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of the site (EMCON map ID #2). Based on a reconnaissance of the area by Stratus personnel, EMCON well #2 appears to be situated within a fenced compound posted by California Water Service Company. Stratus personnel were unable to verify installation of a well at the EMCON map ID #4 location west-southwest of the site. An industrial well was identified approximately 1,800 feet southeast of the site (EMCON map ID 93). Del Monte Survey: The Del Monte survey identified a California Water Service Company municipal supply well (Del Monte Map ID #5) approximately 500 feet east of the former Apache Plastics site. The Del Monte well survey information indicates that this well was installed in 1943 and deactivated in 1978. Given the reported well location and installation dates, Del Monte Map ID well #5 appears to be the same well as EMCON Map ID 92. The Del Monte survey also identified a water supply well in the vicinity of A Street and I lth Street (Del Monte Map ID #23). This well is situated approximately 2,000 feet southwest of the Apache site. Discussion Given the distance of water supply wells from the site, it appears unlikely that petroleum hydrocarbons originating from the former Apache Plastics facility threaten off-site water supply wells. The only downgradient well in close proximity to the site appears to be the California Water Service Company well situated east of the site. This municipal well was apparently deactivated in 1978. Based on our understanding of the extent of dissolved petroleum hydrocarbon impact, the plume originating from the former Apache Plastics facility does not appear to extend off-site east of the property. It is our understanding that surface water is currently utilized to supply the City of Stockton's municipal water source. 6.3 Utilities All utilities are delivered to the former Apache Plastics building via subsurface routes. There are no on-site septic or water disposal systems operated on the property. Given historical depth to water data for this site, it appears unlikely that subsurface utility trenches act as preferential pathways for hydrocarbon migration. It might be possible, however, for hydrocarbon vapors to accumulate in the utility trenches. Construction workers excavating these utilities could potentially be exposed to hydrocarbons via this route. Similarly, if there are any subsurface manholes/vaults associated with these utilities, hydrocarbon vapors could potentially accumulate in the vaults. Workers excavating in these areas should use appropriate monitoring and personal protective equipment in the event that hydrocarbon vapors could be encountered. Based on our field observations while completing intrusive activities in the shallow subsurface at the site, the potential for significant levels of hydrocarbon vapor accumulation in the utility trenches in the site vicinity appears low. K;\APache Plastics�Reportstiapache-sem-assessment report2006.doc Page 17 STRATUS