Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California

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3 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page i TABLE OF CONTENTS PAGE LIST OF FIGURES...ii LIST OF TABLES...ii LIST OF APPENDICES...ii LIST OF ACRONYMS AND ABBREVIATIONS...iii EXECUTIVE SUMMARY...iv 1.0 INTRODUCTION Objective APPROACH OVERVIEW Groundwater Zones Procedure for Calculating Ambient TDS Concentrations UPPER AQUIFER AMBIENT SAMPLING LOCATIONS AND DATA Shallow Zone Data Quality Upper Aquifer Supply Zone Data Quality DATA EVALUATION AND CALCULATION OF AMBIENT TDS CONCENTRATIONS Shallow Zone Upper Aquifer Supply Zone SUMMARY AND CONCLUSIONS REFERENCES...6-1

4 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page ii LIST OF TABLES Table 2-1 Table 3-1 Table 3-2 Table 4-1 Table 4-2 Well Construction Summary Table Shallow Zone Sample Data Summary Table Upper Aquifer Supply Zone Sample Data Summary Table Shallow Zone Statistical Summary and Ambient TDS Concentration Upper Aquifer Supply Zone Statistical Summary and Ambient TDS Concentration LIST OF FIGURES Figure 1-1 Figure 1-2 Figure 2-1 Figure 3-1 Figure 3-2 Figure 4-1 Figure 4-2 Site Location Map Land Use and Supply Well Locations Procedure for Calculating Ambient Groundwater TDS Concentrations Land Use and Shallow Zone Ambient Sample Locations Decision Tree for Selection of Ambient Well Locations within the Upper Aquifer Supply Zone Trilinear Diagram: Shallow Zone Ambient Locations (pre-eda) Trilinear Diagram: Upper Aquifer Supply Zone Ambient Locations (pre-eda) LIST OF APPENDICES Appendix A Appendix B Appendix C Supply Well Information Evaluation and Summary Table Shallow Zone Statistical Calculations and Probability Plot Upper Aquifer Supply Zone Statistical Calculations and Probability Plot

5 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page iii LIST OF ACRONYMS AND ABBREVIATIONS AB B&C Cal-EPA CAO EC FSP Site ft-bgs EDA FSP HCC HP JJA KJ mg/l ORP QC QA ROWD CVRWQCB SGI SWRCB TID TDS µg/l USA USEPA UTL WDR Ambient Boring Brown and Caldwell California Environmental Protection Agency Cleanup and Abatement Order Electrical Conductivity Field Sampling Plan Hilmar Cheese Facility and associated irrigated lands located in Hilmar, CA feet below ground surface Exploratory Data Analysis Field Sampling Plan Hilmar Cheese Company Hydropunch Jacobson James & Associates Kennedy/Jenks Consultants milligrams per liter Oxidizing reducing potential Quality Control Quality Assurance Report of Waste Discharge Regional Water Quality Control Board, Central Valley Region V The Source Group, Inc. State Water Resources Control Board Turlock Irrigation District Total Dissolved Solids micrograms per liter Underground Service Alert U.S. Environmental Protection Agency Upper Tolerance Limit Waste Discharge Requirement

6 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page iv EXECUTIVE SUMMARY Hilmar Cheese Company (HCC) operates a milk-processing facility located north of the town of Hilmar in Merced County, California (the Site). The Central Valley Regional Water Quality Control Board (CVRWQCB) issued Waste Discharge Requirements (WDRs), Order No , in 1997 to regulate HCC discharge of wastewater to lands identified as the Primary and Secondary lands. In 2004, the CVRWQCB issued Cleanup and Abatement Order No. R (the Order) which required the investigation and potential remediation of impacts from the discharge to lands. HCC submitted a Report of Waste Discharge (ROWD) to the CVRWQCB, dated June 2, 2008 (Kennedy/Jenks Consultants, 2008). The information contained in this ROWD will be used by the CVRWQCB to issue revised WDRs for HCC. Ambient concentrations of total dissolved solids (TDS) in groundwater were statistically determined to provide threshold values against which the Site data can be compared to determine where TDS impacts from the HCC operations can not be statistically distinguished from regional TDS conditions. The ambient TDS concentrations were calculated to represent water quality in two portions of the Upper Aquifer, which is comprised of the A and B water bearing zones overlying the Corcoran Clay unit. An ambient TDS concentration was statistically calculated for the Shallow Zone which is defined as the upper 25 feet of the A Zone. An ambient TDS concentration was also statistically calculated for the Upper Aquifer Supply Zone which is defined as the lower portion of the A Zone and the B Zone, and which supplies wells in the vicinity of the HCC Site with water for irrigation and domestic uses. The ambient TDS concentrations were calculated using a 95% Upper Tolerance Limit approach in accordance with: U.S. EPA Interim Final Guidance, Statistical Analysis of Ground-Water Monitoring Data at RCRA Facilities, February 1989; and California regulations for compliance monitoring at nonhazardous and hazardous waste management facilities as described in the California Code of Regulations (CCR) Title 27 and Title 22, respectively. The ambient TDS concentrations calculated for the Shallow Zone (i.e., upper A Zone) and Upper Aquifer Supply Zone (i.e., lower A Zone/B Zone) are 930 mg/l and 760 mg/l, respectively.

7 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page INTRODUCTION Hilmar Cheese Company (HCC) operates a milk-processing facility located north of the town of Hilmar in Merced County, California (the Site) at the intersection of August Road and Lander Avenue (Highway 165) as shown on Figure 1-1 (the Site). The facility includes a wastewater treatment system to manage the wastewater generated through the manufacturing processes. The discharge from the wastewater treatment system is applied to lands, known as the Primary and Secondary Lands. The Central Valley Regional Water Quality Control Board (CVRWQCB) issued Waste Discharge Requirements (WDRs) Order No in 1997 for the discharge of wastewater from the HCC facility to the Primary and Secondary lands. In 2004, the CVRWQCB issued Cleanup and Abatement Order No. R (the Order) which required the investigation and cleanup of impacts from the discharge to lands. HCC submitted a Report of Waste Discharge (ROWD) to the CVRWQCB, dated June 2, 2008 (Kennedy/Jenks Consultants, 2008). The information contained in this ROWD will be used by the CVRWQCB to issue revised WDRs for HCC. 1.1 Objective The objective of this technical memorandum is to establish ambient concentrations for total dissolved solids (TDS) in groundwater in the vicinity of the Site. The ambient TDS concentrations calculated herein are provided as threshold values against which the Site data can be compared to determine where TDS impacts from the HCC operations can not be statistically distinguished from regional TDS conditions.

