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Suite Dai i Dr,t Delta sate 100 Ca '-A� i5t,i environmental q16 y16 6 6 �38 2085085 Consultants,Inc FAX 91(� 038 8 385 December 16, 1993 R1:1%.� FIVED Ms Marla Guensler F E B 2 2 4994 Exxon Company, U S A. ENV1R0N1ftN (AL HEALTH Post office Box 4032 PERMMSERVICES Concord, California 94524-2032 Subject Quarterly Ground Water Monitonng Report, Fourth Quarter 1993 Exxon Retail Station No 7-3708 2705 Country Club Boulevard Stockton, California Delta Project No 40-93-809 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 7-3708, located at 2705 Country Club Boulevard, Stockton, California This letter report presents the results of quarterly ground water monitoring and sampling conducted on November 15, 1993 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 Elevation,_Flow Direction, and Hydraulic Gradient Ground water table elevations were measured in each of the six ground water monitoring wells at the site on November 15, 1993 Depths to ground water in the monitoring wells ranged from 12 33 to 15 00 feet below the tops of the well casings Ground water table elevations have decreased approximately 1 foot since the previous monitoring event in September 1993 Ground water table measurements are presented in Table 1 A water table contour map constructed from the measurements recorded on November 15, 1993, is included as Figure 3 The water table contours indicate that ground water flowed toward the northeast with a hydraulic gradient of approximately 0 001 Last quarter the ground water flow direction was toward the northwest Subjective Analysis No liquid-phase petroleum hydrocarbons or hydrocarbon sheens were present in the wells during the November 1993 site visit Anatytical Results Ground water samples collected from each of the six monitoring wells on November 15, 1993, were submitted to a California-certified laboratory for analysis of benzene,toluene,ethylbenzene,total xylenes (BTEX), and total petroleum hydrocarbons (TPH) as gasoline Analytical test results are summarized in Table 2 Ground water samples collected from monitoring wells MW-2, MW-4, MW-5 and MW-6 did not contain detectable concentrations of benzene A dissolved benzene isoconcentration map based on analytical results for ground water samples collected on November 15, 1993, is included as Figure 4 Copies of the laboratory analytical reports are presented in Enclosure B DeEta Delivers Solutions