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STATE OF CALIFORNIA-Environmental Protectloi :ncy PETE WILSON, Govemor CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD CENTRAL VALLEY REGION " 3443 Routier Road,Suite A Sacramento,CA 95827-3098 r1 44 PHONE:(916)255-3000 FAX:(916)255-3015 ! rpA JUL 0 5 1995 29 June 1995 ENVIRONMENTAL HEALTH PERMIT/SERVICES Mr. Terry Lau Western Division, Naval Facilities Engineering Command Environmental Compliance Group 2, Code 09EC2TL 900 Commodore Drive San Bruno, CA 94066-2402 COMMENTS ON THE REMEDIAL INVESTIGATION WORK PLAN FOR UNDERGROUND STORAGE TANK SITES, NAVAL COMMUNICATION STATION IN STOCKTON, SAN JOAQUIN COUNTY The Department of Toxic Substances Control (DTSC) and the Board have reviewed the May 1995 Remedial Investigation Work Plan for the Former Underground Storage Tanks at the Naval Communication Station, Stockton. Enclosure 1 presents DTSC's comments. My comments are presented below. 1. Page 1-1 of the work plan states that Figure 2 depicts the facility and the site locations. Although Figure 2 shows the facility location, the site locations are either not shown clearly or not shown at all. Figure 2 should be replaced with a well-reproduced and adequately-labeled map. 2. Page 3-2 of the work plan states that for UST Site 816D, the concentrations of the unspecified total petroleum hydrocarbons in the soil at 816D-N and 816D-S were 6,000 mg/kg and 3,000 mg/kg, respectively. The work plan also states that no other constituents were detected above their detection limits. The lab reports included in Appendix A show that detection limits for benzene, toluene, ethylbenzene, and xylenes (BTEX)were 2.5 mg/kg for the first three constituents and 15 mg/kg for xylenes. Page 18 of the Tri-Regional Board Staff Recommendations for Preliminary Investigation and Evaluation of Underground Tank Sites lists the practical quantitation limit (PQL) for BTEX in soils as 0.5 mg/kg. The work plan should provide an explanation for the five- fold increase in the PQL. 3. Page 4-2 of the work plan states that the Phase I field work will consist of soil and ground water sampling and installation of temporary piezometers using the Geoprobe system to define the extent of contamination; Phase II will consist of monitoring well (MW) installation, development, and sampling; and sump sites will not be assessed beyond the Phase I level. If the Phase I investigation for the sump sites shows ground water contamination, then a Phase II investigation also must be conducted at these sites.