ARCHIVED REPORTS_COMBINED ANNUAL AND FOURTH QUARTER 2016 GROUNDWATER MONITORING REPORT

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Diamond Pet Food&AltaGas Ripon Energy January 31,2017 Combined Annual and Fourth-Quarter 2016 Groundwater-Monitoring Report Page 2 of 6 ANNUAL AND FOURTH-QUARTER 2016 GROUNDWATER-MONITORING RESULTS FINDINGS On October 10, 2016, the direction of the semiperched groundwater gradient across the DP/Ripon Energy site was generally towards the northwest, ranging between 290° and 3240 at magnitudes ranging between 0.00271 and 0.00091 feet per foot(ft/ft). West of the site, a slight mound was present at the surface of the groundwater in the vicinity of the City of Ripon's WWTF ponds and their fresh water infiltration pond(Table 2; Figure 2). The highest TDS concentration in the semiperched aquifer was measured in well OB-4 (1,400 mg/L) located in the eucalyptus grove in the northeast quadrant of the site (Table 2; Figure 3). The lowest TDS concentration(100 mg/L) was measured in monitoring well OB-17, located in the southeastern corner of the site along the Stanislaus River. Compliance wells OB-4, OB-26 and OB-28 had increasing trends for nitrate; wells OB-26 and OB-28 had increasing trends for EC; and well OB-26 had an increasing trend for chloride (Table 5; 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 aquifer 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.1 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. The reason for the increasing trend in nitrate concentrations in wells OB-4, OB-26, and OB-28 is not clear. Nitrate concentrations have fluctuated in these wells in the recent past from highs of 26.6 mg/L in OB-4 (July 1993), 88 mg/L in OB-26 (July 2008), 200 mg/L and in OB-28 (January 2008)to their current nitrate concentrations of 2.1 mg/L in OB-4, 21 mg/L in OB-26 and 67 mg/L in OB-28. The current nitrate levels in OB-26 and OB-28 are approximately 5 to 15 time higher, respectively, than the 4.5 mg/L average effluent nitrate level in ASB-2 pond water for 2016 (Table 4). Wells OB-26 and OB-28 are consistently hydraulically cross gradient of the DP/Ripon Energy site and the nitrate concentrations in OB-26 and OB-28 probably are not related to the disposal of effluent at the DP/Ripon Energy site. FLOW MONITORING Per WDR Order No. R5-2012-0105, influent water is composed of the wastewater streams from DP and Ripon Energy blended with deionized water and groundwater in the Clarifier. The separate flows are metered and DP staff record the meter readings daily and report flows monthly(Attachment B). Table 3 presents monthly waste water and dilution water flows into the Clarifier. The total recorded flow into the Clarifier in 2016 was 48,775,555 gallons. The maximum monthly influent flow to the Clarifier was 5,033,600 gallons in June. 1 G.S.Jorgensen,Kenneth H. Solomon,and V. Cervinka,March 1993,Agroforestry Systems for On-Farm Drain Water Management. 010107.08 Task 4 Lawrence&Associates W.9CLIENTSIDiamond Pet Foods1010107.01-Groundwater MonitoringlGroundwater Monitoring12016WQAnnua1201614TH QUARTER Annual 2016.doc