SITE INFORMATION AND CORRESPONDENCE

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Site Investigation Work Plan 15 March 1999 Army National Guard Facility Stockton should, therefore, be investigated for VOCs, SVOCs, heavy metals, BTEX and TPH. The revised Work Plan should include discrete soil sampling at regular intervals (e.g., every 100 feet). The sampling protocol should include collection of surface and subsurface soil samples to an initial depth of 5 feet below ground surface. Surface samples should be collected from the walls and crest of the ditch. 5. Buried Drum Area (Additional Activities) - Inspection of the potential buried drum area in the northeastern quadrant of the facility, revealed that this area is currently used for vehicle and equipment storage. We concur that as an initial step a geophysical survey of this area should be performed to determine the presence or absence of buried drums. The revised Work Plan should include discussion on which geophysical methods will be used for the investigation and which specific areas that will be investigated. Based on the geophysical survey, additional actions may be necessary to address this area of concern. 6. Clarifier Contents (Additional Activities) The Work Plan indicates that the contents of the clarifiers in the OMS and CSMS will be sampled. The revised Work Plan should include a sampling and analysis plan for the contents of these clarifiers. Additional Concerns (OMS) 7. We concur with the potential areas of concern identified in Figure 4 of the Work Plan (i.e. Boring locations B 14, B 15, B 16 and B 17). However, our inspection of the facility revealed that the current storage and handling practices for hazardous waste and hazardous materials may have allowed spillage of hazardous materials and/or waste in numerous areas in and around the ~ OMS building (primarily south of the OMS building). The sampling program should, therefore be expanded to include additional borings. These borings should provide investigation around the OMS building, the hazardous materials storage shed, the unpaved area and the fuel truck storage area(in the unpaved area). 8. Former Diesel and Gasoline USTs: Inspection of this area revealed the location of the USTs and the fuel dispenser area for the USTs. The investigation of this area should be expanded and include, at least one boring in the fuel dispenser area, at least one boring (every 20 linear feet) beneath the piping and, at least two borings (one boring for each UST) at the locations of the former USTs. Proposed Soil Boring and Laboratory Analysis 9. Table 2 of the Work Plan indicates a majority of the proposed boring locations will include sampling for volatile organic contaminants (VOCs), Benzene Toluene, Xylene and Ethylbenzene (BTEX) and MTBE. All locations which include sampling for VOCs should include soil gas sampling instead of soil sampling. It has been our experience that collection and handling of soil samples inherently allows losses of contaminants to occur. Method analyses used in the soil gas surveys should include Environmental Protection Agency (EPA) methods TO-14 (for VOCs) and TO-3 (for BTEX).