processing plant, located approximately 2,000 feet north of the DP site, from 1948 through 1986. Solvents used in the decaffeination process, and their daughter products (trichloroethene, dichloroethene, and vinyl chloride)have impacted soils at the site and groundwater throughout the Ripon area. Nestles' consultant, Environmental Cost Management, currently operates two groundwater-treatment systems in the area to remediate the contaminant plumes. The plumes have impacted the upper and intermediate aquifers along the northern and western portions of the DP site, and have impacted wells south of the Stanislaus River. Based on the distance of the remediation system's extraction wells from DP, 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 influences the hydraulic gradient in DP wells. The capture zone of the extraction wells, however, may extend beneath the DP site. An increase in TDS levels in the treatment system influent would indicate that higher TDS water originating at the DP site is being captured by the Nestles' system. HYDROGEOLOGIC SETTING Geology and hydrogeology of the site and vicinity have been described in detail in previous reports.2 Briefly, the Mill is located in the East San Joaquin Groundwater Basin and is underlain by a sequence of Tertiary- and Quaternary-aged continental deposits of the 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 L&A 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 lower zone from 240 to greater than 300 feet bgs. Permeability in the aquifer zones has been estimated at approximately 525 gpd/ft2; permeability in the confining layers has been estimated at 3.5 gpd/ft2.3 Groundwater movement in the semiperched and upper semiconfined zones in the vicinity of Ripon is generally to the west.4 North of Ripon, groundwater moves to the north. Southwest of Ripon, on the southwest side of the San Joaquin River, groundwater also moves to the north, towards the river. 2 L&A,May 5, 1992,Impacts on Receiving Waters from Discharge at the Simpson Paper Company Facility, Ripon, California. 'Ibid., P.27. 4Ibid., Fig. 3. 10107.01 Task 8 Lawrence&Associates W.•1 CLIENTSIDiamond Pet Foods1010107.01-Groundwater Monitoringl Groundwater Monitoring1201214Q201214TH QUARTER Annual 2012.docx