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A letter from the San Joaquin County Environmental Health Department (EHD), dated 07 March ,. 1996, indicated that further investigation related to the former UST would be required before site closure could be issued. SITE ASSESSMENT ACTIVITIES A total of eight soil probe borings(P 1 through P8)were advanced at the site,under the observation of a representative of the EHD. On 19 September 1995,probe boring P1 was advanced north of the former UST area;probe boring P2 was advanced near the center of the former UST excavation;and probe boring P3 was advanced near the former dispenser location. Each of these boring were advanced to a depth of 25 feet bsg. On 21 April 1997, P4 was advanced in the City of Stockton right-of-way in Fremont Street. Four additional soil probe borings(P5 through P8) were advanced on the site, in the vicinity the former UST, including probe boring P7,which was advanced under the building on the site. Each of these probing were advanced to a vertical depth of 15 feet bsg. • TPH-g was detected in soil samples from probe boring P2, P3 and P7 at concentrations as high as 230 ppm(P3-10').BTE&X compounds were detected in soil samples collected from P3 at concentrations ranging from 0.010(ethyl benzene,P3-25')to 19 ppm(xylenes,P3-10'). Petroleum hydrocarbons were not detected in soil samples analyzed from any other probe borings advanced during this investigation. • Analytical results of soil samples submitted for physicochemical analysis and microbiological enumeration indicate that there is microbial activity at the site, however segregated from the area of the hydrocarbon release.The lack ofbiodegrading bacteria in the area of the dispenser may be due to the presence of biotoxic compounds in the subsurface at the site, such as metals or pesticides. However, adequate concentrations of necessary nutrients for microbe growth and sustenance were present in the soil at the site. • TPH-g was detected in four of six grab ground water samples collected from the site at concentrations ranging from 510 to 94,000 parts perbillion(ppb,reported as micrograms per liter). BTE&X compounds were detected in five of six samples analyzed at concentrations ranging from 1.3 ppb benzene in boring P1 to 19,000 ppb of toluene in boring P6. MTBE was detected at concentrations up to 290 ppb. No petroleum hydrocarbons were detected in the grab water sample collected from the City of Stockton right-of-way in Fremont Street, located in the apparent up-gradient direction from the former UST area. On 15 and 16 June 1999, AGE advanced four soil boring for the construction of ground water monitoring wells, collected soil samples and procured laboratory analysis of the soil samples. The four soil borings (MW-1 through MW-4) were advanced utilizing hollow-stem auger drilling techniques and were subsequently completed as monitoring wells. Advanced GeoEnvironmental,Inc.