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19 January 2012 <br /> AGE-NC Project No. 11-2006 <br /> Page 6 of 7 <br /> Soil vapor analytical results are summarized in Table 4. Laboratory analytical results are <br /> included in Appendix C. <br /> Geophysical Survey <br /> The geophysical survey did not identify any underground structures indicative of USTs, <br /> clarifiers or other possible contaminant sources. <br /> CONCLUSIONS <br /> Based on the data collected from this investigation, AGE concludes: <br /> • Petroleum hydrocarbon constituents were not detected in analyzed soil samples <br /> during the additional investigation performed in January2012. Selected metals were <br /> detected in both soil samples, but were below commercial environmental screening <br /> levels for deep soils in areas where ground water is a potential drinking water <br /> source. <br /> • Petroleum hydrocarbon constituents were not detected in grab ground water <br /> samples collected during additional site assessment activities. Based on current and <br /> historical sampling results, shallow petroleum-impacted ground water appears to be <br /> limited to an area south of the current on-site building near boring B1. The vertical <br /> limits of the impact have not been defined. The lateral limits of shallow impacted <br /> water are marginally defined. <br /> • Gasoline range hydrocarbons (TPH-g) were detected in both shallow soil vapor <br /> samples (V1 and V2) collected at the southern edge of the on-site building. The <br /> concentrations reported at both locations are below commercial soil gas <br /> environmental screening levels of 29,000 pg/m3; reported concentrations are below <br /> residential soil gas screening levels at V2, and slightly above at V1. <br /> • Results from geophysical surveying performed in December 2011 showed no <br /> indication that an underground storage tank currently exists at the property <br /> (Appendix B). <br /> Advanced GeoEnvironmental,Inc. <br />