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31 January 2013 AGE-NC Project No. 02-0926 Page 7 of 21 in the 30 to 60 foot interval and at maximum concentrations of 50 mg/kg benzene, 250 mg/kg toluene, 120 ethylbenzene and 630 mg/kg xylenes (B5-33). Analytical results of soil samples collected from 30 to 60 feet bsg are summarized in Table 1. The estimated area of impact within the above zone is illustrated in cross sectional view in Figures 5 and 6, and the lateral maximum extent is illustrated in Figure 8. 4.3. ADSORBED PETROLEUM-IMPACT: 60'-75' BSG Based on soil samples collected at the site between 60 and 75 feet bsg (within the historic deep saturated zone), AGE has modeled the estimated lateral extent of adsorbed hydrocarbon impact within the above sampling interval. Based on these sampling results the adsorbed soil plume appears to limited to areas surrounding boring MW6 and terminates just below 60 feet bsg. TPH-g and TPH-d were reported at the 60-foot sampling depth at concentrations of 49 mg/kg and 18 mg/kg, respectively. BTEX constituents were reported at the 60-foot sampling depth at low concentrations of 1.6 mg/kg benzene, 0.49 mg/kg toluene, 6.0 mg/kg ethylbenzene and 0.680 mg/kg. Vertically, the adsorbed soil plume appears to be defined by samples collected from boring MW6 at depths of 65, 70 and 75 feet bsg; constituents of concern were not reported above laboratory reporting limits in boring CPT-3 at depths of 65 and 75 feet bsg, respectively. Analytical results of soil samples collected from 60 to 75 feet bsg are summarized in Table 1. The estimated area of impact within the above zone is illustrated in cross sectional view in Figures 5 and 6, and the lateral maximum extent is illustrated in Figure 9. 5.0. GROUNDWATER MONITORING AND SAMPLING PROGRAM Between February 2004 and July 2012, twenty-three (23) ground water monitoring events were performed at the site to monitor dissolved petroleum hydrocarbon concentrations in ground water and to characterize ground water flow direction and gradient on the site. Since initiation of ground water monitoring program at the site in February 2004, depth to ground water has ranged between approximately 32 and 44 feet bsg; ground water elevations have ranged from approximately 14 and 26 feet below mean sea level. Ground water flow direction has generally fluctuated from north to south to northeast to southwest at generally flat hydraulic gradients. Selected historical groundwater flow direction maps have been included in Appendix D. A map illustrating the most recent ground water flow direction and gradient has been included as Figure 10; included on the ground water elevation map is a rose diagram depicting historical ground water flow directions. Advanced GeoEnvironmental, Inc.