8 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page APPROACH OVERVIEW An overview of the general approach and rationale used to establish ambient TDS concentrations in groundwater is provided in this section. Detailed descriptions of the data used and statistical methodologies and results are discussed in Sections 3 and Groundwater Zones As described in the Phase II Data Deliverable and Summary Report (JJA, 2008), the groundwater units defined beneath the Site to date include the A and B Zones above the Corcoran Clay and the C and D Zones beneath the Corcoran Clay. The A and B Zones collectively comprise the unconfined and semiconfined units of the Upper Aquifer. This technical memorandum provides calculations of ambient TDS concentrations for: (1) the upper 25 feet of the A Zone referred to herein as the Shallow Zone, and (2) the lower portion of the A Zone and B Zone referred to herein as the Upper Aquifer Supply Zone. The basis for calculating separate ambient TDS concentrations for these zones follows: Shallow Zone Upper Aquifer Supply Zone The Shallow Zone is defined as the upper 25 feet of the water table aquifer (the A Zone). First groundwater is encountered in the vicinity of the Site at approximately five to ten feet below ground surface (ft-bgs). The shallow groundwater receives water from irrigation and is purposefully drained by the TID tile drain system to protect crop root zones from high Supply wells have been installed in the vicinity of the Site to provide water for domestic and irrigation purposes. Supply well locations in the vicinity of the Site are shown on Figure 1-2 and construction details are provided in Table 2-1. As shown in Table 2-1, the total depth and screened interval of the supply wells vary. In general, wells are either installed to obtain water from the 50 to 150 ftbgs interval or from below 150 ft-bgs. These two groupings approximately correlate to installations above or below the Corcoran Clay, their locations are identified on Figure 1-2. The interval providing water to the wells installed above the Corcoran Clay is identified as the Upper Aquifer Supply Zone for purposes of evaluating ambient TDS conditions. This Upper Aquifer Supply Zone includes wells screened in the lower portion of the A Zone and throughout the B Zone. The Shallow Zone is expected to have the most impact from agricultural operations, and the deeper groundwater comprising the Upper Aquifer Supply Zone is expected to have lower ambient TDS levels

9 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page 2-2 due to attenuation effects as groundwater moves vertically through the system. The evaluation of the Shallow Zone and Upper Aquifer Supply Zone TDS data together would thus result in an ambient TDS result that is biased low for purposes of evaluating Shallow Zone conditions and biased high for purposes of evaluating Upper Aquifer Supply Zone conditions. It is for this reason that ambient TDS concentrations have been calculated separately for the Shallow Zone and Upper Aquifer Supply Zones. Details regarding selection of the data sets representing the Shallow Zone and Upper Aquifer Supply Zone are provided in Section 3.0. The data set selection criteria includes land use, well construction, hydrogeologic, geochemical and statistical factors. 2.2 Procedure for Calculating Ambient TDS Concentrations This section describes the procedure for calculating ambient TDS concentrations in the Shallow Zone and Upper Aquifer Supply Zone of the Upper Aquifer. Several steps are necessary to support the quantitative process, from representative data collection and selection to application of various statistical calculations. In accordance with the U.S. EPA Interim Final Guidance, Statistical Analysis of Ground-Water Monitoring Data at RCRA Facilities (February 1989), TDS concentrations were calculated using the 95% Upper Tolerance Limit (95% UTL) approach. The 95% UTL provides a numerical value that incorporates 95% of the expected ambient population, with a 95% degree of confidence. As such, detections of TDS can occur that exceed this value representing the upper 5% of the ambient population. Use of the 95% UTL approach to establish ambient (or background in areas without regional impacts) conditions is consistent with California regulations for compliance monitoring at nonhazardous and hazardous waste management facilities as described in the California Code of Regulations (CCR) Title 27 and Title 22, respectively. The use of the 95% UTL to establish ambient and background concentrations is also described in California guidance for groundwater monitoring and corrective action at permitted hazardous waste facilities (Cal-EPA DTSC, 2001). Example use of the UTL approach for sites regulated under RWQCB orders includes the WDRs issued for the Samoa Class II Waste Disposal site in Humboldt County, California (Order No R ) by the North Coast RWQCB and the WDRs issued for the Grand Island Class III Landfill in Sacramento, California (Order No. R ) by the CVRWQCB. Recent WDRs developed by the CVRWQCB using the UTL approach include the tentative orders for the Jamestown Landfill in Tuolomne County 1 and the Hanford Landfill in Kings County

10 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page 2-3 Because a UTL (or any statistical limit) is directly dependent on the specific set of data used for calculation purposes, the data set must be evaluated for adequacy and representativeness prior to the UTL calculation. This involves the application of exploratory data analysis (EDA), using various geochemical and statistical methods of analysis. Close examination of the ambient data set prior to UTL calculation is important because the inclusion or exclusion of a single data point has the potential to significantly affect the calculated concentration; therefore a technically balanced approach must be applied to the data selection process, with an understanding that a range of ambient concentrations can be obtained, depending on the up-front assumptions and decisions affecting inclusion/exclusion of particular data points. Figure 2-1 outlines the process used for this study to calculate ambient concentrations for TDS using 95% UTLs. A detailed description of the process outlined in Figure 2-1 is provided below. 1. Identify Potential Ambient Sampling Locations this involves the use of professional judgment to select potential ambient sampling locations within the study area boundary. Multiple ambient sampling locations are necessary, distributed both laterally and vertically within the designated ambient sampling area, to provide information on spatial variability and to provide an adequate representation of the ambient TDS population. A. For the Shallow Zone, ambient (AB) locations were identified in the CVRWQCBapproved Phase II Field Sampling Plan (FSP) (SGI, 2007b). These were supplemented with by the CPT-11 data collected in 2007 (SGI, 2007a), as CPT-11 was installed in the AB area. Two Shallow Zone well locations (well MW-20 and MW-21) were also included. Well MW-20 has been previously identified by the CVRWQCB as a suitable ambient location and MW-21 was installed in the vicinity of the AB locations. Section 3.1 provides a more detailed discussion of the Shallow Zone sample locations. B. For the Supply Zone, supply wells in the vicinity of the Site were evaluated to determine locations that were suitable for purposes of establishing ambient conditions. This evaluation included review of well construction logs, well locations, associated land use, and geochemical data, as discussed in Section Sample Ambient Locations Laboratory analysis of ambient groundwater samples, followed by data validation and then Exploratory Data Analysis (EDA). The EDA step includes evaluation of chemical signatures using ratio plots such as trilinear and Stiff diagrams, examination of correlations using scatter plots and linear regression, and inspection of data distributions using histograms and probability plots. EDA serves two basic purposes:

