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1 INTRODUCTION Former Exxon Retail Site (RS) 7-3708 is an active U S A Petroleum station located at 2705 Country Club Boule,,ard in Stockton, California, at the northwest corner of the intersection of Ryde 111.venue and Country Club Boulevard Elevation of the ground surface at the site is approximately 1 to 2 feet ' above mean sea level The site slopes down toward the northeast and southwest comers from a slight topographic high across the center ' There are two underground storage tanks at the site containing diesel fuel and unleaded gasoline Groundwater monitoring has been conducted at the site since 1991 ' 2 GROUNDWATER MONITORING ' On 7 August 2000, wells MWl, MW4-MW10, VEW1, and VEW3 were gauged for depth to water and for liquid-phase hydrocarbons (LPH) with an optical interface probe Groundwater samples were collected from wells MWI, MW4-MW10, and VEW1, and the samples were analyzed for Total ' Petroleum Hydrocarbons as gasoline (TPH-g) and as diesel (TPH-d), for benzene, toluene ethylbenzene, and total xylenes (BTEX), and for methyl t-butyl ether (MTBE) Well VEW3 was functionally dry on 7 August and no groundwater Sample could be collected ' The current depth-to-water measurements and calculated groundwater elevations are presented in boldface type in Table 1, along with previous data, and current groundwater elevations are shown in Figure l The groundwater flow direction on 7 August was to the north-northeast, with a gradient of approximately 0 0007 LPH was not observed in any of the wells ' After the depths to water were measured the wells were purged Field parameters of pH, temperature, and electrical conductance of the purged water were measured for approximately every well casing volume during purging Field documents are included in Appendix A When the field ' parameters were stable (less than a 10 percent change from the previous reading for temperature and electrical conductance and not more than 0 1 pH units) and approximately 3 casing volumes were removed from each well, purging was stopped and samples were collected, using factory-cleaned ' disposable bailers The samples were poured into 40-m1 glass VOA vials and I-liter amber glass bottles and stored in an ice-filled cooler All samples were handled and transported under chain of custody ' The samples were submitted to SPL, Inc in Houston, Texas, and were analyzed for TPH-g and TPH- d by Cal EPA-modified EPA Method 8015 and for BTEX and MTBE by EPA Method 8021B The ' results are presented in boldface type, along with previous analytical data, in Table 1, and are shown in Figure 1 The laboratory analytical report and chain-of-custody documentation are included in Appendix B ' 3 WORK PROPOSED FOR NEXT QUARTER ' Groundwater will be gauged and sampled in No\,eiyiber 2000 Groundwater samples will be analyzed for TPH-g, BTEX and MTBE F hqt5�7e719 n l Q'00