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08 November 2005 • AGE-NC Project No. 98-0481 ' Page 7 of 8 appeared to raise a significant concern or threat to human health. 5.0. CONCLUSIONS t Based upon data collected during the site investigation activities, AGE concludes the following: p g ' Based on soil sample analytical results,relatively low levels of petroleum hydrocarbons were reported directly beneath the former dispensers and associated product piping. Results from soil samples collected during the UST removal activities indicated detections of petroleum hydrocarbons at 4 and 8 feet bsg in the former dispenser area. Subsequently,results from soil boring B-1 g, located between the two former dispenser locations, indicate that petroleum impacts from the dispensers did not extend to a depth of 9.5 feet bsg. No indications of hydrocarbon impact to soil were observed or reported for soils encountered in soil borings SB-1, SB-3, SB-4, or B-1, located around the former fuel dispenser island. tThe amount of gasoline released from the line rupture during the drilling of boring SB-2 in 1999 is estimated to be between 3.7 and 6.9 gallons; however,a portion of that would have evaporated during the several days needed to repair the product line and re-gave the area. In 10 addition, soil samples subsequently collected from borings(SB-3 and SB-4),located within 8 and 12 feet of the spill site,had no reported detections of petroleum hydrocarbons,which indicates that impacts did not migrate significantly vertically or lateral from the spill site (Figure 3 and Figure 4). As shown on Figures 6, 7, and 8, the extent of petroleum hydrocarbon-impacts to soil do not appear to extent beyond the immediate vicinity ofthe fuel ' dispenser island. • It is highly unlikely that the low petroleum hydrocarbons-impacts to soil detected at a depth of 7.5 feet bsg in boring HA-1 would migrate vertically over 50 feet, through a thick layer of fine-grained soils,and impact the initial ground water-bearing unit which appears to exist approximately 60 feet bsg. Additionally, when considering the a small volume of release, dispersion, attenuation, the existing hard pans at 8-10.5 and 23 feet bsg will significantly limit the potential for vertical migration of impacts. • The amount of TPH-g in soil,based on the estimated lateral and vertical extent of the TPH-g ' plume (Figures 4 and 7), was calculated to be approximately 6.28 lbs, or approximately 1.0 gallon (Appendix Q. ' Ground water sample SB4-H2O,which was collected approximately 12 feet from the source of the release during the advancement of soil boring SB-2, indicates that there are no petroleum-hydrocarbon impacts to ground water. • The closest potential receptor is a municipal well (Identified as municipal well#1) located at the end of Roosevelt Street, approximately 1,700 feet southeast from the site. Due to the Advanced GeoEnvironmental,Inc.. 1