SITE INFORMATION AND CORRESPONDENCE

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�•• STATE OF CALIFORNIA PETE WILSON. Governor CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD— CENTRAL VALLEY REGION 3443 ROUTIER ROAD, SUITE A SACRAMENTO. CA 95827-3098 " PHONE: (916) 361-5600 FAX: (916) 361-5686 RECEIVEfi14, AU 6 2 24 August 1992 ENV. IRONMENTAL HEALTH pLRMlfi/SI"rKMO Mr. Richard Laubacher BP Oil Company 4850 East 49t Street r, nh An11)r 1n,n Cleveland, V 1V `t`►1LJ-1V/J REQUEST FOR QUARTERLY GROUND WATER MONITORING AND AN EVALUATION REPORT, BP OIL COMPANY, STOCKTON FACILITY, SAN JOAQUIN COUNTY Thank you for sending us the site assessment work plan and the corresponding site assessment report for the BP Oil Company (formerly Mobil Oil Corporation) Bulk Fuel Terminal in Stockton. We have reviewed these documents. The site assessment report shows soil contamination in B-1-10 [10 parts per million (ppm) total petroleum hydrocarbons/diesel (TPHD)], B-4-10 (50 ppm TPHD) , and W-2-10 [60 ppm TPH/gasoline (TPHG) , 1.4 ppm benzene, 0.4 ppm toluene, 0.4 ppm ethylbenzene, and 0.9 ppm xylene]. The ground water sample results show 0.13 ppm TPHG in monitoring well (MW) 1; 0.15 ppm TPHG, 0.3 ppm TPHD, and 9.1 ppb benzene (average of two samples) in MW 2; 0.31 ppm TPHG and 1.1 ppb toluene in MW 3; and nondetect in MW 4, which was formerly B-1. However, a blind duplicate in MW 4 had a concentration of 0.06 ppm TPHG. You stated during our telephone conversation on 17 August 1992 that these soil and ground water sample results are the only data in BP' s possession and that BP has not taken any samples since installation of the monitoring wells in 1939. Therefore, we request that Br implement a quarterly ground water monitoring program starting this quarter, which runs through 30 September 1992. The monitoring program shall include measurement of ground water elevations referenced to mean sea level , TPHD/G, benzene, toluene, ethylbenzene, and xylene. If it has not been done already, the monitoring wells will have to be surveyed to an established and permanent benchmark prior to measurement of ground water elevations and collection of samples. In reporting, the monitoring data shall be arranged in tables so that the date, constituents, concentrations, and units are readily discernible. The monitor- ing report also shall include an interpretation of results, a ground water contour map which clearly indicates the direction of ground water flow, and isoconcentration maps when applicable.