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ARCADIS Ms. Amaru <br /> June 1, 2010 <br /> Background <br /> PG&E discovered apparent petroleum-impacted soil during renovation activities at <br /> the site in December 2009. The impacted soil was removed, though the excavation <br /> was stopped pending additional soil characterization to delineate the area of impacts. <br /> The excavated area measures approximately 40 feet long by 25 feet wide by 6 feet <br /> deep. PG&E collected two representative soil samples from the excavation area, and <br /> the results indicated concentrations of total petroleum hydrocarbons (TPH) as diesel <br /> above the RWQCB, San Francisco Bay Region Environmental Screening Level <br /> (ESL) (RWQCB, 2008). <br /> Soil Sampling Activities <br /> Based on the results of the samples collected by PG&E, ARCADIS (on behalf of <br /> PG&E) prepared a work plan for soil sampling and removal (ARCADIS, 2010). The <br /> purpose of the soil sampling was to delineate the horizontal and vertical extent of <br /> petroleum-impacted soil. Additional soil was also proposed for removal as necessary. <br /> In April 2010, the soil sampling task was completed to define the extent of impacted <br /> soil. A total of 17 step-out soil borings (12 primary and 5 contingency)were <br /> advanced around the existing excavation to a total depth of 8 feet below ground <br /> surface(bgs) using a hand auger. One additional contingency boring (SB-15)was <br /> advanced using a hand auger to 2 feet bgs. The primary soil borings (SB-01 through <br /> SB-12)were advanced near the edge of the existing excavation, and the contingency <br /> soil borings (SB-13 through SB-18)were advanced approximately 10 to 13 feet from <br /> the existing excavation (Figure 2). With the exception of boring SB-15, samples were <br /> collected from each boring at depths of 2, 4, 6 and 8 feet bgs. Table 1 summarizes <br /> the selected analyses for each sample and identifies which samples were considered <br /> primary and contingency samples. The complete laboratory reports are presented in <br /> Attachment A. <br /> All primary samples were analyzed for the following: <br /> • TPH as gasoline by United States Environmental Protection Agency (USEPA) <br /> Method 8015B (M) <br /> • Benzene, toluene, ethylbenzene and xylenes(BTEX) by USEPA Method 8021 B <br /> • TPH as diesel by USEPA Method 8015B (M) <br /> Page: <br /> 2/8 <br />