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Avenue, Suite <br /> -- - - 1117 Lone P�desto, CA 953561 <br /> AWwww atc-enviro com <br /> J 209 579 2221 <br /> Fax 209 579 2225 <br /> ASSOCIATES IN C <br /> D c' <br /> J Lc:�LU <br /> FEB 0 5 2004 <br /> February 2, 2004 ENVIRONMENT HEALTH <br /> 54 14885 0001 PERPAIT/SERVICES <br /> Ms Margaret Lagono <br /> San Joaquin County <br /> Environmental Health Department <br /> 304 E Weber Street, Third Floor <br /> Stockton, Califorma 95202 <br /> Subject First Quarter 2004 Groundwater Monitoring Report for Three Palms Grocery, 6732 <br /> East Highway 88, Stockton, California, Site Code 1830 <br /> Dear Ms Lagono <br /> This letter report summarizes field activities conducted during the First Quarter 2004 by ATC <br /> Associates Inc at the subject site (Figure 1) Monitoring was performed to evaluate the <br /> groundwater flow direction and magnitude in the uppermost aquifer Sampling was performed to <br /> monitor the distribution of petroleum hydrocarbons in groundwater at the site <br /> • <br /> BACKGROUND <br /> The site is located on the south side of Highway 88 (Waterloo Road) and on the east side of <br /> Fairchild Lane, Stockton, California, as shown on Figure 1 The site is presently occupied by <br /> Three Palms Grocery (a convenience store), a beauty salon, and an adjacent residence A <br /> domestic well, which provides water to the site, is located north of the residence (Figure 2) <br /> Prior to July 1984, one 550-gallon waste oil UST, identified as Tank #4, was emptied of product, <br /> filled with sand, and capped with concrete In November 1986, one 1,000-gallon regular <br /> gasoline UST, identified as Tank #3, was removed and disposed of A soil sample collected <br /> during the removal of Tank #3 contained elevated concentrations of petroleum hydrocarbons In <br /> May 1989, one 1,000-gallon unleaded gasoline UST, identified as Tank #1 was filled with five <br /> cubic yards of concrete Currently, two other USTs remain in place and are in operation at the <br /> site These USTs are located approximately 40 feet east of the tanks which were closed in place <br /> On June 18, 1998, an ATC geologist supervised the advancement of two soil borings (SBI and <br /> S132) to 86 5 feet below ground surface (bgs) to assess current subsurface conditions at the site <br /> Petroleum hydrocarbon constituents were detected in soil samples collected from borings S131 <br /> and SB2 The highest reported constituent concentrations were observed in soil samples <br /> collected at 25 5 feet bgs in each of the borings The highest concentrations of petroleum <br /> constituents at this depth were observed in SBI and include total petroleum hydrocarbons as <br /> . gasoline (TPHg) (9,500 mg/kg), toluene (65 mg/kg), ethyl benzene (82 mg/kg), and xylenes (470 <br /> mg/kg) The petroleum hydrocarbons appear to attenuate rapidly with depth as indicated greatest <br /> w\1 4885\reportsUgtr2004 doc 1 <br /> ENVIRONMENTAL, GEOTECHNICAL AND MATERIALS PROFESSIONALS <br />