SITE INFORMATION AND CORRESPONDENCE

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CHRONOLOGY FORMER CHEVRON STATION_ 9-6258 2409 E MAIN STREET STOCKTON CA 94583 05/15/95 San Joaquin County Environmental Health Department(EHD) received Preliminary Subsurface Investigation report dated April 28, 1995 prepared by The Mark Group, Inc. The fuel station at the site had been abandoned since January 31,1976,but the exact date of the removal of the former fuel underground storage tanks (UST)is unknown. 6 exploratory borings were advanced in the vicinity of the former hydraulic lift and the suspected USTs at the site in March 1995. 170 milligrams per kilogram(mg/kg) of Total Petroleum Hydrocarbons as gasoline (I PH-g)and 0.051 mg/kg of benzene were reported in the soil sample collected from boring B2 at 3 feet below surface grade (bsg). 10/02/95 Prop-65 #95-119 and Unauthorized Release Report 95-U29 were issued. 10/11/95 A"Notice of Reimbursement"letter was sent to the responsible parry,and the site was entered into EHD Local Oversight Program (LOP) for investigation and clean up of the contamination. 06/18/96 Nor Cal Geophysical Consultants,Inc. conducted a geophysical survey at the site and { identified the existence of a waste oil tank and associated sump drained lines. 09/23/96 One 550 gallon waste oil tank was removed and transported off site by Erickson. Visible contamination and a split seam at the bottom of the fill end of the tank was noted. Soil samples from below tank and pipes were taken. 4,000 mg/kg of TPH-g were found in soil sample T-1 at 15 feet bsg. 380 cubic yards of impacted soil and approximately 200 yards of debris were disposed to offsite facilities. 05/23/97 Soil boring B-7 was drilled to 65 feet bsg in the southeast portion of the former UST I pit near samples T-1 and T-8. 1,700 mg/kg of TPH-g was detected at 26 feet bsg, but was non-detect at 56 feet bsg. Groundwater was encountered at approximately 58 feet bsg. 32,000 micrograms per liter (ug/1) of TPH-g was detected in the grab water sample. 04/06/99 . Monitoring well MW-1 to MW-3 were installed at the site. Results of the all soil 1 samples at depths of 10,25,and 45 feet bsg were non-detect in TPH-g,aromatic ` hydrocarbons,and methyl tert-butyl ether(MTBE). 05/28/03 MW-4 was installed at the site. Results of all soil samples from 30,50,and 65 feet -g,aromatic hydrocarbons,and all 5 oxygenates bsg were non-detect in TPH : 07/07/03 EHD received a 2,000-foot sensitive receptor survey. 1. 07/30/04 EHD received Second Quarter 2004 Groundwater Monitoring Report. 14 quarters i. of sampling have been conducted since installation of MW-1 thru MW-3,and 3 quarters for MW-4. With the exception of sporadic and minor concentrations of t aromatic hydrocarbons such as ethyl-benzene and xylenes,all higher boiling.poin ere non-detect in TPH-g,aromatic hydrocarbons, groundwater sampling results w and all 5 oxygenates. j 09/15/04 RWQCB agreed the site is a potential candidate for site closure status.