SITE INFORMATION AND CORRESPONDENCE

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V 1117 Lone Palm Avenue,Suite 201 Modesto,California 95351 ATC 209-579-2221 Shaping the Future Fax:209-579-2225 1� The only well located downgradient from the site was a groundwater monitoring well located on the corner of North Wilson Way and East Harding Way, however this well was destroyed in —' 1992. The remaining twelve wells discovered during the well survey are located either upgradient or crossgradient from the site and are more than 1,000 feet from the site or have been destroyed. Based on this information, it was ATC's judgment that it is unlikely that these wells / have been impacted by petroleum hydrocarbons from the site. V Criterion 5: Pollutants remaining in groundwater do not create or threaten to create risk to human health and safety,or to future beneficial use(s)of the groundwater. Patterns of existing and future demands for usable water resources in the area must be considered in determining what period of time is reasonable to reach non-detectable (or background)concentrations. V In ATC's Site Conceptual Model dated March 2008, the following potential exposure pathways were evaluated: DIRECT CONTACT WITH SOIL - Gasoline impacted soil beneath the site exists beneath an asphalt paved parking lot.No direct contact with the impacted soil is expected without removing I/the paving and excavating the soil. DIRECT CONTACT WITH GROUND WATER — On January 10, 2008, groundwater in the monitoring well network was measured at an average depth ranging from 38.67 to 41.24 feet bgs. Access to the wells is protected by bolted metal well boxes and locking well caps. b/OFF-SITE MIGRATION POTENTIAL TO DRINKING WATER - ATC reviewed the San Joaquin County Public Health Services Environmental Health Division (PHS/EHD) groundwater well construction logs, Department of Water Resources (DWR) groundwater well construction logs, and conducted a site walk in the vicinity of the site to identify any groundwater wells located within 2,000-foot radius of the site. The search revealed fourteen wells located within v approximately 2,000 feet of the site. None of the fourteen wells are located within 500 feet of the site. Based on ATC's current work at the project site,the regional groundwater gradient is to the north-northeast The well located at the northeast corner of the State Hospital,is the closest to the site (within approximately 800 feet west). According to the well log, the well is approximately 250 feet deep and supplies irrigation water to the State Hospital. The first screen interval in this well is from 79 to 83 feet below ground surface(bgs). The well is also screened from 188 to 1.91 feet bgs, 194 to 220 feet bgs, and 240 to 250 feet bgs. Because this well is located up gradient from the site, it is ATC's judgment that it is unlikely that the well has been impacted or is threatened by petroleum hydrocarbons from the Eggiman property site. The only known well located down gradient from the site was a groundwater monitoring well located on the corner of North Wilson Way and East Harding Way,but this well was destroyed in 1992. The remaining twelve wells discovered during the well survey are located either up gradient or cross gradient from the site and are more than 1,000 feet from the site or have been destroyed. S:Enviromental\22493\Reports\Eggiman Closure Report.doc 10 r J