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IIINICI � IIRNIR Sac am nto,l CA 95864 <br /> n; <br /> ENGINEERING AND ENVIRONMENTAL SERVICES Telephone: (916) 485-7222 <br /> FAX: (916) 485-8098 <br /> 23 September 1997 <br /> Mr. Charles Leubner <br /> Stockton Unified School District <br /> 1932 N. El Pinal Drive <br /> Stockton, California 95205 <br /> Subject: Results of Preliminary Site Assessment for Stagg High School <br /> HLT 00814 <br /> Dear Mr. Leubner: <br /> This letter presents results of the soil investigation conducted at Stagg High School on the 14' <br /> and 15`h of August, 1997. The investigation was conducted in accordance with the Preliminary <br /> Site Assessment Proposed Work Plan (9 July 1997), including comments presented by San <br /> Joaquin County Public Health Services in their letter of 22 July 1997. The investigation <br />� . consisted of collection and analysis of soil and groundwater samples from three areas where <br /> gasoline and diesel hydrocarbons were detected during the removal of two underground storage <br /> tanks (Refer to Figure 1) in December, 1990. <br /> SAMPLING RATIONALE <br /> Gasoline Tank <br /> During the removal of the 500-gallon gasoline storage tank, one soil sample was collected from <br /> the tank excavation at the location shown on Figure 2. Total petroleum hydrocarbons as gasoline <br /> (TPH-G) was detected at a concentration of 290 mg/Kg and benzene, toluene, ethylbenzene, and <br /> xylenes were detected at concentrations of 75 ug/Kg, 2,500 ug/Kg, 1,900 ug/Kg, and 20,000 <br /> ug/Kg, respectively. Ethylene dibromide was detected at 4.1 ug/Kg. <br /> Four soil borings were sampled using the GeoProbe method to evaluate the vertical and lateral <br /> extent of petroleum hydrocarbons remaining in the soil (see Figure 2). All four soil borings were <br /> driven to a depth of 25 feet below the ground surface, which was 12 feet below the groundwater <br /> surface noted from the GeoProbe sampling. In accordance with the County's request, one <br /> sample was also collected of groundwater for laboratory analysis. The hydrocarbons of concern <br /> at this site were total petroleum hydrocarbons as gasoline, benzene, toluene, ethylbenzene, <br /> . xylenes, MTBE and ethylene dibromide (EDB). <br /> f i <br /> 1 <br />