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06 June 2003 AGE-NC Project No 98-0433 Page 3 of 4 This well is the only municipal well within 2,000 feet of the site, with the other wells located more than 2,000 feet southeast of site The distance of this well from the subject site limits its potential to be adversely impacted by the release of petroleum hydrocarbons on the site Threatened Well As described below,the domestic well for the Jimco Truck Stop is located within the margin of the MTBE ground water plumes, in a up-gradient direction from the site, and is therefore the well most likely to be effected by the release of petroleum hydrocarbons on the site 4.0. SITE MODEL Based on the data developed to date,including all soil borings,monitoring wells installed,AGE has developed a site model for the release, migration and distribution of the contaminants in the subsurface as described below • A release of petroleum hydrocarbons occurred from the underground storage tank located near the northwest corner of the truck wash area The duration/frequency and intensity of the • release is uncertain Three USTs and associated product distribution system were removed from the site between July and September 1998 Petroleum hydrocarbons in soil were detected in the north end of the former gasoline UST and throughout the dispenser locations e Silty sand and sand with a tan or gray color, apparently depending on hydrocarbon impact, was generally encountered from a depth of approximately 5 feet to 10 feet bsg Gray silty clay was present at depths between 10 and 15 feet bsg Sand was encountered at depths of 15 and 25 feet bsg in various locations, while a coarse sand appears to extend northwest toward from the former UST area at a depth of 25 feet bsg Inter-layered silt and sand extend to a depth of 40 feet bsg in the former UST area, presenting no significant vertical barrier present at the former UST area Soil bonngs are depicted in Appendix A Cross sections A-A' and B-B' (Figure 3) illustrate the soil profile encountered in the borings/wells and the estimated extent of impacted soil in the fibriner vicinity of the USTs • Based on soil samples analyzed, impacted soil is present below the current ground water table, due to historically lower ground water elevations at the site during which time a portion of the unauthorized hydrocarbon release occurred The most intensely hydrocarbon- impacted soil was encountered in the area of the former USTs Soil contaminated with petroleum was limited to depths of 30 feet bsg, except for fuel additives, and the highest hydrocarbon concentrations were encountered at depths of 10 to 20 feet bsg However, MTBE was detected at reduced concentrations in soil collected from a depth of 35 feet bsg near the former UST area Analytical results of soil samples collected at the site are summarized on the attached Tables Advanced GeoEnvironmental,Inc