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Site Background Information: Vanco Truck &Auto Plaza Page 4 of 6 serving as a preferred migration .route, and could potentially allow migration of large contaminant masses over-great distances. The model presented is interpretational and will be modified as more data is collected.The eight vertical zones are identified;as follows (dep hs are approximate and can vary by several feet•across the site): Vadose/FirstWaterzone-This zone extends from urface grade to approximately 20 feet= bsg. Static water-is at 20 feet,bsg in the monitoring wells, however, the first saturated soil samples were collected at 30 feet,bsg. This indica es that the water table is confined by. the overlying fine-grained materials. This zone is characterized by moderate pore pressures. Hydrogeologic Unit 1,(HU1)- Extending from 20 feet-to approximately 30 feet bsg, HU1 is comprised predominantly of� sandy silt; claye silt. and silt: Dominant hydraulic conductivities,based on CPT soil behavior types(S Ts),range between 1 x1-0-6 and 1 x10-8 centimeters per second;(cm/s)for,silty to clayey 4:)e soils. This interval is characterized by generally moderate pore pressures. Hydrogeologic Unit 2 (HU2)-At the top of the cu nt saturated zone, HU2 extends from 30 feet-to approximately 38 feet bsg andIs composed of silty sand to sand type soils. Hydraulic conductivities for-HU2 typically vary betNeen 1 x10-2 and 1 x 10-5 cm/s. HU2 is characterized by generally lower pore pressures and is classified as a flow unit. Hydrogeologic Unit-3 (HU3)- HU3 extends from 3f feet to approximately 45 feet bsg and is composed primarily of4stiff;fine-grained soils,-cla fey silts,silts,and silty clays. Hydraulic conductivities for,these-soil types gpnerally,rang between 1x104 and 1x10 cm/s for clays, silts, and stiff,,fine-grained soils. HU3-is ch iracterized by varying pore pressures ranging between moderate and high and is identif Bd as a confining layer. Hydrogeologic Unit 4,(HU4)- HL141extends from 4E feet bsg to approximately 50 feet bsg, and is composed of silty sand to sand type soils. Hy4 Iraulic conductivities for HU4generally range between 1x10'2 and 1x10-5 cm/s. HU4,,is aracterized by generally lower pore pressures and is classified as a flow unit. Hydrogeologic Unit 5 (HU5)-Extending from 50 feet to approximately 70 feet bsg, HU5 is composed predominantly of stiff,fine-grained clayE y silts, silty clays, and clay. A thin silty sand to sand type soil is encountered at appro imately 58 to 62 feet bsg and has characteristically low hydraulic conductivity. Hy raulic conductivity generally ranges between 1x10-5 and 1x1015 cm/s for clays, silts and stiff, fine-grained soils. HU5 is characterized by varying pore pressures varying from moderate to very high, and is identified as a confining layer. Advanced GeoEnvironmentaL Inc.