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Diamond Pet Food&Ripon Energy October 17,2018
<br /> Third-Quarter 2018 Groundwater-Monitoring Report Page I of 5
<br /> INTRODUCTION
<br /> This report presents the results of third-quarter 2018 groundwater monitoring performed by
<br /> Lawrence &Associates (L&A) on July 9 and 10, 2018, at Diamond Pet Food Processors of
<br /> Ripon California, LLC (DP) and A1taGas 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 /> Third-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 /> Nestles. 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 /> THIRD-QUARTER 2018 GROUNDWATER MONITORING
<br /> FINDINGS
<br /> Mounding was present on the surface of the semiperched aquifer in the vicinity of aeration
<br /> stabilization basin 2 (ASB-2) and offsite in the vicinity of the City of Ripon's Fresh Water Pond
<br /> and waste water treatment facility(WWTF)ponds. The direction of the groundwater gradient
<br /> was away from the mounds in all directions (0°to 360°)before turning towards the north across
<br /> the north portion of DP/Ripon Energy site and north of the City's Fresh Water Pond. The
<br /> magnitude of the gradient across the DP/Ripon Energy site ranged between 0.00049 and
<br /> 0.00077 ft/ft(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-1, OB-4, OB-5, OB-24, OB-25, and OB-28
<br /> exceeded the 800 mg/L limitation for DP/Ripon Energy effluent. The highest TDS
<br /> concentrations were measured in wells OB-4, OB-24 and OB-25 (1,300 to 1,500 mg/L) located
<br /> in the eucalyptus grove in the northeast quadrant of the site and in the southwestern quarter of
<br /> the site (Figure 3). The lowest TDS concentration was measured in monitoring well OB-22
<br /> (100 mg/L), located in the south central portion of the site between ASB-2 and the Stanislaus
<br /> River.
<br /> Nitrate as nitrogen concentrations in wells OB-1, OB-5, OB-26, and OB-28 exceeded the 10
<br /> mg/L limitation for DP/Ripon Energy effluent. The highest nitrate concentration was measured
<br /> in well OB-28 (60 mg/L; Table 2)just offsite of the northeastern quadrant of the site.
<br /> 010107.10 Task 3 Lawrence&Associates
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