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1 I. INTRODUCTION Former Exxon Retail Site (RS) 7-3942 is a vacant site located at 4444 North Pershing Avenue, Stockton, California, on the southeast corner of the intersection of North Pershing Avenue and Rosemarie Lane Three grades of gasoline and used oil were stored in four underground storage tanks, which were removed in July 1986 A Shell service station and a 7-11 food and gasoline service store are located on the southwest and northwest corners, respectively, of the intersection of North Pershing Avenue and Rosemarie Lane Previous laboratory analyses have consistently identified TPH-g and BTEX in groundwater samples collected from MW8 and MW9, which are located adjacent to the Shell site and the 7-11 site, upgradient and cross-gradient of former Exxon RS 7-3942 On 24 August 1995, groundwater from 10 monitoring wells (MW1—MW5, MW8—MW 10, MW 12, and MW 13), 4 recovery wells (RW 1, RW2, RW3, and RW4), 2 piezometers (P1 and P2), 1 soil vapor extraction well (V3), and 1 infection well (IW 1) was purged and sampled Monitoring well MW6 was not sampled on 24 August, as there was insufficient water to make well purging possible Figure 1 shows the locations of all wells on and off the site, except MW 11, and the locations of former site facilities Figure 2 shows the vicinity of former Exxon RS 7-3942 and the locations of all offsite wells 2. SUMMARY OF RESULTS On 24 August, wells were monitored for the presence of liquid-phase hydrocarbons, using an ' optical interface probe The depth to water in the wells ranged from 22 80 feet to 29 58 feet below ground surface The approximate groundwater flow direction on 24 August was to the north-northeast, with a gradient of approximately 0 008 (Figure 3), which is consistent with previous groundwater monitoring data for the site Groundwater elevations have decreased approximately 1 2 feet since the previous quarter Groundwater elevation data for 24 August are presented in boldface type in Table 1, along with previous data Field documents are included as Appendix A After the depths to water were measured, all wells (MW 1—MW5, MW8—MW 10, MW 12, MW 13, RW 1--RW4, Pl, P2, IW1, and V3) were purged by a vacuum truck and sampled At least three well casing volumes of purge water were removed from each well before purging was ' terminated After purging, groundwater samples were collected with factory-cleaned disposable polyethylene bailers Groundwater samples were collected in 40-m1 VOA vials The vials were labeled and stored in an ice-filled cooler and transported under chain of custody Groundwater samples, a field-prepared rinse blank, and a Iaboratory-prepared trip blank were submitted to Sequoia Analytical, where they were analyzed for Total Petroleum Hydrocarbons as gasoline (TPH-g) by DHS-modified EPA Method 8015 and for benzene, toluene, ethylbenzene, and ' xylenes (BTEX) by EPA Method 8020 ' W P61 73942QS95 3 1