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Ms Lori Duncan Project No 880-039 IA <br /> June 18, 2003 <br /> Page 3 <br /> reported at approximately 10 feet below ground surface (bgs) near the former USTs <br /> Total Oil and Grease were reported in the soil sample collected near the former UST <br /> cavity (located near the building) at a concentration of 10,000 parts per million (ppm) <br /> Polychlorinated biphenyls, TPHd, or chlorinated hydrocarbons were not detected in soil <br /> samples analyzed from soil borings B-2R and B-6R Benzene, toluene, ethylbenzene, <br /> tand total xylenes (BTEX), TPHg, and methyl tert-butyl ether (MtBE) were reported in <br /> the groundwater sample collected from monitoring well MW-1R TPHg and benzene <br /> were reported at concentrations of 33,000 and 1,400 parts per billion (ppb), respectively <br /> MtBE was reported at a concentration of 550 ppb <br /> Quarterly groundwater monitoring has occurred since September 1996 The last <br /> quarterly monitoring event was performed on February 11, 2003 Data collected was <br /> within the site's historical range Groundwater elevations ranged between —12 10 to <br /> -1194 feet (Figure 2) Recent groundwater concentrations of TPHg and benzene are <br /> shown in Figure 3 <br /> FIELD ACTIVITIES <br /> To further evaluate the vertical and lateral extent of petroleum hydrocarbons in soil and <br /> I groundwater, Shaw installed one off-site cross-gradient well, one off-sitedowngradient " <br /> well, and one on-site dual completion well To evaluate remedial alternatives to <br /> complement or replace the existing SVE system for remediating groundwater at the site, <br /> Shaw conducted a groundwater extraction and air sparge tests to judge their feasibility <br /> Prior to the initiation of fieldwork, drilling permits were obtained from the SJCEHD, <br /> and an encroachment permit was obtained from the City of Stockton Copies of the <br /> permits are included in Attachment A Underground Services Alert (USA) was notified <br /> at least 48 hours prior to the commencement of field activities, and a private subsurface <br /> utility locating service was contracted to locate subsurface utilities at the boring <br /> locations <br /> i <br /> w <br /> 11SACRFPi1COMMONIsacDP120031Pr�188018800391 A Sae doc <br />