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04 January 2000 AGE-NC Project No. 95-0106 Page 3 of 5 • Petroleum hydrocarbons may be migrating as dissolved constituents through clay-rich soil at shallow depths, approximately 5 to 10 feet bsg, in the shallow saturated zone and capillary fringe zone; or • Petroleum hydrocarbons may be migrating as dissolved constituents through sandy soil layers lying 10 to 25 feet bsg. In the former case, a greater potential for human exposure may be anticipated. Conversely,the latter case would demonstrate a natural barrier, approximately 10 feet thick, to human exposure. In addition, migration through the upper fine-grained unit would retard the spread of hydrocarbons, while migration via the lower coarse-grained unit would facilitate lateral spread of hydrocarbons, potentially impacting a greater volume of ground water. AGE proposes the following scope of work to test the two scenarios, to properly assess the extent and magnitude of the plume of dissolved hydrocarbons, and to derive information to properly assess the risk posed by the presence of petroleum hydrocarbons in soil and ground water: • Advance two soil probe borings to approximately 18 feet bsg, collect continuous soil samples,collect ground water samples near the capillary fringe zone at approximately 6 feet bsg, and collect ground water samples from the deeper saturated zone, presumably in sandy soil, at 17.5 feet bsg. • Advance five soil probe borings to collect soil and grab ground water samples near the capillary fringe and in the deeper saturated zone as described above, to further assess the hydrocarbon-impacted ground water north of the former UST location. Figure 1 shows the proposed probe boring locations. • Advance one hand auger boring to the capillary fringe zone, estimated to lie at approximately 6 feet bsg,to collect one soil sample and grab ground water sample. The hand auger boring will not exceed a depth of 9 feet bsg. If soil or ground water samples from the hand auger boring yield field indications of petroleum hydrocarbons, a second hand auger boring (the contingency hand auger boring on Figure 1)will be advanced approximately 30 feet further down-gradient for similar soil and ground water sampling. • Establish a vertical sequence of soil lithology to delineate potential permeable pathways (sandy soil) with the continuous cores. • Analyze the soil and ground water samples for TPH-g,BTEX and oxygenated fuel additives (DIPE, ETBE, MTBE, TAME and TBA) in accordance with EPA Methods 8015M/5030, 8020/602 and 8260M, respectively. Advanced GeoEnvironmental,Inc.