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Diamond Pet Food&Ripon Energy July 14,2017
<br /> Second-Quarter 2017 Groundwater-Monitoring Report Page I of 5
<br /> INTRODUCTION
<br /> This report presents the results of second-quarter 2017 groundwater monitoring performed by
<br /> Lawrence &Associates (L&A) on April 4 and 5, 2017, at Diamond Pet Food Processors of
<br /> Ripon California, LLC (DP) and AltaGas Ripon Energy, Inc. (Ripon Energy), 942 and 944
<br /> South Stockton Avenue, Ripon, California(Figure 1). The work was performed in accordance
<br /> with Waste Discharge Requirements (WDR) Order No. R5-2012-0105 for the DP/Ripon Energy
<br /> site, adopted by the California Regional Water Quality Control Board, Central Valley Region
<br /> (CVRWQCB) on October 4, 2012.
<br /> Second-quarter monitoring consisted of measuring the depth to groundwater in monitoring wells
<br /> OB-1, OB-2, OB-4, OB-5, OB-7, OB-8, OB-11, OB-17, OB-19, OB-21, OB-22, OB-24, OB-25,
<br /> OB-26, and OB-28, collecting groundwater samples from the wells and analyzing the samples
<br /> for temperature,pH, electrical conductivity(EC), turbidity, total dissolved solids (TDS), and
<br /> nitrate as nitrogen.
<br /> Table 1 (following text)presents well descriptions including well names, casing diameter,
<br /> reference point elevation, total depth, screened intervals, and aquifer unit(s).
<br /> L&A sampled the wells located on the DP/Ripon Energy site. All offsite monitoring, domestic,
<br /> and municipal wells were sampled by Stantec for the City of Ripon or ECM Consultants for
<br /> Nestl6s. Field and laboratory results provided by Stantec and ECM Consultants were used in
<br /> the preparation of this report and are presented in Attachment A. L&A, however, did not
<br /> review the Stantec or ECM Consultants sampling methods or data for accuracy.
<br /> SECOND-QUARTER 2017 GROUNDWATER MONITORING
<br /> FINDINGS
<br /> On April 4, 2017, the direction of the groundwater across the majority of the DP/Ripon Energy
<br /> site was towards the northwest(2890 to 304°) at a magnitudes of 0.00129 and 0.00248 ft/ft. In
<br /> the central portion of the site and west of the site, mounds were present in the uppermost
<br /> groundwater unit in the vicinity of ASB-2 the City of Ripon's waste-water treatment facility
<br /> (WWTF)ponds and fresh-water infiltration pond. The mound from the WWTF extended
<br /> eastward onto the western portion of DP/Ripon Energy site (Table 2; Figure 2).
<br /> The pH concentrations in all monitoring wells were within the 6.5 to 8.5 standard pH units
<br /> range for DP/Ripon Energy effluent (Table 2).
<br /> TDS concentrations in groundwater samples OB-4, OB-5, OB-24, OB-25, and OB-28 exceeded
<br /> the 800 mg/L limitation for DP/Ripon Energy effluent. The highest TDS concentration was
<br /> measured in well OB-4 (1,200 mg/L) located in the eucalyptus grove in the northeast quadrant
<br /> of the site (Figure 3). The lowest TDS concentration was measured in monitoring well OB-17
<br /> (120 mg/L), located in the southeastern corner of the site along the Stanislaus River.
<br /> Nitrate as nitrogen concentrations in wells OB-1, OB-5, OB-26, and OB-28 met or exceeded the
<br /> 10 mg/L limitation for DP/Ripon Energy effluent. The highest nitrate concentration was
<br /> measured in well OB-28 (62 mg/L; Table 2)just offsite of the northeastern quadrant of the site.
<br /> CONCLUSIONS
<br /> The past disposal of plant process water by the former paper making facility was responsible for
<br /> some of the elevated TDS levels measured in the semiperched aquifer over most of the site.
<br /> 10107.09 Task 2 Lawrence&Associates
<br /> W.-I CLIENTSIDiamond Pet Foods 1010107.01-Groundwater Monitoring)Groundwater Monitoring1201712Q201 NQ quarter 2017 report.docx
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