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Site Background Information: Former Ocampo Property <br />Page 2 of 6 <br />PREVIOUS SITE SUBSURFACE INVESTIGATIONS <br />November 1998: <br />A soil boring was advanced at the site on November 25, 1998 by Upgradient <br />Environmental Consultants; petroleum hydrocarbons were detected in soil samples <br />collected from the boring. Analytical results of the samples are included in Table 1. Due <br />to the detection of contamination, a work plan addendum was prepared by Upgradient <br />Environmental Consultants, and a revised addendum prepared by AGE for the site in 1999, <br />to advance four soil borings and install three ground water monitoring wells. The revised <br />addendum was approved by the San Joaquin County Environmental Health Department <br />(EHD) by correspondence dated 19 May 1999. <br />October 2002: <br />On 17 October 2002, three soil probe borings (B1 through B3) were advanced at the site <br />as part of site assessment activities. A total of three soil samples were submitted to <br />McCampbell Analytical, Inc (MAI), a State of California Department of Health Services <br />(DHS)-certified analytical laboratory, for analysis. Petroleum hydrocarbons and volatile <br />organic compounds were not detected in any of the samples analyzed. Laboratory results <br />of selected soil samples detected barium and chromium in soil samples collected from <br />borings B1, B2, and B3 at maximum concentrations of 120 milligrams per kilogram(mg/kg) <br />(B2-10) and 27 mg/kg (B1-10), respectively. Lead was detected in soil samples collected <br />from borings B1 and B2 at a maximum concentration of 6.7 mg/kg (B1-10). Arsenic was <br />detected in soil samples collected from borings B1 and B3 at a maximum concentration of <br />3.4 mg/kg (B3-10). <br />On 17 October 2002, soil boring B4 was advanced at the site and the data was held for <br />future reporting. On 17 and 18 February 2004, B5 and B6 were advanced for the collection <br />and analysis of soil and 'grab' groundwater samples. The probe borings B4, B5, and B6 <br />were advanced to depths of 47 feet, 54 feet, and 57 feet bsg, respectively. <br />TPH-g was detected in all soil samples collected from B5 and one sample from B4. <br />Concentrations ranged from 2.2 mg/kg in sample B4-35 to 16,000 mg/kg in sample B5-33. <br />The most significant concentrations of hydrocarbons in soil in boring B5, located at the <br />former UST area, were at depths greater than 30 feet bsg and concentrations are elevated <br />in samples to the total depth of the boring. TPH-d was detected in the samples collected <br />from B5, at concentrations ranging from 640 mg/kg to 11,000 mg/kg. However, the MAI <br />laboratory report notes the diesel concentrations are typical of aged or 'weathered' <br />gasoline patterns. One or more BTEX compounds were detected in the following soil <br />samples, B4-35, B6-45, B6-55, and all samples from B5, at the following maximum <br />concentrations: 50 mg/kg benzene (B5-33), 1,800 mg/kg toluene (B5-18), 2,100 mg/kg <br />ethylbenzene (B5-18) and 3,690 mg/kg total xylenes (B5-18). 1,2-DCA was detected in the <br />,4dvanced GeoEnvironmental, Inc.