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CALIFORNIA REGIOP WATER QUALITY CONTROL BOARD . ""_"�• CENTRAL VALLEY REGION e 3443 Routier Road, Suite A Sacramento, CA 95827-3003 Phone (916) 25530000 All �� Ply �: 37 FAX (916) 255 Mr. Werner Sicvol BP Oil Company 200 Public Square 7-I Cleveland, Ohio 44114-2375 1 d Ute-} Cal/EPA Pete Wilson, Governor 27 January 1998 COMMENTS O SE II REMEDIAL INVESTIGATION REPORT AND WORK PLAN ADDENDU BP OIL COMPANY/APPLIED AEROSPACE STRUCTURES CO STOCKTON, SAN JOAQUI, — I have reviewed the May 1997 Phase II Remedial Investigation Report and the 18 December 1997 Phase II Remedial Investigation Work Plan Addendum for the BP Oil Company/Applied Aerospace Corporation site in Stockton. The investigation report presents the results of the Phase II investigation which was conducted to characterize the lateral and vertical extent of groundwater contaminated by volatile organic compounds (VOCs); evaluate the site stratigraphy and aquifer properties, and assess the viability of soil vapor extraction (SVE) as a remedial alternative. The work plan addendum provides the scope of work to determine the lateral and vertical extent of VOC contamination in groundwater in the northeast corner of the property. My comments are presented below. I provided these comments to you and your consultant, Mr. Fred Kintzer of Parsons Engineering Science, Inc., at our 15 January 1998 onsite meeting. Phase H Remedial Investigation Report 1. Soil, soil gas, and groundwater plumes should be shown on site maps so that data gaps can be easily discerned. If the data are not amenable to showing plumes due to insufficient data points, scattered results, etc., then the report should so state. Nevertheless, the data should still be presented on site maps. 2. Figure 3 shows a profile of the extent of soil and groundwater contamination. Figure 3 should include the monitoring well and hydropunch sample results which were used to draw the profile. Soil concentrations also should be shown. However, if the figure gets crowded, soil sample results should be shown on a separate sheet. These profiles also should include the SVE wells and soil vapor monitoring wells. 3. In Figure 5, a directional arrow or line should be drawn from each box of sample results to the sample location to clearly identify to which location a particular set of results is referring. 4. A monitoring well is needed north and south of the former hazardous waste storage area to define the lateral extent of the shallow groundwater contamination in these areas. 5. A monitoring well, screened at approximately 70-80 feet below ground surface (bgs), is needed at P-1 to confirm the hydropunch sample results and to monitor the groundwater at this depth interval. 6. A sewer line investigation is needed to determine if there are contaminants in the sewer that may be discharging to soil and groundwater. The investigation consists of taking ambient samples in the manholes upstream and downstream of potential source areas, then flushing the line and resampling the downstream manhole. IRecycled Paper our mission is to preserve and enhance the quality of California's water resources, and ensure their proper allocation and efficient use for the benefit of present and future generations.