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C A M B R I A PRIVATE WATER WELL SAMPLING At the direction of EHD, Cambria collected a groundwater sample from the San Juan Vista Mobile Home Park well located approximately 600 feet southeast of the subject site. Cambria received verbal permission from the on-site manager of the mobile home park to collect a water sample on August 20, 2003, and collected the water sample that day. The approximate location of the mobile home park well is shown on Figure 3. At the time of sampling,the well pump was not operating, therefore the water sample could not be collected from the sample port located at the well head. The water sample was collected from the tap in the laundry room, which was the © tap located closest to the well. The water sample was analyzed for total petroleum hydrocarbons as gasoline (TPHg), benzene, toluene, ethylbenzene, and xylenes (BTEX), the seven fuel oxygenates, and for lead scavengers (1,2-DCA and ethylene dibromide [EDB]). None of these compounds were detected in the groundwater sample collected from the mobile home park well. The lab report for this sampling event is included in Appendix A. TECHNICAL RATIONALE FOR PROPOSED SCOPE OF WORK • 1,2-DCA has been detected in groundwater beneath the subject site at concentrations as high as 1,640 ppb in grab groundwater samples from borings. 1,2-DCA has been detected in all site groundwater monitoring wells at concentrations ranging from 8.06 to 540 parts per billion(ppb). • The source of the 1,2-DCA has not been verified, however since gasoline previously contained 1,2-DCA (prior to 1991), EHD has directed Shell to investigate the vertical and lateral extent of 1,2-DCA in the vicinity of the subject site. • As discussed in our June 27, 2003 work plan, to determine if the 1,2-DCA originates from the northern dispenser island, Cambria proposes collecting soil samples in the vicinity of boring SB-4 to evaluate the lead levels in the soil. Elevated lead levels in the soil would suggest the fuel release contained lead scavengers, including 1,2-DCA. However, we recognize that finding background levels of lead in the soil does not prove the 1,2-DCA did not originate from the fuel release at this site. • Cambria proposes performing a record search of the area surrounding the subject site to identify any possible offsite sources of 1,2-DCA. 0797 2