11 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page 2-4 A. It supports a decision on the representativeness and consistency of the ambient data set, and provides information on potential biases. For example, since statistical analysis will be used to calculate an upper concentration threshold, it is important to identify whether or not multiple data populations appear in the data set, possibly as indicated by different groundwater geochemical signatures. Ideally, the ambient data set will exhibit a defined geochemical signature indicative of a single data population, or multiple signatures that can be treated as separate data sets (e.g., multiple ambient sets perhaps reflective of different populations as a function of geography, depth, or lithology). Through EDA, anomalous geochemical signatures can be identified and evaluated for possible exclusion from statistical analysis/ambient concentration calculation. B. It can be used to examine the potential effectiveness of other chemical constituents as indicator parameters, to be used in conjunction with TDS for the identification and delineation of Site-related groundwater impacts. 3. Define Ambient Data Set(s) Group TDS data using results of EDA and professional judgment; proceed with statistical analysis of ambient TDS data set as follows: A. Calculate/depict basic statistical parameters for ambient data set(s) ~ mean; ~ standard deviation; ~ coefficient of variation; and ~ probability plot. All locations had detections of TDS; hence, treatment/adjustment of non-detected values for statistical calculation purposes is not addressed herein. B. Perform statistical outlier testing of ambient data set(s) ~ Dixon s test for data set with number of data points n < 25; (Gibbons, 1994; ASTM, 1998; USEPA, in preparation); or ~ Rosner s test for n > 25; (Gibbons, 1994; EPA, in preparation) If outliers are present, attempt to understand the cause of the outlier. An outlier that presents itself statistically and without any identifiable cause related to geochemical variability, or error related to the sampling, analysis, and data reporting process, must be carefully evaluated. It is possible that a statistical outlier is simply an extreme value

12 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page 2-5 within the sample population and, therefore, provides important information on the sample population. Upon completion of the outlier evaluation, remove any outliers from the data set that are suspected to be not representative of the sample population before proceeding with statistical analysis. C. Perform distributional testing of ambient data set ~ Shapiro-Wilk test for n < 50 (Gibbons, 1994; ASTM, 1998; EPA, 1992); or ~ Shapiro-Francia test for n > 50 (Gibbons, 1994; EPA, 1992) 4. Perform calculation of upper tolerance limit (UTL) (EPA, 1989; EPA, 1992) A. normal-based parametric UTL; or B. lognormal-based parametric UTL; or C. nonparametric UTL. Prior to UTL calculation, it is necessary to address the results of distributional testing (Step 3.C., above) and determine the appropriate approach (i.e., parametric vs non-parametric calculation). Parametric analysis using a UTL provides an inferential limit based on a calculation that relies on a specific assumption regarding the distribution of the data (in this case, normal or lognormal). Alternatively, non-parametric analysis using a UTL makes no assumptions regarding mathematical distribution of the data. A non-parametric model differs from a parametric model in that the model structure is not specified a priori but is instead determined from data. The term nonparametric is not meant to imply that such a model completely lacks parameters but that the number and nature of the parameters are flexible and not fixed in advance. A nonparametric test has less statistical power than a parametric test, but is generally more robust when the distributional assumption underlying the parametric test is not satisfied. In practice, the procedure for determining the most appropriate UTL calculation approach is as follows: If the data set is normally distributed, then no transformation of the data is needed and a parametric UTL can be calculated using the following formula: UTL = X + K*S Where: X = mean of the data set S = standard deviation of the data set

13 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page 2-6 K = one-sided normal tolerance factor (from Table 5, Appendix B of EPA, 1989). If the data set is not normally distributed, then the data set is transformed using natural logarithms and re-testing for lognormality using the Shapiro-Wilk test or the Shapiro- Francia test, depending on the number of data points (n) in the ambient data set. If the data set is lognormally distributed, then parametric analysis of the log-transformed data can proceed using the above formula. All calculations are performed using log normal transformed data; the UTL can be converted back to a linear result using the antilogarithm (EPA, 1989). If the data set is neither normally nor lognormally distributed, then non-parametric analysis of the data is calculated as follows: Non-Parametric UTL = C [max] (EPA, 1992) Where C [max] is the maximum concentration in the ambient data set, provided n>59. With n>59, the nonparametric 95% UTL will provide at least 95% coverage (Gibbons, 1994). However, with n<59, a coverage of less than 95% is provided.. In this case, a normal-based UTL should be calculated in addition to the nonparametric UTL and professional judgment applied to determine which UTL value provides the best estimation of the ambient concentration.

14 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page UPPER AQUIFER AMBIENT SAMPLING LOCATIONS AND DATA This section describes the sampling locations and chemistry data collected for the Shallow Zone and Upper Aquifer Supply Zone ambient conditions evaluation. This section does not present the final data set used to establish the ambient TDS concentration for each zone. The final data set was determined following the EDA step described in the preceding section and identified in Figure 2-1. The EDA results and final data sets used to calculate the ambient TDS concentration are presented in Section Shallow Zone Shallow Zone ambient boring (AB) sample collection locations were identified in the FSP (SGI, 2007B); approved by the CVRWQCB in correspondence dated December 19, The AB locations were selected to be upgradient of the Site, yet not so far upgradient as to reflect potential impacts from non-hcc sources. The AB locations are shown on Figure 3-1. The AB locations were cored using direct push technology (DPT) and groundwater samples were collected at two depths at each AB location using hydropunch equipment as described in the Phase II Data Deliverable and Summary Report (JJA, 2008). The first AB sample depth interval was 5 10 ft bgs or ft bgs, and the second AB sample depth interval was ft bgs or ft bgs. In addition to the AB locations, CPT-11, well MW-20 and well MW-21 were identified as potential locations to represent Shallow Zone ambient conditions. The well MW-20 location was previously identified by the CVRWQCB in the CAO and other documents as potentially representing ambient conditions. The CPT-11 location was sampled in 2007 in an area upgradient of the Site as a potential ambient location (SGI, 2007a). The CPT-11 results were used to support the selection of the 2008 AB sample locations, which are in the vicinity of CPT-11 as shown on Figure 3-1. The CPT-11 results were also used to select the location for MW-21. The CPT-11 location was sampled in June, 2007 and analyzed for TDS and other constituents as described in the Interim Data Deliverable and Summary Report (SGI, 2007a). The AB and MW-21 locations were sampled March 31 through April 8, 2008 and analyzed for TDS and other constituents in accordance with the FSP (SGI, 2007b). The MW-20 groundwater sample was collected in April 2008 in accordance with the WDRs. The TDS and major anion and cation data collected from the AB, CPT-11, MW-20 and MW-21 locations are summarized in Table 3-1. The data presented in Table 3-1 was further evaluated through the EDA step, as discussed in Section 4.1.

