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Wm. J. Hunter & Associates 2220 Loma Vista Dr. Registered Geologists Sacramento, CA 95825 Petroleum&Mineral Appraisers (916)972-7941 FAX(916)972-1683 November 12, 1996 Margaret Lagorio, REHS, Supervisor San Joaquin County Public Health Services Environmental Health Division P.O. Box 388 Stockton, CA 95201-0388 Ref: J. H. Simpson Co., 4025 Coronado Ave., Stockton Site Code- 1068 Dear Margaret; We have been retained by the above firm to assist in compliance with your correspondence of September 16, 1996 requiring a workplan to investigate the extent of contamination encountered at the above site during removal of a UST which had contained gasoline. We.have reviewed the data concerning that operation, and do not understand why your office is requesting further investigative work. Two soil samples were taken at 12' beneath the removed tank as required by the regulations. The results of the laboratory analyses of those samples showed that benzene was ND; toluene was present only in one sample at .0082 mg/kg; ethylbenzene was present in one sample at .005 mg/kg, xylene was present at .08 mg/kg in one sample, and MTBE was present at a maximum concentration of 1.0 mg/kg . Lead was ND. We have enclosed a copy of the laboratory analyses of that work for your information. Based upon San Joaquin County Flood Control District maps, the highest depth to water was in the Spring of 1983 at about -19' MSL. USGS topographic maps indicate that ground elevation is approximately 20' MSL; therefore depth to water would be 39' below ground level. The soil samples were taken at 12' bgl, which would be 27' above highest groundwater. Constructing the Leaching Potential Analysis for Gasoline & Diesel, (Table 2-1 from the LUFT Manual,) shows that the allowable levels for BTEX are .3/.3/1.0/1.0, far above those measured from the soil samples taken after tank removal operations. MTBE is not covered by that worksheet, but The State of California Drinking Water AL for MTBE is 35 ppb. Since the soil samples were taken some 27' above the highest groundwater levels, and some 50' above current levels, those standards are not applicable to this site. If site investigative work is being required because of the presence of MTBE, we request that your office furnish us with some written guidelines to assist in the preparation of the workplan. Our client is in the process of applying for reimbursement from the State Cleanup Fund, but does not intend to wait for acceptance before beginning the work. However, since the first $5,000 is not covered, and it may be some time before the claim is processed and funds reimbursed, we want to submit a workplan that will provide the information your office requires with a minimum expenditure of funds. 1