|
Diamond Pet Food&Ripon Cogeneration July 12,2013
<br /> Second-Quarter 2013 Groundwater Monitoring Report Page 1 of S
<br /> INTRODUCTION
<br /> This report presents the results of second-quarter 2013 groundwater monitoring performed by
<br /> Lawrence &Associates (L&A) on April 9 and 10, 2013, 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 which was
<br /> 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, on April 9, sampling the wells on April 10, 2013, and analyzing the samples
<br /> for pH, electrical conductivity(EC), total dissolved solids (TDS), and 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 Nestles. 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 2013 GROUNDWATER MONITORING
<br /> FINDINGS
<br /> On April 9, 2013, a northeast-southwest trending ridge was present in the semiperched aquifer
<br /> in the eastern portion of the DP/Cogen site. The direction of the groundwater gradient in this
<br /> area was away from the ridge and ranged between southeast(160°) and northwest(300°) at
<br /> magnitudes between 0.000006 and 0.0017 ft/ft. Along the northern and western portions of the
<br /> site, the direction of the gradient ranged from northeast(35°)to southwest(225°). Mounding
<br /> was present west of the DP/Cogen site in the vicinity of the City of Ripon's waste-water
<br /> treatment facility(WWTF)ponds and their fresh-water infiltration pond, and extended eastward
<br /> to the western portion of the DP/Cogen site (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-1, OB-4, OB-5, OB-8, OB-11, OB-24, OB-25,
<br /> and OB-28 exceeded the 800 mg/L limitation for DP/Cogen effluent. The highest TDS
<br /> concentration was measured in well OB-4 (1,800 mg/L) located in the eucalyptus grove in the
<br /> northeast quadrant of the site (Figure 3). The lowest TDS concentration was measured in
<br /> monitoring well OB-17 (110 mg/L), located in the southeastern corner of the site along the
<br /> Stanislaus River.
<br /> Nitrate as nitrogen concentrations in wells OB-1, OB-5, OB-7, OB-8, OB-19, 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-1 (33 mg/L) and OB-28 (31 mg/L; Table 2).
<br /> 10107.04 Task 2 Lawrence&Associates
<br /> W:I CLIENTSIDiamond Pet Foods 1010107.01-Groundwater Monitoring)Groundwater Monitoring12013 12Q2013 12nd quarter 2013.docx
<br />
|