15 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page Data Quality The TDS analyses for the AB, CPT-11 and MW-21 samples were performed by BSK Analytical Laboratories, Inc. (BSK). The laboratory data was reviewed and the data was determined to meet the project data quality objectives as summarized in the Data Validation (DV) memorandums provided as appendices with the Interim Data Deliverable and Summary Report and (SGI, 2007a) and the Phase II Data Deliverable and Summary Report (JJA, 2008). The TDS analysis for the MW-20 sample was performed by BC Laboratories, Inc. (BC) and the data was reported to the CVRWQCB (HCC, 2008). The TDS laboratory data for the April 2008 MW-20 sample event was reviewed and the data was determined to be of acceptable quality. 3.2 Upper Aquifer Supply Zone Ambient sample locations for the Upper Aquifer Supply Zone were not predefined specifically for the purpose of collecting ambient data. As such, a review of existing locations and data was necessary to determine if satisfactory locations and data existed to support an evaluation of ambient TDS concentrations for the Upper Aquifer Supply Zone. More than 100 supply wells are located in the vicinity of the Site, providing water for irrigation and domestic uses. Supply wells within a one-half mile radius of the Site were identified and sampled by Brown & Caldwell (B&C) on behalf of HCC in 2005 as requested by the CVRWQCB and in accordance with the CAO (B&C, 2005). In addition, supply well information and data were included in the 2004 ROWD (B&C, 2004). The well construction and sampling data produced through the 2005 sampling event and 2004 ROWD work were evaluated to determine if there were locations and data representative of water quality in the vicinity of the Site but outside of impact by the Site. The evaluation also considered other wells in the region, which were identified through a general search as presented in the Supply Well Information Evaluation and Summary Table provided in Appendix A. The evaluation indicates that there are locations and data suitable for evaluation of ambient TDS conditions for the Upper Aquifer Supply Zone. Figure 1-2 identifies the supply well locations defined by the 2005 work within a one-half mile radius of the Site and additional location of well DW-D identified by the 2004 ROWD. Figure 1-2 identifies which of these wells are constructed above the Corcoran Clay, which are constructed below the Corcoran Clay and which wells do not have construction logs. Table 2-1 provides a summary of the supply well construction details.

16 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page 3-3 The suitability of the supply well locations and data for use in the ambient conditions evaluation for the Upper Aquifer Supply Zone was determined using the criteria identified in Figure 3-2. As shown in Figure 3-2, well locations excluded from the data set included: wells that were screened below the Corcoran Clay; and wells screened in the Upper Aquifer Supply Zone but located down-gradient and in the vicinity of the Site. The Appendix A table lists the supply wells and presents their well specific information and basis for inclusion or exclusion. As shown in Appendix A, the excluded wells also include those that were located beyond the vicinity of the Site and therefore possibly in a different hydrogeologic regime. The included wells were sampled in 2005 in accordance with the Water Supply Well Sampling Work Plan (B&C, 2005a) and the Supplement to the Water Supply Well Sampling Work Plan (B&C, 2005b) with the exception of well DW-D which was sampled in The 2005 supply well sampling and analytical methods and results were documented in the Water Supply Well Sampling Technical Report (B&C, 2005c). The 2004 DW-D sampling and analytical methods were presented in the 2004 ROWD (B&C, 2004). The TDS and major anion and cation data collected from the selected supply well locations are summarized in Table 3-2. The data from these well locations was then further evaluated as shown on Figure 3-2 (decision tree for selection of ambient well locations within the Upper Aquifer Supply zone) to identify: wells with water quality that produced a geochemical signature inconsistent with the Upper Aquifer Supply zone; and wells with water quality data determined to be statistical outliers. Evaluation of the two criteria above was performed as part of the EDA step as detailed in Section Data Quality The 2005 supply well and 2004 DW-D TDS data were determined to meet the data quality objectives as presented in the 2005 supply well sampling report (B&C, 2005) and the 2004 ROWD (B&C, 2004), respectively.

17 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page DATA EVALUATION AND CALCULATION OF AMBIENT TDS CONCENTRATIONS 4.1 Shallow Zone Table 3-1 summarizes the Shallow Zone TDS data set and concentrations for other chemical parameters. The major cations (potassium [K + ], sodium [Na + ], calcium [Ca 2+ ], and magnesium [Mg 2+ ]) and major anions (sulfate [SO 4 2- ], carbonate [HCO 3 - +CO 3 2- ], and chloride [Cl - ]) typically comprising groundwater 3 were used to depict the groundwater signature of each ambient sample point using a trilinear diagram (Figure 4-1). Note that the locations depicted on Figure 4-1 represent the ambient data set prior to EDA; the final ambient data set used for calculation of the 95% UTL is defined after further evaluation, as described below. Inspection of the anion portion of Figure 4-1 (lower right triangle) indicates that the ambient samples group in a broad zone defined by a carbonate (HCO 3 - +CO 3 2- ) proportion of approximately 50% or greater. The cation portion of the figure (lower left triangle) exhibits a continuous, linear series of highly variable Ca:Mg:Na+K ratios possibly reflecting chemical variability imparted by ion exchange in subsurface soils. Three anomalies are evident on the anion portion of Figure 4-1: HP-AB-05A (12 ft bgs), HP-AB-04 (12 ft bgs), and MW-21, which exhibit carbonate proportions below 50% (and higher chloride and sulfate proportions). Because these three samples appear geochemically anomalous with respect to the overall ambient data set, they are excluded from ambient TDS calculations going forward. Further exploratory analysis of the Shallow Zone ambient data set indicates no systematic difference in the geochemical signatures or TDS concentrations between the two depth zones samples (approximately ft bgs and approximately 25 ft bgs). Statistical analysis indicates that TDS concentrations in both depth zones are normally distributed and exhibit no statistically significant concentration difference (Appendix B). This indicates that ambient TDS concentrations in the Shallow Zone are not depth dependent and that TDS concentrations from all sample depths within this zone can be considered for statistical calculation of a Shallow Zone ambient TDS concentration. 3 Nitrate is typically not depicted on trilinear diagrams because nitrate typically does not comprise a significant proportion of anions in ground However, the concentration of nitrate in these ambient samples is significant. Therefore, the trilinear diagrams do not necessary depict the dominant anionic content for these samples and are used solely to evaluate the consistency of the ambient data set.

18 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page 4-2 Using the procedure outlined on Figure 2-1, outlier testing of the pooled ambient data set (excluding HP-AB-05A at 12 ft bgs, HP-AB-04 at 12 ft bgs, and MW-21) using Dixon s test indicates that the TDS result of 1,300 mg/l from location HP-AB-02 at 25 ft bgs is a statistical outlier (Appendix B). Further evaluation of this sample indicates that it exhibits an unusually high nitrate concentration, which also indicates that it should be considered an outlier. Because this sample does not appear representative of the ambient data set, it is excluded from the determination of the ambient TDS concentration. Table 4-1 provides a statistical summary of the ambient data set, and shows the effect of the exclusion of sample points determined to be statistical outliers or exhibiting anomalous geochemical signatures (i.e., HP-AB-05A at 12 ft bgs, HP-AB-04 at 12 ft bgs, HP-AB-02 at 25 ft bgs, and MW-21. The exclusion of these sample points from the ambient TDS data set results in a more conservative statistically calculated ambient TDS concentration. Appendix B presents a probability plot and results of the Shapiro-Wilk distributional test for the ambient data set. Both the Shapiro-Wilk test and the probability plot indicate a TDS concentration distribution consistent with a normal distribution. Therefore, a normal-based parametric tolerance limit calculation is applied to the final ambient TDS data set, returning a 95% UTL of 930 mg/l (Appendix B and Table 4-1). This is the statistically derived ambient TDS concentration for the upper aquifer shallow-zone groundwater within the study area. 4.2 Upper Aquifer Supply Zone Table 3-2 summarizes the Upper Aquifer Supply Zone TDS data set and concentrations for other chemical parameters. Similar to the Shallow Zone ambient data, a trilinear diagram was prepared to examine the geochemical consistency of the data set (Figure 4-2). Note that the locations depicted on Figure 4-2 represent the ambient data prior to EDA; the final ambient data set used for calculation of the 95% UTL is defined after further evaluation of the data set as described below. Comparison of Figure 4-2 with Figure 4-1 indicates that, overall, the geochemical signature of the ambient groundwater sample data set in the Upper Aquifer Supply Zone is very similar to the geochemical signature of the Shallow Zone ambient data set. One geochemical anomaly (well IN-9) is indicated on Figure 4-2, and no systematic variations are apparent based on sample depth (based on the screened interval for locations where that information is available). Based on these observations, the TDS values from Table 3-2, excluding IN-9, were considered to represent the ambient TDS data set for the Upper Aquifer Supply Zone. Using the procedure outlined on Figure 2-1, outlier testing of the pooled ambient Upper Aquifer Supply Zone data set using Dixons s test indicates no statistical outliers

