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Harding Lawson Associates <br /> U5.0 FIELD INVESTIGATION <br /> -, 5.1 Sol] Excavglign <br /> Excavation of soils containing elevated concentrations of petroleum hydrocarbons <br /> fwas conducted in the vicinity of the former dispenser under HLA supervision on June 6, <br /> 4 <br /> 1991. <br /> L Before starting the excavation, HLA obtained-a permit from the SJCDEH and <br /> _ contacted pertinent public and private entities to locate underground utilities in the <br /> vicinity of the site. The excavation was directed by an HLA field geologist under the <br /> supervision of a California registered geologist, using a backhoe operated by M.J. <br /> Aronson Excavating Inc., Sacramento, California. <br /> �+ Soil excavation began at the former dispenser location and expanded laterally and <br /> vertically. Each bucket of excavated soil was screened in the field for evidence of <br /> t <br /> petroleum hydrocarbons using an organic vapor analyzer (OVA) and by observing <br /> n discoloration and/or petroleum hydrocarbon odors. OVA measurements were collected <br /> by scraping off several inches of soil from each bucket before monitoring the vapors. <br /> The excavation was expanded until the soil showed no evidence of petroleum <br /> hydrocarbons. Excavated soils were separated into three stockpiles (stockpiles 1, 2, and <br /> 3) and placed on visqueen. <br /> To the north of the former dispenser location, the limit of excavation extended <br /> approximately 9 feet, with a width of between approximately 6 feet near the dispenser, <br /> and approximately 8 feet at its northern limit (Plate 3). The floor of the final <br /> excavation was approximately 5 feet deep from the former dispenser location, to the <br /> ' north for approximately'6 feet. From approximately 6 to 9 feet north of the former <br /> 4 dispenser location, the excavation floor was approximately 3 feet deep. <br /> L <br /> T19461-H 9 of 20 <br /> L <br />