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Wright <br /> Environmental <br /> Services, Inc. <br /> September 28, 1995 <br /> Project No. 4062-R <br /> Linden Unified School District <br /> 18351 East Main Street ` <br /> Linden, CA 95236 IS <br /> Attn: Mr. Chuck Altree <br /> R e: Subsurface Soil and Groundwater Sampling <br /> Groundwater and Vadose Well Installation and Modification <br /> at the Waterloo School, 7007 N. Pezzi Road, Stockton, CA <br /> Dear Chuck, <br /> Wright Environmental Services, Inc. (Wright) is pleased to provide this report of <br /> activities for the Linden Unified School District (District) at the above referenced <br /> location. As you know Wright has discussed this project in several conversations <br /> with the San Joaquin County Public Health Services-Environmental Health Division <br /> (PHS-EHD) representative, Linda Turkatte and PHS-EHD's desire to implement interim <br /> site remediation at the Waterloo School (site), see Figure 1. <br /> Background and Technical Approach <br /> Initial work done by Waterwork and Resna has provided a limited assessment of the <br /> contamination arising from the former gasoline underground storage tank (UST) <br /> which was next to the maintenance building on the site. Soil contamination in the <br /> vadose zone has been only partially defined, with data gaps at the depth interval of <br /> about 26.5 feet to 56 feet, and below 82 feet. The highest concentrations of Total <br /> Petroleum Hydrocarbons as Gasoline (TPHG) observed were 7,500 parts per million <br /> (ppm) and Benzene at 35 ppm at the 26.5 foot depth. <br /> Wright's workplan included additional soil sampling and chemical analysis to <br /> further define the vadose zone soil and to install one groundwater monitoring well <br /> and one shallow vapor extraction well. An existing vapor extraction well was to be <br /> modified for possible use in the shallow soil zone (upper 30 feet) for anticipated soil <br /> vapor extraction. <br /> Field Work-Exploratory Borings and Well Construction <br /> Two exploratory borings were drilled at the locations shown on Figure 2. Drilling <br /> and well installation permits were secured prior to doing the field work. One <br /> borehole was converted to a groundwater monitoring well and one was converted to a <br /> shallow vapor extraction well. The boreholes were drilled with truck mounted <br /> hollowstem auger drilling equipment by Spectrum Exploration of Stockton, CA. All <br /> drilling equipment and sampling tools were cleaned prior to arriving and before <br /> leaving the site. The augers were advanced to the desired soil sampling depth <br /> interval and a drive split spoon sampler was driven ahead of the drill bit. The <br /> Linden School District <br /> 4220 Commercial Dr. #5 - Tracy, California 95376 i0% <br /> Telephone (209) 833-0758 - Fax (209) 832-5152 <br />