ARCHIVED REPORTS_SECOND QUARTER 2013 GW MONITORING RPT

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Diamond Pet Food&Ripon Cogeneration July 12,2013 Second-Quarter 2013 Groundwater Monitoring Report Page 3 of S The existing wastewater facilities (Sump, Clarifier,ASB-1, ASB -2, and irrigation piping) is used to treat the wastewater through aeration and disperse it. Effluent from the Clarifier is discharged into the two aeration stabilization basins in sequence (ASB-1 then ASB-2). The first pond, ASB-1, is approximately 14-feet deep and is lined; the second, ASB-2, is unlined and approximately 5-feet deep. Effluent from ASB-2 is pumped to 86 acres of fields and orchards around the site. Other ponds on the site (labeled Ponds 1 through 4) are unlined and are used only to contain excess wastewater in case of a system upset or a 100-year-or-greater storm event. RIPON COGENERATION PLANT The Cogen plant routes blowdown through the DP facilities wastewater system. Historic flows (2009 and 2010)were between 200,000 and 300,000 gallons per day. In the fourth-quarter 2012, average flows ranged between 55,788 and 137,444 gallons per day. The most recent (October 2012) TDS value for Cogen flow was 828 mg/L; previously, (20 10) TDS in the Cogen discharge ranged between 500 and 1,200 mg/L. Historically, the Cogen flow was blended with lower TDS paper-mill effluent before being discharged, in sequence, into the two aeration basins (ASB-1 and ASB-2)before being pumped to irrigation and percolation fields around the site for disposal. After the paper mill closed(May 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/RC 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 Nestles USA formerly operated an instant coffee and tea processing plant, located approximately 2,000 feet north of the DP/Cogen 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/Cogen site, and have impacted wells south of the Stanislaus River. Based on the distance of the remediation system's extraction wells from the DP/Cogen site and 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/Cogen wells. The capture zone of the extraction wells, however, may extend beneath the DP/Cogen site. An increase in TDS levels in the treatment system influent might indicate that higher TDS water originating at the DP/Cogen site is being captured by the Nestles' system. 10107.04 Task 2 Lawrence&Associates W.ICLIENTSIDiamond Pet Foods1010107.01-Groundwater MonitoringlGroundwater Monitoring1201312Q201312nd quarter 2013.docx