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URS Mr. Ray Von Flue San Joaquin County Environmental Health Department January 23, 2003 Page 2 Soil Sampling beneath Product Piping On August 15, 2002, the dispenser islands and the associated product piping were excavated and removed. After the removal, Stratus Environmental collected three soil samples from beneath the product lines (designated L-1-5 through L-3-5.5). Sample locations are shown on Figure 2. Samples were collected from depths of approximately 5 feet below ground surface with a slide hammer. The slide hammer was thoroughly decontaminated between sample locations. Field and laboratory procedures are presented as Attachment C. Field notes are included as Attachment C. Soil Sampling—USTs and Dispensers On October 22, 2002, two gasoline USTs were excavated and removed from the site. URS collected a total of six soil samples (designated PB-1 through PB-6) from the bottom of the tank pit at the north, center, and south portions of each former UST location (Figure 2). The bottom of the tank pit was approximately 18 feet below grade. Soil samples were collected from the tank pit by pushing a brass tube into a fresh backhoe bucket of soil. One soil sample was collected beneath each of the four dispenser islands with a slide hammer. Four composite soil samples were collected by URS from the soil stockpile and analyzed on an accelerated 48-hour turnaround time. Soil Sample Analysis and Results Soil samples were analyzed for total petroleum hydrocarbons as gasoline (TPHg)by U.S. Environmental Protection Agency (EPA) Method 8015; benzene, toluene, ethylbenzene, total xylenes (BTEX), and methyl cert-butyl ether (MtBE) by EPA Method 8021; and fuel oxygenates (tert-butyl alcohol [TBA], MtBE, di-isopropyl ether [DIPE], tertiary amyl methyl ether [TAME], ethyl tertiary butyl ether [ETBE], ethylene dibromide [EDB], and 1,2-dichloroethane [1,2-DCA]) by EPA Method 8260B. Soil stockpile samples were also analyzed for total lead by EPA Method 6000/7000 Series Methods. No analytes were detected above reporting limits in the seven soil samples collected from below the dispenser islands and the piping. No analytes were detected above reporting limits in the six soil samples collected from the bottom of the UST excavation, with the exception of TBA, which was reported at 1.6 milligrams per kilogram (mg/kg) in PB-6. The results of confirmation soil samples are presented in Table 1. Laboratory analytical reports and chain-of-custody documentation are presented as Attachment E. Because impacted soil was not observed in the UST excavation, over-excavation of the tank pit was not conducted. Samples of the excavated material (SP-14, SP-5-8, SP-9-12, and SP-13-16) indicated that it was not impacted with petroleum hydrocarbons, BTEX, fuel oxygenates, or lead (Table 2). Therefore, the excavated material was used to backfill the tank pit. K:U5 BP ARCO\00434\Quarterly\UST Removal\00434 UST Removal 2nd report.doc