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Serit By; BASELINE; 510 420 1707; Nov-9-99 16:30; Page 22129 <br /> the PRG appeared to have been localized around boring WBSB9 (Black& Veatch, 19988) (Table <br /> 1). <br /> Analytical results for sediment samples were also compared to EPA Region IX PRGs. Based on this <br /> comparison, four SVOCs [benzo(a)pyrene, benzo(a)fluoranthene, benzo(a)anthracene, and <br /> inderno(1,2,3-cd)pyrene] were detected in sediment samples above the respective residential PRGs. <br /> Arsenic, iron, and lead were also detected in one sample above the respective PRG. The presence <br /> of SVOCs in, sediment may be attributed to treated wood pilings in the Channel; removal of the <br /> pilings would remove this possible source. Detected concentrations of metals in sediments may be <br /> either naturally occurring or the result of historic site uses that are typical of the entire waterfront <br /> (Black& Veatch, 1998a) (Table 3). <br /> Former Shell Station/Bridgestone Tire and Automobile Repair Facility Investigations <br /> Former operation of the gasoline USTs at the service station/repair facility has resulted in <br /> contamination of soil and groundwater at the site with gasoline and associated aromatic <br /> hydrocarbons.A groundwater extraction system and soil vapor extraction system were installed to <br /> remediate this contamination. Soil and groundwater sampling results indicated that the groundwater <br /> extraction,soil vapor extraction,and natural attenuation process have reduced the concentration of <br /> petroleum hydrocarbons beneath the site (Enviros, 1997). <br /> MTBE hu been increasing at the Weber Block property over time. Shell discontinued selling <br /> gasoline in 1981 prior to the use of MTBE. Based on the increasing MTBE concentration trend and <br /> time period during which gasoline was stored at the site,Enviros(1997)concluded that MTBE.was <br /> originating from an off-site source. <br /> The source of the halogenated volatile organics on-site could have been related to the former waste <br /> oil tank. While Shell does not have any soil data for halogenated volatiles in the vicinity of the <br /> former waste oil tank,the distribution of HVOCs in groundwater indicated that the former waste oil <br /> tank was not the source of the HVOCs. Groundwater samples collected from the closest wells to the <br /> former waste oil tank (MW-1 and MW-5) were reported below laboratory reporting limits for <br /> HVOCs (Enviros, 1997). Halogenated volatiles have been reported in groundwater at the off-site <br /> ARCO facility. <br /> OFF-SITE <br /> Former ARCO Station Investigation <br /> Soil and groundwater investigations at the former ARCO site confirm that this is a possible source <br /> of contamination of petroleum hydrocarbons, BTEX, MTBE, chlorinated solvents, and other <br /> organics. This site will undergo cleanup in the future. The cleanup will include any plumes that <br /> have migrated onto the Weber Block property,which is located hydraulically downgradient of this <br /> site (Brown, 1999). <br /> 973(i9gtk.pea.wpd-1119199 16 <br />