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lie I INTRODUCTION ' former Exxon Retail Site (RS) 7-3708 is an active U S A Petroleum station located at 2705 Country Club Boulevard in Stockton, California, at the northwest corner of the intersection of Ryde Avenue and Country Club Boulevard Elevation of the ground surface at the site is approximately 1 to 2 feet ' abo,,c mean sea level The site slopes down toward the northeast and southwest corners 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 10 May 2001, wells MW1, MW4-MW10, VEW1, and VEW3 were gauged Groundwater ' samples were collected from these wells and the samples were analyzed for Total Petroleum Hydrocarbons as gasoline (TPH-g), for benzene, toluene, ethylbenzene, and total xylenes (BTEX), ' and for methyl t-butyl ether (MTBE) The current depth-to-water measurements and calculated groundwater elevations are presented in ' boldface type in Table 1, along with previous data Current groundwater elevations are also shown in Figure I The groundwater flow direction on 10 May was to the east-southeast, with a gradient of approximately 0 0002 Liquid-phase hydrocarbons were not observed in any of the wells ' After the depths to water were measured, the wells were purged Field parameters ofH temperature and electrical conductance of the purged water were measured for approximately every ' well casing volume removed during purging Copies of the field documents are included as Appendix -� 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 Wells that dewatered were allowed to recharge prior to sampling The samples were poured into 40-m1 glass VOA vials 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 by Cal EPA-modified EPA :Method 8015, for BTEX by EPA Method 8021B, and for MTBE by EPA Method 8260B The results are presented in boldface type, along with previous analytical data, in Table I, and are shown in Figure I 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 August 2001 Groundwater samples will be analyzed p y for TPH-g, BTEX, and MTBE I 4 P1 IL IS'I iti�I ntu LP tj ail l 1