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Ank KLEINFELDER SOIL ASSESSMENT WORK PLAN FRENCH CAMP HOSPITAL SAN JOAQUIN COUNTY, CALIFORNIA 24-220152-A00 October 4, 1991 This work plan describes Kleinfelder's proposed investigation procedure to assess for soil contamination beneath three underground storage tanks at the San Joaquin County Hospital at 150 Hospital Lane in French Camp, California The underground tanks are located at two sites as shown on Plates 1 and 2 BACKGROUND Although the approximate locations of the tanks at each site are known from the fill and sounding ports, the actual tank configurations and dimensions are not known. Site #1 reportedly has a 5,000 to 6,000 gallon underground unleaded gasoline storage tank (attached map, T1) Although there is no written record of the tank installation date, it is believed that T1 may have been installed in the 1940's Because T1 recently failed a Precision Tank Test, San Joaquin County is considerin& removing the tank However, prior to finalizing removal plans, the county would like additional information about the extent (if any) of petroleum hydrocarbon impact to the soil beneath the site • Site #2 has two underground storage tanks (72, 70) of unknown size The tanks reportedly contained gasoline at one time, but have not been filled in at least 25 years Site #2 was believed to be the site of a single UST of unknown size; however, during a geophysical survey, two tanks were reported at the site (attached maps T2 and T3) A recent sounding of one of the tank's contents indicated that the tank was empty, but the sounding stick smelled of gasoline when retrieved T2 and T3 are scheduled for removal/abandonment to allow for the construction of a budding on the site Because actual locations of tanks, fuel lines and utility lines were not known, a geophysical survey was performed to locate these structures. Based on the findings of the geophysical survey, approximate boring locations were assigned as shown on Plates 1 and 2 Additionally, as soil contamination is often associated with the pump islands and these tank systems are reported to be approximately 50 years old, a shallow boring has been proposed beneath each pump island. Furthermore, as one of the tanks failed a tank test, if no soil contamination is detected in the proposed borings in the vicinity of that tank, San Joaquin County may want to consider additional borings nrar the fuel supply lines. The intended purpose of the assessment is to assess closure options of the tank sites The chemical analyses proposed are those normally required -- achieve regulatory approval for site closure Currently, two samples per boring are proposed to allow for assessment of contaminant concentrations if it exists, and, to a limited degree, vertical extent of the contamination FR25-91-23 Page 1 of 3 Copyright 1991 Kleinfelder, Inc