19 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page 4-3 (Appendix C). This data set was used to statistically calculate an Upper Aquifer Supply Zone ambient TDS concentration, as described below. Table 4-2 provides a statistical summary of the Upper Aquifer Supply Zone ambient data set, and shows the effect of the exclusion of sample point IN-9. The exclusion of this datum has a nominal effect (change of 2 mg/l) on the statistically calculated ambient TDS concentration. Appendix C presents a probability plot and results of the Shapiro-Wilk distributional test for the ambient data set. Both the Shapiro-Wilk test and the probability plot indicate a TDS concentration distribution consistent with a normal distribution. Therefore a normal-based parametric tolerance limit calculation is applied to the TDS data set, returning a 95% UTL of 760 mg/l (Appendix C). This is the statistically derived ambient TDS concentration for the Upper Aquifer Supply Zone groundwater within the study area.

20 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page SUMMARY AND CONCLUSIONS Ambient TDS concentrations were calculated to provide threshold values against which the Site data can be compared to determine where TDS impacts from the HCC operations can not be statistically distinguished from regional TDS conditions. Ambient TDS concentrations were calculated to represent water quality in two portions of the Upper Aquifer, which is comprised of the A and B Zones overlying the Corcoran Clay Unit. An ambient TDS concentration was calculated for the Shallow Zone which is defined as the upper 25 feet of the A Zone. An ambient TDS concentration was also calculated for the Upper Aquifer Supply Zone which consists of the lower portion of the A Zone and the B Zone, and which supplies wells in the vicinity of the HCC Site with water for irrigation and domestic uses. A total of 25 and 18 ambient sample locations were evaluated for the Shallow Zone and Upper Aquifer Supply Zone, respectively. Geochemical and statistical evaluations of these samples identified geochemical anomalies and statistical outliers which were removed from the respective data, resulting in a total of 21 and 17 sample results for the Shallow Zone and Upper Aquifer Supply Zone ambient TDS calculations, respectively. The ambient TDS concentrations were statistically calculated using the 95% UTL approach consistent with federal and state guidance and regulations. The calculated ambient TDS concentrations were as follows: Shallow Zone (i.e., upper A Zone): 930 mg/l Upper Aquifer Supply Zone (i.e., lower A Zone/ B Zone): 760 mg/l

21 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page REFERENCES ASTM, D , Standard Guide for Developing Appropriate Statistical Approaches for Ground-Water Detection Monitoring Programs. Reapproved Brown and Caldwell (B&C), 2005a. Water Supply Well Sampling Work Plan, Hilmar Cheese Company, Hilmar, California. January 27, B&C, 2005b. Supplement to Water Supply Well Sampling Work Plan, Hilmar Cheese Company, Hilmar, California. March 4, B&C, 2005c. Water Supply Well Sampling Technical Report, Hilmar Cheese Company, Hilmar, California. July 11, California EPA Department of Toxic Substances, Guidance Document, Monitoring Requirements for Permitted Hazardous Waste Facilities. July California EPA Department of Toxic Substances, 1995b. Guidelines for Hydrogeologic Characterization of Hazardous Substance Release Sites Gibbons, Robert D., Statistical Methods for Groundwater Monitoring. Wiley Interscience. 286 pages. Hilmar Cheese Company, Monthly Water Quality Monitoring Report, April 2008, Order No May, Jacobson James & Associates, Phase II Data Deliverable and Summary Report, Hilmar Cheese Company, Hilmar, California. June 23, Kennedy/Jenks Consultants, Report of Waste Discharge, Hilmar Cheese Company, Hilmar, California. June 2, The Source Group (SGI), 2007a. Interim Data Deliverable and Summary Report, Hilmar Cheese Company, Hilmar, California. August 31, SGI, 2007b. Phase II Investigation Field Sampling Plan, Hilmar Cheese Company, Hilmar, California. November 30, U.S. Environmental Protection Agency (USEPA), Interim Final Guidance, Statistical Analysis of Ground-Water Monitoring Data at RCRA Facilities. Office of Solid Waste Management Division, U.S. Environmental Protection Agency, Washington, D.C. April.

22 Technical Memorandum, Determination of Ambient TDS Concentrations for the Upper Aquifer Hilmar Cheese Company, Hilmar, California June 23, 2008 Page 6-2 USEPA, Addendum to Interim Final Guidance, Statistical Analysis of Ground-Water Monitoring Data at RCRA Facilities. Office of Solid Waste Management Division, U.S. Environmental Protection Agency, Washington, D.C. June. USEPA, in preparation. Unified Guidance on the Statistical Analysis of Ground-Water Monitoring Data.

23 TABLES

24 Well ID Well Location DWR or County Well Log Year Drilled Well Use TABLE 2 1 WELL CONSTRUCTION SUMMARY TABLE Ambient Conditions Technical Memorandum Hilmar Cheese Company Hilmar, California Depth of Boring (ft bgs) Depth of Well (ft bgs) Well Diameter (inches) Perforated Zone Seal Depth (ft bgs) Seal Material Installed Standing GW (ft bgs) DW Johnson Ave No Log Aquifer Type DW Johnson Ave Domestic / Unconfined DW Johnson Ave No Log DW Johnson Ave No Log DW Lander Ave No Log DW Lander Ave No Log DW 7A 9973 Lander Ave No Log DW Johnson Ave No Log DW 9/IN W. Johnson Ave Dairy bentonite Confined DW Johnson Ave County DO 2004 Domestic DW Johnson Ave No Log DW Johnson Ave Domestic / Unconfined DW Johnson Ave No Log DW Columbus Ave No Log DW Columbus Ave No Log 120 a 6 DW Columbus Ave Domestic Cement 8 Unconfined DW Columbus Ave Domestic Bentonite Unconfined DW Columbus Ave Domestic Bentonite Unconfined DW Columbus Ave No Log 6 Notes: NS = Not sampled NA = Not available ft bgs = feet below ground surface 1 of 7

