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1 <br /> Nflxicl_ _IHNII <br /> Mr. Charles Leubner <br /> 6 December 1990 <br />' Page 3 <br /> each of the excavations One sample was collected at each corner of the excavation, <br /> immediately adjacent to the edge of the concrete slab. Each of these samples was <br /> collected at a depth of approximately two feet into the native soils beneath the level of <br /> the bottom of the tank One sample from each excavation was also collected from a hole <br /> 1r that, was punched in the center of the concrete slab using a jackhammer mounted on the <br /> backhoe arm. This sample was collected at a depth of one to two feet into the native soil <br /> beneath the bottom of the concrete slab Table 1 summarizes the locations of the samples <br />' coIlected for laboratory analysis <br /> The two samples collected from the center of the excavations were collected by attaching <br />' a core sampler to lengths of auger extension rods. The core sampler was then lowered into <br /> the hole that had been punched in the bottom of the concrete slab and driven into the <br /> native soil with a slide-hammer attached to the opposite end of the extension rods Once <br />' the core sampler was removed from the excavation the brass liner containing the sample <br /> was removed from the sampler and prepared for transport to the laboratory using the <br /> protocol outlined above Soil samples from beneath the piping were collected in a similar <br />' manner. <br /> LABORATORY ANALYSIS <br /> The analytical program for the soil samples collected from the 10,000 and 6,600 gallon <br /> diesel tank excavation consisted of the following analyses, as specified by San Joaquin <br /> County in their permit to remove the underground tanks• <br />' Anal, sis Method <br /> Total Extractable Petroleum Hydrocarbons GC-FID with soxhlet sample <br /> preparation <br /> Benzene, Toluene, Ethylbenzene and EPA Method 8020 <br /> Xylene <br /> At the same time that a sample was collected for laboratory analysis, a sample was <br />' collected from the backhoe bucket to monitor for the presence of organic vapors. The <br /> results of laboratory analyses and field monitoring for the presence of organic vapors is <br /> shown in Table 1. <br />' EVALUATION OF SOIL SAMPLING RESULTS <br /> A leaching potential analysis was performed for each of the tanks on the site, based on the <br /> method outlined in the October 1989 version of the Leaking Underground Fuel Tank (LUFT) <br /> Field Manual. The leaching potential analysis for the 10,000 gallon diesel tank is shown in <br />