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Diamond Pet Food&Ripon Cogeneration May 28,2014
<br /> Second-Quarter 2014 Groundwater Monitoring Report Page I of 5
<br /> INTRODUCTION
<br /> This report presents the results of second-quarter 2014 groundwater monitoring performed by
<br /> Lawrence &Associates (L&A) on April 7 and 8, 2014, at Diamond Pet Food Processors of
<br /> Ripon California LLC (DP) and Ripon Cogeneration, LLC (Cogen), 942 South Stockton
<br /> Avenue, Ripon, California(Figure 1). The work was performed in accordance with Waste
<br /> Discharge Requirements (WDR) Order No. R5-2012-0105 for the DP/Cogen site, adopted by
<br /> the California Regional Water Quality Control Board, Central Valley Region (CVRWQCB) on
<br /> 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/Cogen site. All offsite monitoring, domestic, and
<br /> municipal wells were sampled by Stantec for the City of Ripon or Environmental Cost
<br /> Management(ECM) for Nestl6s. Field and laboratory results provided by Stantec and ECM
<br /> were used in the preparation of this report and are presented in Attachment A. L&A, however,
<br /> did not review the Stantec or ECM sampling methods or data for accuracy.
<br /> SECOND-QUARTER 2014 GROUNDWATER MONITORING
<br /> FINDINGS
<br /> On April 7, 2014, a hydrologic divide was present in the west-central portion of the DP/Cogen
<br /> site and in the vicinity of the City of Ripon's waste-water treatment facility(WWTF)ponds and
<br /> fresh-water infiltration pond. The direction of the groundwater gradient north of the divide
<br /> ranged between north-northeast (10°) and north-northwest (350°) at a magnitude of 0.00 13 ft/ft;
<br /> the direction of the gradient south of the divide ranged between south-southeast(170°) and
<br /> south-southwest (240°) at a magnitude ranging between 0.0018 and 0.00053 ft/ft. The direction
<br /> of the gradient in the eastern portion of the DP/Cogen site was generally towards the northwest
<br /> (2950) at a magnitude of 0.00085 ft/ft, however, adjacent to the Stanislaus River the gradient
<br /> was towards the south-southwest(210°) at a magnitude of 0.0005 (Table 2; Figure 2).
<br /> pH concentrations in all monitoring well samples were within the 6.5 to 8.5 standard pH units
<br /> range for DP/Cogen 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/Cogen effluent. The highest TDS concentration was measured
<br /> in well OB-4 (1,900 mg/L) located in the eucalyptus grove in the northeast quadrant of the site
<br /> (Figure 3). The lowest TDS concentration was measured in monitoring well OB-17 (130
<br /> mg/L), located in the southeastern corner of the site along the Stanislaus River.
<br /> Nitrate as nitrogen concentrations in wells OB-5, OB-7, OB-8, OB-19, OB-21, OB-26, and OB-
<br /> 28 exceeded the 10 mg/L limitation for DP/Cogen effluent. The highest nitrate concentrations
<br /> were measured in wells OB-5 (17 mg/L) along the western site boundary and in wells OB-26
<br /> (23 mg/L) and OB-28 (35 mg/L; Table 2)just offsite of the northeastern quadrant of the site.
<br /> 10107.06 Task 2 Lawrence&Associates
<br /> W.-I CLIENTSIDiamond Pet Foods 1010107.01-Groundwater Monitoring)Groundwater Monitoring120M2Q20M2st quarter 2014 report.docx
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