25 TABLE 2 1 WELL CONSTRUCTION SUMMARY TABLE Ambient Conditions Technical Memorandum Hilmar Cheese Company Hilmar, California Well ID Well Location DWR or County Well Log Year Drilled Well Use Depth of Boring (ft bgs) Depth of Well (ft bgs) Well Diameter (inches) Perforated Zone Seal Depth (ft bgs) Seal Material Installed Standing GW (ft bgs) Aquifer Type DW Columbus Ave No Log DW Columbus Ave Domestic Bentonite 10 Unconfined DW 27A 9072 Columbus Ave Domestic b Cement DW August Ave No Log 6 DW August Ave Domestic c Bentonite 8 Unconfined DW 29A August Ave Domestic Cement 12 DW August Ave No Log DW August Ave Domestic NA 12 Unconfined DW August Ave County DO 2000 Domestic DW August Ave Domestic Bentonite 8 Unconfined DW August Ave No Log 6 DW 35B August Ave No Log 6 DW August Ave No Log DW August Ave No Log DW August Ave Domestic NA 15 Unconfined DW 38B August Ave No Log 6 DW 38C August Ave NA 2005 d 6 DW 38D August Ave NA 2005 d 6 DW 38E off Lander Ave NA Notes: NS = Not sampled NA = Not available ft bgs = feet below ground surface 2 of 7

26 TABLE 2 1 WELL CONSTRUCTION SUMMARY TABLE Ambient Conditions Technical Memorandum Hilmar Cheese Company Hilmar, California Well ID Well Location DWR or County Well Log Year Drilled Well Use Depth of Boring (ft bgs) Depth of Well (ft bgs) Well Diameter (inches) Perforated Zone Seal Depth (ft bgs) Seal Material Installed Standing GW (ft bgs) Aquifer Type DW August Ave No Log DW August Ave Domestic UNK bentonite Unconfined DW August Ave No Log DW W. August Ave Domestic bentonite Unconfined DW Lander Ave No Log DW Lander Ave Domestic NA 14 Unconfined DW Lander Ave /2003 Destroy WELL ABANDONMEN DW Lander Ave No Log DW Lander Ave No Log DW 48 Lander Ave No Log DW Lander Ave No Log DW Lander Ave Irrigation No Seal 12 Unconfined DW Lander Ave No Log DW Lander Ave Domestic Bentonite 36 Confined DW Lander Ave Domestic Bentonite Confined DW Lander Ave Domestic bentonite Unconfined DW Oslo Way No Log DW Oslo Way No Log 6 DW Oslo Way No Log NA Notes: NS = Not sampled NA = Not available ft bgs = feet below ground surface 3 of 7

27 TABLE 2 1 WELL CONSTRUCTION SUMMARY TABLE Ambient Conditions Technical Memorandum Hilmar Cheese Company Hilmar, California Well ID Well Location DWR or County Well Log Year Drilled Well Use Depth of Boring (ft bgs) Depth of Well (ft bgs) Well Diameter (inches) Perforated Zone Seal Depth (ft bgs) Seal Material Installed Standing GW (ft bgs) Aquifer Type DW Oslo Way No Log 6 DW Oslo Way Domestic bentonite 8 DW American Ave Domestic Bentonite DW W. American Ave Domestic NA 20+ NA Unconfined DW American Ave No Log DW Columbus Ave Domestic Bentonite 10 DW Columbus Ave Domestic / No Seal 7.5 Unconfined DW Columbus Ave Domestic bentonite 60 Confined DW Johnson Ave Domestic bentonite Confined DW W. August Ave Domestic Bentonite 16 DW Lander Ave NA /8 NA No Seal 10 Unconfined DW 72 NE Corner Lander Ave/August Ave Destroy DW 74 NE Corner Lander Ave/August Ave Domestic Bentonite 14 DW 75 1/2 mile S. of Johnson Ave on Columbus Ave Domestic Cement 10 Unconfined DW Lander Ave Test DW 78 off Lander Ave Domestic / Tamped Earth 11 Unconfined DW Lander Ave Domestic Bentonite 12 Unconfined DW 80 N.E. Corner Columbus Ave & American Ave Domestic bentonite 35 Confined DW 82/IW 7 T6 R10 S11 NW 1/4 TID Drainage DW 83/IN 8 T6 R10 S 15 NW Corner of NE1/4 of NE1/ Industrial none Notes: NS = Not sampled NA = Not available ft bgs = feet below ground surface 4 of 7

28 TABLE 2 1 WELL CONSTRUCTION SUMMARY TABLE Ambient Conditions Technical Memorandum Hilmar Cheese Company Hilmar, California Well ID Well Location DWR or County Well Log Year Drilled Well Use Depth of Boring (ft bgs) Depth of Well (ft bgs) Well Diameter (inches) Perforated Zone Seal Depth (ft bgs) Seal Material Installed Standing GW (ft bgs) Aquifer Type DW 84/IW 8 T6 R10 S15 NW 1/4 TID Drainage , 14 (telescoping) No Seal 21 DW 86/IW 10 NNW of Columbus Ave & Lander Ave Irrigation No Seal 20 Confined DW 88/IW 12 NE August Ave and , 14 TID 133 Drainage Lander Ave deepened (telescoping) DW 89/IW 13 T6 R10 S15 NE1/4 of SW1/4 of NW1/ Drainage DW 90/IW 14 T6 R10 S10 SW1/4 TID 208A 1946 Drainage , 12 (telescoping) DW 91/IW 15 T6 R10 S10 SW1/4 of , 12 TID 64 Drainage NE1/4 deepened (telescoping) DW 92/IW 16 Lander Ave at Lat Drainage No Seal 13 Unconfined DW 94/IW 18 Canhoto Ranch TID Drainage , 12 ( telescoping) DW Lander Ave Domestic Bentonite 26 DW Johnson Ave Domestic bentonite 14 DW Columbus Ave Domestic Bentonite 13 DW Mi. N of August Ave E of Lander Ave Domestic No Seal 30 Unconfined DW Columbus Ave Domestic Bentonite 13 DW August Ave Domestic Bentonite 8 DW Lander Ave Domestic Bentonite 10 DW Lander Ave Irrigation Bentonite DW Johnson Ave County DO 2003 Domestic bent/cement DW August Ave County DO 2003 Domestic bent/cement DW Lander Ave No Log Notes: NS = Not sampled NA = Not available ft bgs = feet below ground surface 5 of 7

