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P <br /> LETTER REPORT—WASTE OIL TANK SITE ASSESSMENT <br /> POSDEF Power Company, 2526 West Washington Street, Stockton <br /> October 29, 1998 <br /> Page three <br /> A California Registered Geologist logged both boreholes using the Unified Soil <br /> Classification System. Soil boring logs are attached. Following sampling, both <br /> boreholes were abandoned with neat cement grout. The surface pavement was <br /> restored using ready-mix cement. <br /> ' Results of the Investigation <br /> Soils beneath the site consisted of tank fill and imported compaction materials. At SB-1, <br /> soils consisted of a loose, light brown, poorly-graded sand to a depth of approximately 4 <br /> feet bgs and pea gravel from 4 to 5 feet bgs. At SB-2, soils encountered consisted of a <br /> ' highly-compacted sandy gravel to a depth of approximately 4 feet bgs and pea gravel <br /> from 4 to 5 feet bgs. Groundwater was not encountered in either boring. at the total <br /> drilling depth of 5 feet bgs. <br /> The laboratory results from the soil sample analyses indicated 43 mg/kg of motor oil, <br /> small amount of Chromium, Nickel and Zinc, that were over the detection limit. All other <br /> analyses were non detect. The laboratory report is attached. <br /> Conclusions and Recommendations <br /> The results of this site assessment indicate that the soil in close proximity to the bottom <br /> of the waste oil tank, Record ID#: TA253501, exhibit contaminants of TPH- as motor oil, <br /> chromium, nickel, and zinc, all of which are below the action levels for those <br /> contaminants. <br /> Based on the results of the site assessment and given the structural and logistical <br /> concerns associated with removing the tank, Wright recommends that the PHS/EHD <br /> permit POSDEF to close-in-place the subject tank. <br /> Thank you for your assistance on this project. If you have questions or need any <br /> additional information, please call our Tracy office at (209) 833-0758. <br /> Sincerely, <br /> Wright Environmental Services, Inc. Attachments: Figure 1, <br /> Location Map and <br /> Picture <br /> PHS/EHD Drilling <br /> Joe Ramage, R.G. ��,11E� GEp� Permit <br /> Project Geologist Soil Boring Logs <br /> Laboratory Report <br /> Debra Anderson Exp, ; 00 <br /> o <br /> Operations Manager <br /> 'TF OF CAl\FOQ�\! <br />