SITE INFORMATION AND CORRESPONDENCE

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0California Regional Water Quality Control Board .R�¢ Central Valley Region ; '°"""`d Steven T. Butler,Acting Chair ' Winston H.Hickox Gray Davis Secretaryfor Sacramento Main Office Governor Environmental Internet Address: http://www.swrcb.ca.gov/—rwgcb5 Protection 3443 Routier Road, Suite A, Sacramento,California 95827-3003 Phone(916)255-3000• DoD FAX(916)255-3052 15 March 1999 Major Richard Bradley 9800 Goethe Road Sacramento, California 95826-9101 SITE INVESTIGATION WORK PLAN CALIFORNIA ARMYNATIONAL GUARD FACILITY STOCKTO_N, SAN JOA QUINCOUNTY We have reviewed the Site Investigation Work Plan for the California Army National Guard on Stimson Road in Stockton (Work Plan), submitted 18 December 1999. The purpose of the Work Plan is to collect site investigation data to characterize soil conditions in areas of concern identified during a recent file review-by the National Guards consultant Versar. The facility is divided into four divisions: the Army Aviation and Support Facility (AASF); the Combined Support and Maintenance Shop (CSMS); the Operation and Maintenance Shop (OMS); and the Armor-. The Work Plan identifies three (3) areas of concern at the AASF, nine (9) areas of concern at the CSMS and five (5) areas of concern at the OMS. The National Guards consultant Versar did not identify any areas of concern in the Armory section of the facility. We concur that all the sites identified in the Work Plan should be investigated. However, on our recent site visit to the facility, conducted on 25 February 1999, we identified several additional areas of concern for the AASF, CSMS and the OMS. Specific areas that require additional file review and investigation are discussed below. The Work Plan should be revised to include investigation of these additional areas of concern and should be resubmitted for our review and concurrence. We also have comments on the proposed soil boring and laboratory analysis (discussed in Table 2 of the Work Plan). Typically, at sites that are contaminated by volatile organic compounds (VOCs) a more reliable approach for site characterization is to provide soil gas sampling. Further discussion of this comment is provided below. Additional Areas of Concern (AASF, CSMS and OMS) 1. Sewer Lines Facility records should be located to determine the sanitary and storm sewer line layout for the AASF, CSMS and the OMS. The revised Work Plan should include maps showing the layout of the sewer lines with laterals, sumps and any potential discharge points. The site investigation activities for the sewer lines should determine potential discharge points and to evaluate if these discharge points were used for disposal of contaminants or hazardous substances. If it is determined that the sewer line was used for disposal of contaminants or hazardous substances, a video survey of the sewer line should be performed as part of the site investigation to identify any sewer line deficiencies (e.g. sags, breaks, cracks, root intrusion). After the video survey is performed, an additional (Sewer Line Investigation) California Environmental Protection Agency :tea Recycled Paper