29 TABLE 2 1 WELL CONSTRUCTION SUMMARY TABLE Ambient Conditions Technical Memorandum Hilmar Cheese Company Hilmar, California Well ID Well Location DWR or County Well Log Year Drilled Well Use Depth of Boring (ft bgs) Depth of Well (ft bgs) Well Diameter (inches) Perforated Zone Seal Depth (ft bgs) Seal Material Installed Standing GW (ft bgs) Aquifer Type DW C 9175 Columbus Ave No Log DW D 50 IN 1/IW 6/DW Lander Ave Irrigation Cement IN Lander Ave Industrial Bentonite Composite IN 4/DW Oslo Way Dairy Bentonite Confined IN 4A Oslo Way No Log 1971 (per Silveira) 40? 6 IN 5/DW Lander Ave Dairy Bentonite Confined IN 6/DW 81 August Ave 1.25 miles west of Lander Ave Dairy Cement 13 Unconfined IN 7 Johnson Ave Irrigation Cement 38 IN American Ave County DA 1995 Dairy IN 9A American Ave No Log IW August Ave No Log IW 3/DW Columbus Ave Irrigation No Seal 15 Confined IW 4/DW August Ave Irrigation e Bentonite 11 IW 5/DW Lander Ave Irrigation No Seal 25 Confined IW 9/DW 85 T6 R10 S15 SE1/4 of NW1/4 TID 113A 1957 Drainage , 18 (telescoping) No Seal 6 IW 11/DW 87 Lander Ave and August Ave Irrigation Bentonite 28 Confined IW 17/DW 93 Center of SW1/4 above Lat. 6 Sec Drainage No Seal IW Columbus Ave Irrigation Bentonite 8 Notes: NS = Not sampled NA = Not available ft bgs = feet below ground surface 6 of 7

30 TABLE 2 1 WELL CONSTRUCTION SUMMARY TABLE Ambient Conditions Technical Memorandum Hilmar Cheese Company Hilmar, California IW 20 IW 21 IW 22 Well ID Well Location North bank of Lat 6, SW1/4 of NE1/4 of S10 South bank of Lat 6, 500 ft E of Lander Ave. North bank of Lat 6, 500 ft W of Columbus Ave. DWR or County Well Log Year Drilled Well Use Depth of Boring (ft bgs) Depth of Well (ft bgs) Well Diameter (inches) Perforated Zone Seal Depth (ft bgs) Seal Material Installed Standing GW (ft bgs) No Log No Log No Log Aquifer Type a = Owner believes the well is approx. 120 ft deep. b = Field Sampling Record list 12 inch diameter casing; DWR well completion report list well casing as 6 inch diameter. c = Field Sampling Record list 8 inch diameter casing; DWR well completion report list well casing as 6 inch diameter. d = Owner believes the well was installed in e = Field Sampling Record list 6 inch diameter casing; DWR well completion report list well casing as 12 inch diameter. Notes: NS = Not sampled NA = Not available ft bgs = feet below ground surface 7 of 7

31 Bicarbonate Alkalinity (mg/l) Carbonate Alkalinity (mg/l) Hydroxide Alkalinity (mg/l) Total Alkalinity (mg/l) Ammonia as Nitrogen (mg/l) Biological Oxygen Demand (mg O/L) Chemical Oxygen Demand (mg O/L) Chemical Oxygen Demand (mg/l) Chloride (mg/l) Conductivity (umhos/cm) Dissolved Aluminum (mg/l) Dissolved Arsenic (mg/l) Dissolved Arsenic (ug/l) Dissolved Boron (mg/l) Dissolved Calcium (mg/l) Dissolved Iron (mg/l) Dissolved Magnesium (mg/l) TABLE 3 1 SHALLOW ZONE SAMPLE DATA SUMMARY Ambient Conditions Technical Memorandum Hilmar Cheese Company Hilmar, California Sample ID Sample Date HP AB 10 A 4/8/ < <5.0 HP AB 10 AF 4/8/ < HP AB 25 A 4/8/ <1.0 < <5.0 HP AB 25 AF 4/8/2008 < < HP AB 10 A 4/8/ <1.0 < HP AB 10 AF 4/8/ < HP AB 25 A 4/8/ <1.0 < HP AB 25 AF 4/8/ HP AB 12 A 3/31/ <1.0 < HP AB 12 AF 3/31/2008 < < HP AB 25 A 3/31/ <1.0 < HP AB 25 AF 3/31/2008 < < HP AB 12 A 3/31/ <1.0 < HP AB 12 AF 3/31/2008 < < HP AB 25 A 3/31/ <1.0 < HP AB 25 AF 3/31/ < HP AB 12 A 4/1/ <1.0 < HP AB 12 AF 4/1/ < HP AB 25 A 4/1/ <1.0 < HP AB 25 AF 4/1/ < HP AB 12 A 4/1/ <1.0 < HP AB 12 AF 4/1/2008 < < HP AB 25 A 4/1/ <1.0 < HP AB 25 AF 4/1/ < HP AB 12 A 4/1/ <1.0 < HP AB 12 AF 4/1/ < HP AB 25 A 4/1/ <1.0 < HP AB 25 AF 4/1/ < HP AB 10 A 4/7/ <1.0 < HP AB 10 AF 4/7/ < < HP AB 25 A 4/7/ <1.0 < <1.0 HP AB 25 AF 4/7/ < HP AB 12 A 4/1/ <1.0 < HP AB 12 AF 4/1/ < HP AB 25 A 4/1/ <1.0 < HP AB 25 AF 4/1/ < HP AB 14 A 4/7/ <1.0 < HP AB 14 AF 4/7/ Notes: mg/l = milligrams per liter mg O/L = milligrams of oxygen per liter umhos/cm = micromhos per centimeter ug/l = micrograms per liter MPN/100 mls = Most probable number of colony forming units per 100 milliliters Detections are bolded 1 of 2 Dissolved Manganese (mg/l) Dissolved Potassium (mg/l) Dissolved Sodium (mg/l) Fecal Coliform (MPN/100mLs) Hardness, Total (as CaCO3) (mg/l) Nitrate + Nitrite as N (mg/l) Nitrate/Nitrite as N (mg/l) Nitrate Nitrogen (mg/l) ph (standard units) Phosphorus (mg/l) Total Dissolved Solids (mg/l) Total Fixed Dissolved Solids (mg/l) Total Volatile Dissolved Solids (mg/l) Sulfate (mg/l) Sulfide (mg/l) Total Aluminum (mg/l) Total Boron (mg/l) Total Calcium (mg/l) Total Coliform (MPN/100mLs) Total Iron (mg/l) Total Kjeldahl Nitrogen (mg/l) Total Magnesium (mg/l) Total Manganese (mg/l) Total Organic Carbon (mg/l) Total Potassium (mg/l) Total Sodium (mg/l)

