May 13, 2009 Mr. Jan Alfson California Regional Water Quality Control Board Fresno Branch Office 1685 E Street Fresno, CA 93706 Subject: Data Gap Work Plan Addendum Hilmar Cheese Company, Hilmar, Merced County, California Dear Mr. Alfson: On behalf of Hilmar Cheese Company (HCC), Jacobson James & Associates, Inc. (JJ&A) submits this Addendum to the Data Gap Work Plan ( Work Plan ) dated March 4, 2009 prepared by JJ&A for the HCC site located in Merced County, California. The objective of the Work Plan and Addendum is to describe the approach by which the identified data gaps will be addressed to complete the environmental investigation and evaluate remedial action alternatives as required by Cleanup and Abatement Order No. R5 2004 0722 (CAO). This Addendum has been organized in accordance with the Staff Memorandum comments attached to the RWQCB April 6, 2009 letter regarding their review of the Work Plan. Comment 1 Constituents of Concern Carbonate and manganese analyses will be conducted on groundwater samples collected pursuant to the Work Plan. Comment 2 Assess Soil Beneath the Primary Lands HCC collects and analyzes soil samples from depths of 6 inches, 2 feet, 4 feet and 6 feet below ground surface (ft bgs) at five locations twice per year and submits this data to the RWQCB (see attached Figure 1 for approximate soil sampling locations). A representative sample results package was provided to the RWQCB for review with regards to assessing soil beneath the
Data Gap Work Plan Addendum, Hilmar Cheese Company, Hilmar CA May 13, 2009 Page 2 of 8 Primary Lands. The RWQCB acknowledged that the soil data would be useable to address this task, but that additional constituents of concern and locations needed to be evaluated. The additional work proposed by this Addendum to assess the soil beneath the Primary Lands is as follows: Have select soil samples (2 and 6 ft bgs) collected by HCC during the next semi annual soil sampling event include testing for constituents as defined in the Work Plan Table 4 1, attached as the Addendum Table 1. Although these samples will not be collected by JJ&A, a JJ&A field geologist will be present during the collection of these soil samples to confirm that the sampling protocol is consistent with the Work Plan and to log the lithology at each boring. Soil samples will be collected from two additional boring locations to characterize soils associated with Primary Lands F and G as shown on the attached Figure 1. Samples will be collected from these locations by JJ&A field staff at depths of approximately 2 ft, 6 ft and 10 ft bgs with the 10 ft sample depth to be confirmed based on depth to water as this sample is to be collected from just below the water table surface. These soil samples will be analyzed for the constituents of concern identified in the Work Plan, see Table 1. Soil samples will be collected from two additional deep borings to compliment the one deep boring proposed in the Work Plan in the center of the Primary Lands. These two additional deep borings will include locations at the northeast and southwest portions of the Primary Lands as shown on Figure 1. The three deep borings will be extended to the bottom of the Corcoran Clay unit. The soil samples from the three deep on site soil borings will be analyzed for the Work Plan identified constituents of concern, and physical and geochemical parameters as presented in the attached Tables 1 and 2. Soil samples will be collected from the vadose zone and aquifer and aquitard units encountered as summarized in Table 3. The purpose of collecting data below the water table will be to support the evaluation of fate and transport processes. The soil samples collected from the two added on site borings for physical and geochemical analyses will replace those proposed in the Work Plan for off site locations
Data Gap Work Plan Addendum, Hilmar Cheese Company, Hilmar CA May 13, 2009 Page 3 of 8 R and P as show on Figure 1. Soil samples will still be collected below the Corcoran Clay at the R and P boring locations for physical and geochemical analyses, however, as the borings at these off site locations will be extended to the D Zone for grab groundwater sampling and it is thus efficient to collect the deeper soil samples at these locations. Comment 3 Piezometer Installations and Water Level Monitoring Temporary piezometers will be installed near wells MW 11 and MW 13 for use in the mounding evaluation as described in the Work Plan. As requested by the RWQCB, these piezometers will be left in place for one year during which time water level measurements will be obtained during the routine monthly events performed per the WDRs to provide seasonal data of potential mounding trends. The temporary piezometers will be abandoned in accordance with Merced County requirements following the year of data collection. Comment 4 Determining Ambient Water Quality Below the Corcoran Clay As requested by the RWQCB, and as discussed in the Work Plan, existing supply wells located north of the site which are properly constructed will be used to provide data on water quality in the aquifer below the Corcoran Clay (i.e., the Lower Aquifer). JJ&A will also identify if there are properly constructed supply wells between the site and the location of the California Groundwater Ambient Monitoring and Assessment (GAMA) program wells that can be used to: (1) expand the Lower Aquifer ambient data set, and (2) evaluate lithological and water quality trends between the site and the GAMA well locations to assist in determining if the GAMA wells correlate with the hydrogeologic unit comprising the Lower Aquifer beneath the HCC site and thus potentially appropriate to use in the Lower Aquifer ambient data set. Comment 5 Assessment of Water Quality Beneath the Corcoran Clay The confirmation of water quality conditions beneath the Corcoran Clay unit is relevant to the current assessment activities and will provide data necessary to support the identification and evaluation of remedial actions. Specifically, water quality data from beneath the Corcoran Clay will confirm if impacts to the Lower Aquifer are localized and associated with improper well construction or if there is a more laterally extensive impact due to groundwater movement through the Corcoran Clay.
