SITE INFORMATION AND CORRESPONDENCE

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Mr. Kirk Williams • - 2 - • 12 August 2008 downgradient of the grid, respectively, and monitoring well E-1, located about 10 feet upgradient. Increasing concentrations observed in E-1 have not yet been observed in PM-1, and reducing conditions are beginning to appear in PM-1. WFS believes that the pilot study evaluation period should be extended another year, to allow evidence of treatment to fully advance to PM-1. WFS proposes to continue quarterly monitoring of the pilot study monitoring wells, and proposes to add analyses for the dechlorination intermediate products 1-chloropropane, 2- chloropropane, and 1-chloro-2-propene to the analyte list, and replace analyses for ethane and ethane with analysis for propene. These changes would provide more detailed information on the intermediate transformation products of 1,2,3-trichloropropane (1,2,3-TCP) during the next year. Regional Water Board staff concur with the proposed extension of the pilot study evaluation period and with the changes to the pilot study monitoring schedule. Regional Water Board staff appreciate the detail and completeness of The Pilot Test Evaluation Report. This pilot study has already demonstrated that a monitoring well placed within the injection area would improve the interpretation of downgradient water quality changes and reduce the associated uncertainty. North and South Pond Investigation Western Farm Service proposes to obtain current information about the distribution of pollutants in the unsaturated zone beneath the ponds. In the North and South Pond Work Plan, WFS proposes to obtain soil samples at 10-foot vertical intervals beneath the pond from a hollow stem auger advanced at an angle from vertical. A groundwater sample will be obtained when groundwater is encountered, expected at about 55 feet below ground surface. This angled approach permits subsurface exploration without damaging the integrity of the pond caps. All samples will be analyzed for nitrate, carbamate/urea compounds, volatile organic compounds, 1,2,3-TCP, and fumigants. The north pond samples will additionally be analyzed for chlorinated herbicides. Since soil samples from the ponds have historically contained high concentrations of Total Kjeldahl Nitrogen, which identifies the presence of both organic nitrogen and ammonium, WFS needs to add ammonium to its analytical suite for all samples. Regional Water Board staff conditionally concur with the proposed North and South Pond Work Plan. WFS needs to add the following analysis to its analytical suite, and notify Regional Water Board staff when the opportunity to observe the drilling occurs. • Soil and groundwater samples from beneath the north and south ponds shall be analyzed for ammonium in addition to the proposed analytes. • Notify Regional Water Board staff when a drilling date has been secured. According to the schedule proposed in the North and South Pond Work Plan, field work can be completed within 60 days of this letter, and an investigation report can be provided 90 days following completion of the field work. Therefore, we look forward to hearing news of field work being conducted in early October and anticipate having the investigative report by 10 January 2009.