32 Bicarbonate Alkalinity (mg/l) Carbonate Alkalinity (mg/l) Hydroxide Alkalinity (mg/l) Total Alkalinity (mg/l) Ammonia as Nitrogen (mg/l) Biological Oxygen Demand (mg O/L) Chemical Oxygen Demand (mg O/L) Chemical Oxygen Demand (mg/l) Chloride (mg/l) Conductivity (umhos/cm) Dissolved Aluminum (mg/l) Dissolved Arsenic (mg/l) Dissolved Arsenic (ug/l) Dissolved Boron (mg/l) Dissolved Calcium (mg/l) Dissolved Iron (mg/l) Dissolved Magnesium (mg/l) Dissolved Manganese (mg/l) TABLE 3 1 SHALLOW ZONE SAMPLE DATA SUMMARY Ambient Conditions Technical Memorandum Hilmar Cheese Company Hilmar, California Sample ID Sample Date HP AB 25 A 4/7/ <1.0 < <5.0 HP AB 25 AF 4/7/ HP AB 10 A 4/8/ <1.0 < HP AB 10 AF 4/8/ < < HP AB 25 A 4/8/ <1.0 < HP AB 25 AF 4/8/ < HP CPT 14 A 6/20/ <1.0 < HP CPT 14 AF 6/20/2007 < < HP CPT 48 A 6/20/ < HP CPT 48 AF 6/20/2007 < < < HP CPT 60 A 6/20/ < HP CPT 60 AF 6/20/2007 < < < MW 20 4/10/ <2.5 < <0.05 <1.5 < <0.1 <0.05 < < <1 8.4 W MW 21 A 4/8/ <1.0 < < < < < W MW 21 AF 4/8/2008 <0.050 < < < A = Samples were not field filtered. AF = Samples were field filtered. Dissolved Potassium (mg/l) Dissolved Sodium (mg/l) Fecal Coliform (MPN/100mLs) Hardness, Total (as CaCO3) (mg/l) Nitrate + Nitrite as N (mg/l) Nitrate/Nitrite as N (mg/l) Nitrate Nitrogen (mg/l) ph (standard units) Phosphorus (mg/l) Total Dissolved Solids (mg/l) Total Fixed Dissolved Solids (mg/l) Total Volatile Dissolved Solids (mg/l) Sulfate (mg/l) Sulfide (mg/l) Total Aluminum (mg/l) Total Boron (mg/l) Total Calcium (mg/l) Total Coliform (MPN/100mLs) Total Iron (mg/l) Total Kjeldahl Nitrogen (mg/l) Total Magnesium (mg/l) Total Manganese (mg/l) Total Organic Carbon (mg/l) Total Potassium (mg/l) Total Sodium (mg/l) Notes: mg/l = milligrams per liter mg O/L = milligrams of oxygen per liter umhos/cm = micromhos per centimeter ug/l = micrograms per liter MPN/100 mls = Most probable number of colony forming units per 100 milliliters Detections are bolded 2 of 2

33 TABLE 3 2 UPPER AQUIFER SUPPLY ZONE SAMPLE DATA SUMMARY TABLE Ambient Conditions Technical Memorandum Hilmar Cheese Company Hilmar, California Location ID Sample Date Bicarbonate Alkalinity (mg/l) Carbonate Alkalinity (mg/l) Hydroxide Alkalinity (mg/l) Total Alkalinity (mg/l) Ammonia as Nitrogen (mg/l) Chemical Oxygen Demand (mg/l) Chloride (mg/l) Conductivity (uhmos/cm) Hardness, Total (as CaCO3) (mg/l) Nitrate/Nitrite as N (mg/l) Nitrate Nitrogen (mg/l) Nitrite as N (mg/l) Nitrogen, Nitrite (AS N) (mg/l) ph (Ph Units) Phosphorus (mg/l) DW 01 5/26/ <1 <1 180 <1 < <0.1 < < <0.05 <1 22 < DW 05 5/11/ <1 <1 230 < <0.1 < < <0.05 <1 17 < DW 06 5/11/ <1 <1 310 < <0.1 < < <0.05 <1 21 < DW 07 5/17/ <1 <1 350 < <0.1 < <0.05 <1 29 < DW 08 5/17/ <1 <1 240 < <0.1 < < <0.05 <1 23 < DW 12 5/12/ <1 <1 230 <1 < <0.1 < < <0.05 < DW 38 5/13/ <1 <1 200 <1 < <0.1 < < <0.05 <1 18 < DW 40 5/12/ <1 <1 280 <1 < < <0.1 < < <0.05 <1 22 < DW 44 5/19/ <1 <1 290 <1 < < <0.1 < < <0.05 < DW 55 5/11/ <1 <1 310 <1 < <0.1 < <0.05 <1 20 < DW 62 5/26/ <1 <1 120 <1 < < <0.1 < < < <2 63 DW 63 5/25/ <1 <1 220 <1 < < < <0.1 < < < DW 79 5/6/ <1 <1 260 <1 < <0.1 < < <0.05 < DW 103 5/4/ <1 <1 290 <1 < <0.1 < <0.05 < DW 104 5/5/ <1 <1 430 < <0.1 < <0.05 < DW 105 5/11/ <1 <1 210 < <0.1 < < <0.05 <1 15 < DW D 6/24/ < < < IN 09 5/25/ <1 <1 170 <1 < < < <0.1 < <0.05 < Solids, total dissolved (mg/l) Solids, total fixed dissolved (mg/l) Solids, total volatile dissolved (MG/L) Specific Conductance (EC) (uhmos/cm) Sulfate (mg/l) Sulfide (mg/l) Total Aluminum (mg/l) Total Arsenic (ug/l) Total Barium (ug/l) Total Boron (mg/l) Total Calcium (mg/l) Total Iron (mg/l) TOTAL KJELDAHL NITROGEN (mg/l) Total Magnesium (mg/l) Total Manganese (mg/l) Total Organic Carbon (mg/l) Total Potassium (mg/l) Total Sodium (mg/l) Notes: mg/l = milligrams per liter ug/l = micrograms per liter umhos/cm = micromhos per centimeter Detections are bolded 1 of 1

34 TABLE 4-1 SHALLOW ZONE STATISTICAL SUMMARY AND AMBIENT CONCENTRATION LIMIT Ambient Conditions Technical Memorandum Hilmar Cheese Company Hilmar, California Ambient TDS Data Set (excluding geochemical anomalies and statistical outliers) Ambient TDS Data Set (prior to exclusion of geochemical anomalies and statistical outliers) Number of Data Points Mean mg/l mg/l 95% UCL of Mean mg/l mg/l Standard Deviation mg/l mg/l Coefficient of Variation 30% 38% UTL (95% confidence, 95% coverage) 930 mg/l (using normal based UTL) 1,073 mg/l (using normal based UTL) 1,300 mg/l (using non parametric UTL with <95% coverage) Notes: TDS = total dissolved solids mg/l = milligrams per liter UTL = upper tolerance limit UCL = upper confidence limit

35 TABLE 4 2 UPPER AQUIFER SUPPLY ZONE STATISTICAL SUMMARY AND AMBIENT CONCENTRATION LIMIT Ambient Conditions Technical Memorandum Hilmar Cheese Company Hilmar, California Ambient TDS Data Set (excluding geochemical anomalies and statistical outliers) Ambient TDS Data Set (prior to exclusion of geochemical anomalies and statistical outliers) Number of Data Points Mean mg/l mg/l 95% UCL of Mean mg/l mg/l Standard Deviation mg/l mg/l Coefficient of Variation 21% 21% UTL (95% confidence, 95% coverage) 760 mg/l (using normal based UTL) 758 mg/l (using normal based UTL) Notes: TDS = total dissolved solids mg/l = milligrams per liter UTL = upper tolerance limit UCL = upper confidence limit

36 FIGURES

37