Data Gap Work Plan Addendum, Hilmar Cheese Company, Hilmar CA May 13, 2009 Page 4 of 8 Grab groundwater samples will be collected from the B Zone overlying the Corcoran Clay and the C and D Zone aquifers underlying the Corcoran Clay at the boring location in the southwest portion of the Primary Lands shown on Figure 1 as boring J. The exact sample depths will be based on the boring and electronic log (e log) data. Samples will be field screened for electrical conductivity (EC) and samples will be collected for laboratory analysis of the constituent of concerns as defined in the Work Plan and as summarized in the attached Table 1. The vertical profiling of water quality at this location in conjunction with the soil chemical, physical and geochemical analyses will provide data pertinent to assessing the migration extent and potential through the Corcoran Clay. In addition to the collection of Lower Aquifer water quality data at the on site boring location, Lower Aquifer water quality data will be collected from off site locations. As shown on the attached Figure 2, groundwater profiling will be performed at locations northeast (O), south (P, Q and R) and west (K) of the site. At these locations, lithological characterization and e logs will be conducted to the C zone (locations O and Q) or D zone (locations K, P and R) within the Lower Aquifer. Grab groundwater samples will be collected from the water bearing units in the Upper and Lower Aquifers and field screened for EC. If the field EC exceeds the ambient level established for the Lower Aquifer 1, then monitoring wells will be installed in the Lower Aquifer. If the field EC level does not exceed the ambient level then wells will not be constructed in the Lower Aquifer as part of this work scope. The need for additional Lower Aquifer data and/or monitoring wells will then be further evaluated in coordination with the RWQCB. Based on the field EC screening, one or more monitoring wells will be constructed at each of the five locations. The need for multiple wells at a single location to provide for monitoring of various intervals will be based on the field EC results and determined in coordination with the RWQCB. If a Lower Aquifer monitoring well is installed, then the location will most likely be comprised of a minimum of two wells including one screened in the Upper Aquifer. If a Lower Aquifer well is not necessary, then the locations of K and R may only require one well installation to be screened in the Upper Aquifer. 1 Ambient water quality conditions for the Lower Aquifer will be established prior to performing this stage of field work.
Data Gap Work Plan Addendum, Hilmar Cheese Company, Hilmar CA May 13, 2009 Page 5 of 8 Comment 6 Supply Well Data Evaluation As requested by the RWQCB, wells identified for inclusion in the 2008 supply well sampling event that could not be sampled will be evaluated using the existing 2005 sampling data. The evaluation process will be consistent with the weight of evidence approach presented in the August 15, 2008 Supply Well Evaluation Technical Report prepared by JJ&A. Comment 7 Evaluation of Wells IN1 and IN2 HCC samples the combined flow of wells IN1 and IN2 monthly for laboratory analyses and submits the results to the RWQCB in the monthly reports required per the Waste Discharge Requirements (WDRs). The data is presented in table format as Water Well Supply #1 Quality. Review of the table from the last monthly submittal indicates that eight and one half years of data is available to develop trend graphs. It is noted that data is not available for the wells separately and as such trend graphs constructed using this data will reflect the trends of the blended sample. As part of the work scope presented in the Work Plan, discreet samples will be collected from IN1 and IN2 using packers to sample water quality in the flow from the Upper Aquifer and Lower Aquifer screened intervals. This information in conjunction with the combined well water quality data should provide data relevant to assessing water quality trends and conditions at the IN1 and IN2 locations. Comment 8 Interim Report As requested by the RWQCB, an Interim Report will be submitted summarizing assessment activities and findings. This report will be in the format of a data deliverable. Schedule Forecast A summary of deliverables associated with implementation of the Work Plan as modified by the RWQCB comments was provided by JJ&A to the RWQCB through correspondence dated April 29, 2009. These deliverable dates have been incorporated into a revision of the schedule forecast presented in the Work Plan as follows.
