SITE INFORMATION AND CORRESPONDENCE

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Y ` I f ENVIRONMENTAL HEALTH DEPARTMENT SAN JOAQUIN COUNTY Unit Supervisors Donna K.Heran,R.E.H.S. Carl Boins,R.an, .HS., S. Director 304 East Weber Avenue, Third Floor Mike Huggins,R.E.H.S.,R.D.T. Al Olsen,R.E.H.S. Stockton, California 95202-2708 Douglas W.Wilson,R.E.H.S. P 9} 468-3420 Margaret Lagorio,R.E.H.S. Program Manager Telephone: (20 c4ii FORr'\ RE.i3.S. Robert McClellon,R.E.H.S. Laurie A.Cotulla, Program Manager Fax: (209) 464-0138 JAN 211a"2601 ellos,R.E.H.S. TRUST OF MARY GARDELLA ESTATE OF JOE GARDELLA WINIFRED ALEXANDER DENNIS CASPE ESQ 525 2ND ST 2035 N PACIFIC AVE SANTA CRUZ CA 95060 SANTA CRUZ CA 95060 RE: STEFANOS GASOLINE 1419 E CHARTER WAY STOCKTON, CA 95205 San Joaquin County Environmental Health Department (EHD) has reviewed Groundwater Monitoring Report dated August 22,2002,prepared by Ramage Environmental (Ramage) for Wright Environmental Services, Inc. (Wright). Four quarters of sampling have been conducted since the installation of the four off-site monitoring wells MW-4, MW-5,MW-6, and MW-7. Analytical results of the groundwater samples from these new wells over the last four quarters were all non-detect at or above detection limits for Total Petroleum Hydrocarbons as gasoline (TPH-g),Benzene,Toluene, Ethyl-benzene,amylenes, methyl tertiary-butyl ether (MTBE), oxygenates, and 1,2-dicholoroethane (1,2-DCA). Groundwater samples from the on-site well 1v1W-2 continued to contain elevated concentrations of hydrocarbon compounds and gasoline additives: 180,000 micrograms per liter (µg/1) TPH- g, 4,100 µg/l benzene, and 260 µg/l 1,2-DCA for May 2002. 1,2-DCA was also present in the MW-3 sample at 290 µg/1. Tertiary butyl alcohol (TBA) has also been consistently reported in MW-3 sample results over the last 11 quarters,with concentrations as high as 100 µg/l. Free product in MW-2 was measured to be 0.02 feet thick in July 2002 and the well was not sampled for that reason. Depth to groundwater was measured at approximately 40 feet and 42 feet below surface grade (bsg) in July 2002, and the groundwater flow direction was consistently calculated to be between the east and east-southeast. A cross section (Figure 4) based on previously obtained cone penetrometer testing (CPT) data was provided in Groundwater Monitoring Report dated April 8, 2002 prepared by Ramage. The cross section indicated the presence of a sand zone beneath the current groundwater table at approximately 60 feet bsg, and another sand zone at approximately 105'bsg. Grab groundwater samples taken from both CPT-1 and CPT-2 at 60' feet bsg and 115 feet were impacted with petroleum hydrocarbon contamination and 1,2-DCA.