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i <br /> SOIL EXCAVATION AND REMEDIATION WORKPLAN <br /> Mid Cal Leasing <br /> SITE DESCRIPTION <br /> The site is located in a flat commercial/residential area in <br /> N central Stockton (Figure 1 - Location Map, 7.5 Minute Stockton West <br /> Quadrangle, USGS Topographic Map Series, 1976) . The facility <br /> consists of a large empty garage and adjoining storage rooms and <br /> exterior fenced storage areas. './ter 1) 4 ' OF- <br /> , <br /> The site is underlain by unconsolidyc'ed Quaternary alluvial <br /> sediment. Groundwater is estimated at 6Y ft below surface grade <br /> (San Joaquin County Flood Control and Water Conservation District, <br /> Map showing lines of equal depth to water wells, Fall, 1989) . <br /> PREVIOUS WORK <br /> An underground waste oil tank inside the garage was removed by <br /> Thorpe Oil in January, 1989. Soil samples were collected at 25 ft <br /> and 37 ft below gra.le and analyzed by Canonie Environmental for <br /> total extractable petroleum hydrocarbons and BTE&X. An unauthorized <br /> release of hydrocarbons was detected, ranging from 5300 mg/kg (ppm) <br /> TPH at 25 ft down to 140 mg/kg (ppm) at 37 ft. BTE&X compounds were <br /> ND at 0.025 resolution. <br /> The tank cavity is approximately 6 ft long x 4 ft wide x 4 ft <br /> deep. Approximately 3.5 cu. yds. of contaminated soil were removed <br /> during the excavation. Following excavation, this soil was <br /> reemplaced in the tank cavity. <br /> PROPOSED EXCAVATION AND SAMPLING <br /> We propose to mitigate the contamination at the site through <br /> excavation - and subsequent treatment on-site by means of <br /> biodegradation. The remediation will be undertaken in the following <br /> steps: <br /> 1) Prepare a site health and safety plan in accordance with <br /> occupational Safety and Health Guidance Manual for Hazardous <br /> Waste Site Activities - Prepared by National Institute for <br /> Occupational Safety and Health, Occupational Safety and Health <br /> Administration, U.S. Coast Guard and US Environmental <br /> Protection Agency, October 1985. <br /> 2) Notify the San Joaquin County - Environmental Health Division <br /> (SJEHD) 48 hours prior to work initiation. <br /> 3) Overexcavate the tank cavity to the following approximate <br /> dimensions: 10 ft long x 8 ft wide x 9 ft deep (2 ft beyond <br /> the existing excavation and 5 ft below present depth. ) <br /> 2 <br />