Data Gap Work Plan Addendum, Hilmar Cheese Company, Hilmar CA May 13, 2009 Page 6 of 8 Activity/Deliverable Duration (1) Projected Start Date Projected Completion Date CVRWQCB Review/Approval of Work Plan Addendum 2 weeks May 14, 2009 May 28, 2009 Prepare and Submit Aquifer Pump Test Approach Technical Memorandum (2) June 8, 2009 Supply Well Impact Evaluation June 8, 2009 Pre mobilization/site Access Activities 2 weeks May 14, 2009 May 27, 2009 Sample Supply Wells 8 weeks May 28, 2009 July 17, 2009 Resurvey Monitoring Wells and Confirm Mounding 2 weeks May 28, 2009 June 8, 2009 Install Piezometers for Mounding Evaluation 2 weeks May 28, 2009 June 8, 2009 EDWLS/Mounding Evaluation 6 weeks June 4, 2009 July 10, 2009 EDWLS/Mounding Evaluation Report 6 weeks July 6, 2009 August 17, 2009 Lower Aquifer Ambient Data Evaluation (Local Supply Wells and GAMA Wells as applicable) 7 weeks May 20, 2009 July 8, 2009 Shallow OnSite Borings and Shallow Ambient Wells 2 weeks July 20, 2009 July 31, 2009 Deep Borings, Geophysical Logging, Groundwater Field Screening, Deep Upper Aquifer Ambient Wells and Plume Sentinel Wells 9 weeks July 27, 2009 September 25, 2009 Soil Properties Laboratory Testing and Data Review 3 week TAT July 20, 2009 October 24, 2009 Soil and Grab Groundwater PCOCs Laboratory Testing and Data Review 12 weeks July 6, 2009 October 24, 2009 Monitoring Well Installation/Development 9 weeks July 27, 2009 September 25, 2009 Monitoring/Sentinel Well Sampling (3) September 31, 2009 October 31, 2010 Monthly Ambient Well Sampling (5 months) 20 weeks September 31, 2009 February 15, 2010
Data Gap Work Plan Addendum, Hilmar Cheese Company, Hilmar CA May 13, 2009 Page 7 of 8 Activity/Deliverable Duration (1) Projected Start Date Projected Completion Date Monitoring/Sentinel Well Laboratory Testing and Data Review 4 weeks October 1, 2009 November 30, 2010 Hilmar Bi Annual Soil Sampling 4 weeks October 1, 2009 October 28, 2009 Interim Progress Report October 26, 2009 Aquifer Pump Test (4) 4 weeks November 2, 2009 November 27, 2009 Data Evaluation and Revised Ambient Conditions Evaluation Technical Memorandum 8 weeks January 4, 2010 February 28, 2010 Assessment and Refined Conceptual Site Model Report (5) February 28, 2010 (5) TAT = turn around time 1. Duration is based on 5 day work weeks. 2. Aquifer Pump Test Approach Technical Memorandum to provide aquifer testing and report submittal schedule. 3. Well sampling to correlate with next scheduled HCC monthly well sampling, which is the beginning of October 2009. 4. Aquifer testing to be performed when irrigation and active pumping season has ended. 5. The Assessment and Refined Conceptual Site Model Report submittal date is estimated based on forecasted completion dates of the preceding tasks. A confirmation of the submittal date will be provided in Fall 2009 when actual task completion dates are better defined. The actual submittal date for the Site Assessment and Refined Conceptual Site Model Report will depend on the completion date for the aquifer test, which is planned to be conducted when the 2009 irrigation season is over. The current projected submission date for the Site Assessment and Refined Conceptual Site Model Report is currently estimated as February 28, 2010. This concludes the Addendum to the Data Gaps Work Plan based on RWQCB comments provided in correspondence dated April 6, 2009. Please feel free to call either of us at (916) 660 9994 or Burt Fleischer with HCC at (209) 656 2271 with any questions.
