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MEMORANDUM CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD - CENTRAL VALLEY REGION 3443 Routier Road, Suite A Phone: (916) 361-5600 Sacramento, CA 95827-3098 ATSS Phone: 8-495-5600 TO: Antonia K. J. Vorster FROM: Camilla Williams Senior WRC Engineer ( Engineering Geologist DATE: 31 January 1992 SIGNATURE: SUBJECT: REVIEW OF THE WORK PLAN FOR REMEDIAL ACTION AT BUILDING 201, DEFENSE DISTRIBUTION REGION WEST (DDRW), TRACY, SAN JOAQUIN COUNTY I have reviewed the Work Plan entitled "Remedial Action at Building 201" for the DDRW, Tracy site. The Work Plan was submitted on 29 January 1992 by International Technology (IT) Corporation. A draft Work Plan entitled "Soil Treatment/Disposal , Building 201, " submitted most recently on 2 December 1991, was also reviewed. One of the major problems with the Work Plan is that the existing data from the 1991 soil sampling at the Building 201 tank excavation were not presented. The Work Plan did not summarize the results of all of the soil samples, did not present the data in tabular and graphical form and did not present the laboratory analytical sheets. Because the existing data were not presented in the Work Plan, it is not possible to evaluate the adequacy of the proposals or to make recommendations for the investigation. DDRW, Tracy should submit the existing soil data. The soils data should be summarized in tabular form and should specify the depth of the samples, the locations of the samples should be depicted on a map of the excavation and the laboratory analytical sheets should be provided. The second major problem was that the Work Plan did not propose any plans for the known soil contamination at the Building 201 tank excavation site. DDRW, Tracy must submit a plan to remediate the fuel contaminated soils. My detailed comments on the Work Plan are listed below. Page 1-2. The only data provided in the Work Plan from the existing data collected by DDRW, Tracy in 1991 are the maximum contaminant concentrations found in tie soil samples. The reported concentrations for gasoline (340 milligrams per kilogram (mg/kg)) , diesel (3900 mg/kg) , benzene (9.3 mg/kg) , toluene (21 mg/kg) , ethyl benzene (2.2 mg/kg) and xylene (13 mg/kg) are very high. These concentrations indicate that the soils must be remediated so that they do not pose a threat to water quality. The submittal did not propose any plans to remediate the fuel contamination in the soils. A plan for remediation of the fuel contaminated soils needs to be submitted. Based on the concentrations and depending on the depth of the soil samples (which are unknown) , floating product could exist at this tank site. If the ground water is determined to be contaminated, then it will need remediation and DDRW, Tracy will need to submit plans for an extraction system and modification of the Interim Remedial Measure (IRM) . Page 1-3. The Work Plan states that the lead concentration found in contaminated soils is as high as 26,000 mg/kg. This concentration exceeds the