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ARCADIS Ms.Amaru <br /> February 19, 2010 <br /> Background <br /> PG&E discovered apparent petroleum-impacted soil during renovation activities at <br /> the site in December 2009. Plant renovation activities included the demolition of an <br /> aboveground lube oil tank and associated secondary containment berm. Upon <br /> removal of the secondary containment berm, an area of discoloration was observed <br /> on the underlying soil. PG&E over-excavated and removed approximately 90 cubic <br /> yards of impacted soil.The excavation was stopped pending additional soil <br /> characterization to delineate the area of impacts.The excavation area is rectangular <br /> in shape and measures approximately 40 feet long by 25 feet wide by 3 feet deep. <br /> PG&E collected two representative soil samples from the excavation area on <br /> December 10 and 11, 2009, and submitted them to California Laboratory Services, , <br /> a California Department of Public Health-certified analytical laboratory, located in <br /> Rancho Cordova, California for analysis of the following parameters: <br /> • Total petroleum hydrocarbons(TPH)gasoline range <br /> • Benzene,toluene, ethylbenzene and xylenes(BTEX) <br /> • TPH diesel range <br /> • California Assessment Manual (CAM) 17 total metals <br /> • Polychlorinated biphenyls(PCBs) <br /> TPH gasoline was detected at 11 and 19 milligrams per kilogram (mg/kg). Benzene <br /> was detected in one of the two samples at a concentration of 0.0061 mg/kg.Toluene <br /> was not detected in either sample. Ethylbenzene was detected at 0.015 and 0.020 <br /> mg/kg, and total xylenes were detected at 0.015 and 0.018 mg/kg.All concentrations <br /> of TPH gasoline and BTEX were below their respective California Regional Water <br /> Quality Control Board (RWQCB), San Francisco Bay Region Environmental <br /> Screening Levels(ESL)(RWQCB, 2008). TPH diesel was detected at 2,200 and <br /> 2,600 mg/kg,which is above the ESL of 83 mg/kg. Of the 17 metals analyzed, seven <br /> were not detected in either sample.Arsenic, barium, chromium, cobalt, copper, lead, <br /> nickel, silver,vanadium and zinc were detected in soil; however, only the results for <br /> arsenic and vanadium exceeded their respective ESLs of 0.39 and 16 mg/kg. PCBs <br /> were not detected above the laboratory reporting limit in either sample.The <br /> laboratory reports from the December 2009 sampling are included in Attachment A. <br /> Page: <br /> 2/7 <br />