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3330 Data Drive Delta Suite i00 oa 1/n/w Rancho Cordova,CA 95670 Environmental 916/638-2085 Consultants,Inc. FAX: 9161638-8385 January 26, 1995 RECEIVED Ms. Marla Guensler LIAR g S j§95 Exxon Company, U.S.A. 9NV1K1?NMtNTAL HEALTH Post Office Box 4032 PERMIT/SERVICES Concord, California 94524-2032 Subject: Quarterly Ground Water Monitoring Report, Fourth Quarter 1994 Exxon Retail Station No. 7-3330 3128 West Benjamin Holt Drive Stockton, California Delta Project No. D093-810 Dear Ms. Guensler: Delta Environmental Consultants, Inc. (Delta), has been authorized by Exxon Company, U.S.A. (Exxon), to conduct quarterly ground water monitoring at Exxon Retail Station No. 7-3330, located at 3128 West Benjamin Holt Drive, Stockton, California. This letter report presents the results of quarterly ground water monitoring and sampling conducted on November 22, 1994. The location of the site is shown in Figure 1 and site features are illustrated in Figure 2. All work conducted at the site by Delta was performed in accordance with the field methods and procedures described in Enclosure A. Ground Water Table Elevations Flow Direction and H dr:iulic Gradient Ground water table elevations were measured in each of the four existing monitoring wells at the site on November 22, 1994. Depths to ground water in the monitoring wells ranged from 12.75 to 13.22 feet below the tops of the well casings. Ground water table measurements are presented in Table 1. A water table contour map constructed from the ground water table elevations recorded on November 22, 1994, is included as Figure 3. The water table contours illustrated in Figure 3 indicate that ground water flowed toward the northeast with a hydraulic gradient of approximately 0.001, which is consistent with the historical ground water flow direction. Subjective Analysis No liquid-phase petroleum hydrocarbons or hydrocarbon sheens were present in the wells during the November 1994 site visit. Ground Water Sampling and Analytical Results Ground water samples were collected using field procedures described in Enclosure A, with the exception of monitoring well MW-5 which was purged using a vacuum truck. Approximately 100 gallons of water were removed from monitoring well MW-5 prior to purging. The vacuum truck used to dewater MW-5 was operated by Crosby and Overton Industrial and Environmental Services who transported the water to a permitted facility. Ground water samples collected from monitoring Providing a Competitive Edge