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w,pg Weir-M- MON& e I t a 33 G Gat, :a Environmental '�`r Sacrar,errc.�,:95-570 consultants,Inc. FAX November 7, 1991 Mr. Glenn R. Dembroff Ultramar Inc. 525 West Third Street Hanford, California 93230 Subject: Quarterly Monitoring Report, Third Quarte; 1991 Beacon Station No. 695 900 South Cherokee Lane,Lodi, California Delta Project No. 40-91-831 Dear Mr. Dembroff: Delta Environmental Consultants, Inc. (Delta), has been authorized by Ultramar Inc. (Ultras=), to conduct a hydrogeologic investigation at Beacon Station No. 695 located at 900 Souf this irrvesjg th Chero ,^ San Joaquin County,Lodi,California(Figures I and 2). The the ground water levels and the distribution of petroleum hydrocarbon aeon kee Lane, constituents in the is to monitor beneath the sate. This letter report contains the results of theater ground water sampling performed at the site on September 20, I991. Field work conducted at the site by Delta was onitoring and performed in accordance with the field methods and procedures described in Enclosure A. A total of 23 ground water monitoring wells are present at the site. Monitoring wells MW-I8,MW-24, MW-27 and recovery well RW-I,contained measurable ground water on September 20, 1991 (Table 1). Ground water was not present in the remaining monitoring wells at the site. Ground water was present at the site between approximately 63 and 71 feet below the surface. Ground water elevation contours based on the September 20, 1991, data are illustrated in Figure.3. These contours indicate the ground water flow direction is toward the southeast (Figure 3), with an average hydraulic gradient n approximately 0.006-foot per foot. Ground water level data collected from each monitoring well n the of site since January 1988 is presented in Enclosure B. Ground water samples collected on September 20, 1991, were submitted to a California-certified laboratory for analysis of benzene, toluene, ethylbenzene, and xylenes 03TEX) and total m petroleu hydrocarbons(TPH)as gasoline. A summary of ground water sample analytical results i::,presented in Table 2, A dissolved benzene concentration map based on the September 1991 ground --iter sample analytical results is illustrated in Figure 4. A summary of ground water analytical results for samples collected at the site since-1985 is presented in Enclosure C. Copies.of the field sampling information - sheets are presented in Enclosure D. Copies of the September 1991 ground water sample laboratory reports are presented in Enclosure E. Deka Delivers Scuions