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1. 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 Groundwater monitoring wells MW 1-MW7 were installed on the site and MW8--MW 10 were finstalled off the site between January 1987 and April 1988 RW 1-RW3 were installed on the site in May 1990 From January through April 1991, EA installed IW1, P1, P2, RW4, VI-V4, MW 11, MW 12, and two vapor monitoring cluster wells on and off the site Two air sparging wells (SWI, SW2) and one offsite monitoring well (MW13) were installed in May 1993 Soils beneath the site consist of clayey and silty alluvial sediments to a depth of 10--15 feet below ground surface Between 10-15 feet and 35-40 feet the soils consist of coarser ' sediments—clayey sands, sands, and gravels—that are interbedded with discontinuous clayey lenses ranging from a few feet to 25 feet in thickness The coarser sediments are underlain by clays and silts to an unknown depth A Shell service station and a 7-11 food and gasoline service store are located at the southwest and northwest corners, respectively, of the intersection of North Pershing Avenue and Rosemarie Lane Previous sampling has consistently found TPH-g and BTEX in MW8, which is located adjacent to the Shell site, upgradient of former Exxon RS 7-3942 On I November 1994, groundwater from six monitoring wells (MW1, MW8, MW9, MW10, MW 12, and MW 13), three groundwater recovery wells (RW 1, RW3, and RW4), two piezometers (P1 and P2), one soil vapor extraction well (V2), and one infection well (1W1) ' was purged and sampled Figure 1 shows the locations of all wells on and off the site, except MW11, and the locations of former site facilities Figure 2 shows the vicinity of former Exxon RS 7-3942 and locations of all wells off the site 2. SUMMARY OF RESULTS On 1 November, wells were monitored for the presence of liquid-phase hydrocarbons and water levels in all wells on and off the site (with the exception of wells MW7, NMI 1, SW1, ' and SW2) were measured with an optical interface probe The depth to water in all wells accessed ranged from 27 64 feet to 33 97 feet below ground surface The approximate groundwater flow direction on 1 November was to the north-northeast, with a gradient of ' 0 008 (Figure 3), consistent with previous groundwater monitoring data for the site Groundwater elevations have decreased approximately 0 35 feet since the previous quarter Groundwater elevation data for 1 November are presented in boldface type in Table 1, along with previous data Field documents are included as Appendix A 73942Q1194 2 1