|
Diamond Pet Food&Ripon Energy April 23,2018
<br /> First-Quarter 2018 Groundwater-Monitoring Report Page I of 5
<br /> INTRODUCTION
<br /> This report presents the results of first-quarter 2018 groundwater monitoring performed by
<br /> Lawrence &Associates (L&A) on January 2 and 3, 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 /> First-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 /> FIRST-QUARTER 2018 GROUNDWATER MONITORING
<br /> FINDINGS
<br /> On January 2, 2018, the direction of the groundwater gradient across the DP/Ripon Energy site
<br /> was northwest and ranged between 295°to 319° at a magnitudes between 0.00107 and 0.00353
<br /> 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-11, OB-24, OB-25, and OB-28
<br /> exceeded the 800 mg/L limitation for DP/Ripon Energy effluent. The highest TDS
<br /> concentration was measured in well OB-4 (1,300 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-22 (100 mg/L), located in the south central portion of the site between
<br /> ASB-2 and the Stanislaus River.
<br /> Nitrate as nitrogen concentrations in wells OB-1, OB-26, and OB-28 met or exceeded the 10
<br /> mg/L limitation for DP/Ripon Energy effluent. The highest nitrate concentration was measured
<br /> in well OB-28 (55 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 /> Since the facility's conversion to a pet food manufacturing facility, however,plant effluent has
<br /> never exceeded the 800 mg/L effluent limitation for TDS. The elevated TDS levels in the
<br /> 10107.10 Task 1 Lawrence&Associates
<br /> W.-I CLIENTSIDiamond Pet Foods 1010107.01-Groundwater Monitoring)Groundwater Monitoring12018U Q2018U Q quarter 2018 report.docx
<br />
|