SITE INFORMATION AND CORRESPONDENCE_FILE 2

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r Site Background Information CHAPIN BROTHERS INVESTMENTS,INC. 1766 Monte Diablo Avenue, Stockton, California The site is located at the southeast intersection of Monte Diablo Avenue and Buena Vista Avenue. It is our understanding that the site was operated as a gasoline service station from the late 1930's to December 30, 1990.During the 1930's Shell Oil Company leased the property and installed three small underground storage tanks(USTs)were present on the property.Additional larger tanks were added to the site between 1941 and 1975. Shell reportedly replaced a leaking 8,000-gallon UST in 1963. Between 1941 and 1975 Chapin Brother Investments leased the site from Shell Oil Company;while between 1975 and 1985 CBI leased the site from Tom Blanchard and Shell as the master lease holder. CBI acquired the site in 1985. From 1991 to the present the site has operated as a automotive repair facility. The site is currently occupied by a single L-shaped building, which houses the auto repair business. The building is surrounded on the north and west by an asphalt-paved parking area. INITIAL SITE INVESTIGATION On 30 November 1990,one groundwater monitoring well(MW-1)was installed at the site between the eastern 8,000-gallon USTs. Three soil samples collected at 9 feet, 15 feet and 20 feet below surface grade(bsg) was analyzed. Total petroleum hydrocarbons (TPH as gasoline)were detected at 34 milligrams per kilogram(mg/kg),non detected at 15 feet bsg and detected at 15 mg/kg at 20 feet bsg. Maximum benzene, toluene, ethylbenzene and total xylene (BTEX) concentrations were 0.26 mg/kg, 0.57 mg/kg, 0.27 mg/kg and 1.0 mg/kg,respectively. However,a ground water sample from the well had detections of TPH-g at 200,000 micrograms per liter(µg/l) and BTEX at 31,000 µg/1, 11,000 µg/l, 1,900 µg/l and 5,200 µg/1 ,respectively. FREE-PRODUCT IN GROUND WATER In August 1993 free hydrocarbon product was detected in MW-1. The depth to product was measured at 21.64 feet below the top of the well casing and the depth to water was measured at 24.98 feet. Approximately, three feet of free-product was observed over the water table. The following weeks the depth to ground water measured at 21 feet below casing grade, without significant free product. Advanced GcoEncironmentrl,Inc.