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 2 of 6 ANNUAL AND 2ND-HALF 2012 GROUNDWATER MONITORING RESULTS THIRD-QUARTER 2012 GROUNDWATER MONITORING FINDINGS On July 9, 2012, mounding was present in the semiperched aquifer(uppermost zone) in the west central portion of the DP site and in the vicinity of the City of Ripon's waste-water treatment facility (WWTF)ponds and their fresh water infiltration pond; the general direction of the gradient was away from the mounds (0°to 360°) at magnitudes ranging between 0.002 and 0.0005 feet/foot (ft/ft; Table 2; Figure 2). FOURTH-QUARTER 2012 GROUNDWATER MONITORING FINDINGS On October 1, 2012, mounding within the semiperched aquifer was present offsite in the vicinity of the City of Ripon's WWTF ponds and their fresh water infiltration pond and extended eastward to the central portion of the DP site. The direction of the gradient was away from the mound(0°to 360°) at magnitudes ranging between 0.002 and 0.003 ft/ft; along the eastern portion of the DP site the direction of the gradient was generally towards the west(255° to 270°) at magnitudes ranging between 0.00037 and 0.0006 ft/ft (Table 3; Figure 3). The highest TDS concentration in the semiperched aquifer was measured in well OB-4 (1,900 mg/L) located in the eucalyptus grove in the northeast quadrant of the site (Figure 4). The lowest TDS concentration was measured in monitoring well OB-17, located in the southeastern corner of the site along the Stanislaus River. Compliance well OB-4 had increasing trends for EC and TDS and well OB-26 had an increasing trend for EC (Table 4; Attachment D). The trends for all other constituents were either nonexistent(stable) or decreasing (improving). CONCLUSIONS The disposal of plant process water by the former paper making facility was responsible for some of the elevated TDS levels measured in the semiperched over most of the site. The elevated TDS levels in the semiperched aquifer in the northeastern quadrant of the site, however, which have been up to three times higher than effluent TDS levels, are likely caused by the eucalyptus trees' concentrating effect on TDS.' The elevated TDS levels observed along the western portion of the site,particularly in the southwest corner of the site, probably reflect the infiltration of higher TDS water originating at the City of Ripon's WWTF encroaching onto the DP site. Overall, however, groundwater quality is generally stable or improving under most of the site. INFLUENT/EFFLUENT MONITORING Between January and October 2012, DP staff performed all influent and effluent monitoring and reporting in accordance with WDR No. 5-01-148. The flows entering aeration stabilization basin(ASB)-1 from the Clarifier and exiting ASB-2 were tested weekly for pH, EC, TDS, DO and freeboard levels recorded. Monthly samples of the inflow into ASB-1 also were analyzed for nitrates, fixed residue, and sulfates and the monthly total volume of effluent pumped out of ASB-2 was recorded. ' Ibid.P. 8. 10107.01 Task 8 Lawrence&Associates W.•1 CLIENTSIDiamond Pet Foods1010107.01-Groundwater Monitoringl Groundwater Monitoring1201214Q201214TH QUARTER Annual 2012.docx