TABLE 1* SOIL AND GROUNDWATER POTENTIAL CONSTITUENT OF CONCERN ANALYTICAL LABORATORY METHODS AND SAMPLE REQUIREMENTS Hilmar Cheese Company Hilmar, California ANALYTE METHOD PQL (mg/l) GROUNDWATER CONTAINER HOLD TIME Field Filtering Required METHOD PQL (mg/kg) SOIL CONTAINER HOLD TIME Anions EPA 300 EPA 300 Sulfate (SO4) 2 16 oz. White Cap Unpreserved 28 days No 2 Tube or Glass Jar 6 months Chloride (Cl) 1 16 oz. White Cap Unpreserved 28 days No 1 Tube or Glass Jar 6 months Nitrate (NO3 N) 0.2 16 oz. White Cap Unpreserved 48 hours No 0.2 Tube or Glass Jar 6 months Cations EPA 200.7 EPA 6010B Calcium (Ca) 0.1 16 oz. Red Cap HNO3 6 months Yes 10 Tube or Glass Jar 6 months Magnesium (Mg) 0.1 16 oz. Red Cap HNO3 6 months Yes 10 Tube or Glass Jar 6 months Sodium (Na) 1 16 oz. Red Cap HNO3 6 months Yes 10 Tube or Glass Jar 6 months Potassium (K) 2 16 oz. Red Cap HNO3 6 months Yes 50 Tube or Glass Jar 6 months Electrical Conductivity (EC) SM 2510B 1 umho/cm 16 oz. White Cap Unpreserved 28 days No NA NA NA NA Total Dissolved Solids SM2540 C 5 16 oz. White Cap Unpreserved 7 days No NA NA NA NA Total Kjeldahl Nitrogen as Nitrogen (TKN) EPA 351.2 1 16 oz Yellow Cap H2SO4 28 days No EPA 351.2 25 Tube or Glass Jar 6 months Dissolved Iron (Fe) EPA 200.7 0.05 16 oz. Red Cap HNO3 6 months Yes EPA 6010B 5 Tube or Glass Jar 6 months Parameters (ph, temperature, EC, ORP) Field reading NA NA NA No NA NA NA NA * Same as Table 4 1 from Data Gap Work Plan (JJ&A, 2009) Notes: PQL = Practical quantitation limit mg/l = miligrams per liter mg/kg = miligrams per kilogram umho/cm = micromho per centimeter 1 of 1
TABLE 2* PHYSICAL AND GEOCHEMICAL ANALYTICAL METHODS AND SAMPLE REQUIREMENTS Hilmar Cheese Company Hilmar, California Physical/Geochemical Parameter Method Sample Type/Volume Preserve Soil Properties (Vadose Zone) Includes permeability to air (native state, vertical or horizontal orientation), grain and bulk densities, total porosity, air filled porosity, moisture content and pore fluid saturations. API RP40 ASTM D2216 one 2" x 6" tube Chill Hydraulic Conductivity Package (Saturated Zone) Includes native state permeability to water (hydraulic conductivity), vertical or horizontal orientation, grain and bulk densities, total porosity, air filled porosity, moisture content and pore fluid saturations. API RP40 ASTM D2216 ASTM D5084 one 2" x 6" tube Chill Effective (Drainage) Porosity ASTM D425M one 2" x 6" tube Chill Grain Size Analysis (Sieve & Laser) Sieve ASTM D422 500 grams NA Laser ASTM 4464M 500 grams NA Cation Exchange Capacity EPA 9081 < 500 grams Chill Total Organic Carbon Walkley Black 100 grams Chill * Same as Table 4 2 from Data Gap Work Plan (JJ&A, 2009) Page 1 of 1
TABLE 3* SOIL SAMPLING PLAN Hilmar Cheese Company Hilmar, California Soil Sampling Zone Vadose Zone Upper Aquifer A E (1) F & G (2) H (3) I & J (4) K (5) P & R (5) 2 ft interval 10 yes yes yes yes 6 ft interval 10 yes yes yes yes A Zone Aquifer 6 yes yes yes yes A Zone Aquitard 4 yes yes yes B Zone Aquifer 4 yes yes yes Primary Aquitard B Zone Aquitard 10 yes (6) yes (6) yes Lower Aquifer Total Number of Soil Samples Per Zone C Zone Aquifer 3 yes yes C Zone Aquitard 3 yes yes D Zone 3 yes yes TOTAL SAMPLE COUNT 53 Onsite Borings Sample Location Offsite Borings * Revision of Table 3 2 from the Data Gaps Work Plan (JJ&A, 2009) Notes: (1) HCC samples these locations twice per year. The 2' and 6' samples will be analyzed for additional chemical constituents of concern to meet requirements in Table 1 of this Addendum. (2) Samples to be analyzed for potential constituents of concern and geochemistry as summarized in Tables 1 and 2 of this Addendum. (3) Samples to be analyzed for potential constituents of concern as summarized in Table 1 of this Addendum and geochemical parameters as summarized in Table 2 of this Addendum. (4) Samples to be analyzed for potential chemical constituents of concern, geochemical and physical parameters as summarized in Table 1 and Table 2 of this Addendum. (5) Samples to be analyzed for geochemical and physical parameters as summarized in Table 2 of this Addendum. (6) Three samples to be collected from the B Zone Aquitard (Corcoran Clay) representing the top, middle and bottom of the unit. 1 of 1