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' A letter from the San Joaquin County Environmental Health Department (EHD), dated 07 March <br /> 1996, Indicated that further investigation related to the former UST would be required before site <br /> ' closure could be Issued <br />' SITE ASSESSMENT ACTIVITIES <br /> A total of eight soil probe borings(P 1 through P8)were advanced at the site, under the observation <br />' of a representative of the EHD On 19 September 1995,probe boring P 1 was advanced north of the <br /> former UST area,probe boring P2 was advanced near the center of the former UST excavation,and <br /> probe boring P3 was advanced near the former dispenser location Each of these boring were <br /> advanced to a depth of 25 feet bsg <br />' On 21 April 1997, P4 was advanced in the City of Stockton right-of-way in Fremont Street Four <br /> additional soil probe borings(P5 through P8)were advanced on the site, in the vicinity the former <br /> UST, including probe boring P7, which was advanced under the building on the site Each of these <br /> probing were advanced to a vertical depth of 15 feet bsg <br /> TPH-g was detected in soil samples from probe boring P2, P3 and P7 at concentrations as <br /> high as 230 ppm(P3-10') BTE&X compounds were detected in soil samples collected from <br /> P3 at concentrations ranging from 0 010(ethyl benzene,P3-25')to 19 ppm(xylenes,P3-10') <br /> Petroleum hydrocarbons were not detected in soil samples analyzed from any other probe <br /> borings advanced during this investigation <br />' Analytical results of soil samples submitted for physicochemical analysis and <br /> microbiological enumeration indicate that there is microbial activity at the sne, however <br /> segregated from the area of the hydrocarbon release The lack of biodegrading bacteria in the <br />' area of the dispenser may be due to the presence of biotoxic compounds in the subsurface <br /> at the site, such as metals or pesticides However, adequate concentrations of necessary <br /> nutrients for microbe growth and sustenance were present in the soil at the site <br />' <br /> TPH-g was detected in four of six grab ground water samples s collected from the site at <br />' concentrations ranging from 510 to 94,000 parts perbillion(ppb,reported as micrograms per <br /> liter) BTE&X compounds were detected in five of six samples analyzed at concentrations <br /> ranging from 13 ppb benzene in boring P1 to 19,000 ppb of toluene in boring P6 MTBE <br /> t was detected at concentrations up to 290 ppb No petroleum hydrocarbons were detected in <br /> the grab water sample collected from the City of Stockton right-of-way in Fremont Street, <br /> located in the apparent up-gradient direction from the former UST area <br />' On 15 and 16 June 1999, AGE advanced four soil bona for the construction of ground water <br /> g <br /> monitoring wells, collected soil samples and procured laboratory analysis of the soil samples The <br />' four soil bonngs (MW-1 through MW-4) were advanced utilizing hollow-stem auger drilling <br /> techniques and were subsequently completed as monitoring wells <br />' Advanced GeoEnvironmental,inc <br />