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STATE OF CALIFORNIA - Environmental Prion Agency PETE WILSON Governor CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD CENTRAL VALLEY REGION .iI_TN 3443 Routier Road, Suite A Sacramento, CA 95827-3098 PHONE: (916) 255-3000 �� 2k P �,� �9 �^' ^ FAX: (916) 255-3015 7 18 August 1994 Mr. John Ewing Leprino Foods P.O. Box 173400 Denver, CO 0002.171-34-30 GROUND WATER INVESTIGATION, LEPRINO FOODS, TRACY, SAN JOAQUIN COUNTY I have reviewed the report entitled Phase 3 Ground Water Assessment Report/Monitoring Well Installation Work Plan submitted by Kleinfelder for the Leprino Foods facility at 2401 MacArthur Drive in Tracy. We received the report on 5 August 1994. The geoprobe investigation conducted in July 1994 has not determined the extent of ground water contamination. We made it clear in our 18 February 1994 letter and during our 14 June 1994 meeting that the extent of both soil and ground water contamination must be determined to nondetectable levels. The geoprobe locations apparently were chosen not to extend beyond the boundaries of the Leprino facility. The extent of hydrocarbon-affected ground water is not bounded by GP-19 to the northwest, GP-17 to the southwest, GP-16 to the southeast, and GP-13 to the northeast, as stated in the report. Ground water at these locations had 460 µg/1 unidentified hydrocarbons (>Cj, 310 ttg/1 unidentified hydrocarbons (>C,), 210 ttg/1 unidentified hydrocarbons (>C,e), and 9.4 µg11 benzene, respectively. Although all of these samples were from geoprobes on the perimeter of the facility, a sample of effluent from the oil/water separator which receives around water and free product from extraction well EW-1 also had hydrocarbons heavier than diesel. In addition to diesel, this sample had kerosene and a hydrocarbon in the motor oil range which did not match the typical motor oil pattern. Also, split samples from the initial geoprobe locations GP-2, GP-3, and GP-5 analyzed by the Board's laboratory had pattern peaks similar to kerosene but which elute later, possibly a light fuel oil. These sample results and the presence of a 10,000-gallon aboveground fuel oil tank at the facility suggest that the unidentified hydrocarbons in the recent geoprobe samples is fuel oil. The proposal to install monitoring wells on the perimeter of the facility will not determine the lateral extent of hydrocarbon contamination to nondetectable hydrocarbon concentrations in the upgradient, sidegradient, or downgradient directions.