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Ms. Margaret Lagorio <br /> San Joaquin County <br /> July 24, 1995 <br /> Page 6 <br /> explosive limit (LEL) meter and methane detector. If methane is found to be present, <br /> the depth of the pipe will be investigated. If it is indeed a sewer cleanout, the drill <br /> hole will be patched and no further investigation will be conducted. <br /> If the atmosphere within the casing is explosive and the depth suggests that it is a <br /> well, gases will be flushed from the casing, the atmosphere re-tested, and the cap <br /> removed when conditions are safe. If the atmosphere within the pipe is non-explosive <br /> or the depth suggests the presence of a well, the cap will be removed. A video log <br /> of the well will be taken. If obstructions are present, efforts will be made to remove <br /> them and video the casing to total depth. If the casing is intact and not permanently <br /> obstructed, the well will be purged and a groundwater sample collected. The water <br /> samples will be analyzed for TPH with characterization of peaks, VOCs and 17-Title <br /> 22 metals. The steel cap will be re-welded on the top of the casing after the water <br /> sample has been collected. <br /> Broken Asohalt <br /> Some areas at the project site are covered with asphalt which has deteriorated and <br /> broken. These are generally in areas where surface runoff can pond and infiltrate <br /> through the cracks. Compounds carried in surface runoff could impact soil in these <br /> areas. <br /> Soil gas and soil samples will be collected from two areas of broken asphalt; one <br /> location is in front of the boiler on the south side of the assembly shop and the other <br /> is near the northeast corner of the fab shop, near the reported dry well. <br /> At the boiler area, a rectangular section of asphalt has been replaced and the new <br /> paving has subsided and broken. A line of broken paving extends from the patched <br /> area to the east, parallel to the building. One soil gas sample will be collected from <br /> the rectangular area and one from approximately midway along the linear section, one <br /> soil gas sample will also be collected from the center of the broken area in front of the <br /> fab shop. Soil gas samples will be field screened with a PID. Soil samples will be <br /> collected from locations adjacent to the soil gas samples. Soil samples will be <br /> analyzed for TPH with characterization of peaks. <br /> Active On-Site Wells <br /> Two active on-site wells contain submersible pumps and are used for domestic and <br /> process water. These two will be sampled while the pumps are operating at the <br /> discharge point closest to each well. The groundwater samples will be analyzed for <br /> VOCs. In addition, DWR records will be checked to determine well depth and <br /> construction. <br /> rEH 1 DRO-SERRCR i G A Tetra Tech Company <br />