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r' <br /> Appendix B - Site Background Information <br /> Former Fisco Warehouse <br /> Page 6 of 6 <br /> generally has been towards the northwest(nine times) at gradients ranging between 0.001 ft/ft and <br /> 0.008 ft/ft; ground water.flow was towards the south four times at gradients between 0.01 ft/ft and <br /> 0.05 ft/ft, and twice towards the east or northeast at gradients between 0.00 l,ft/ft and 0.04 ft/ft. <br /> Releases of petroleum hydrocarbons occurred from. the on-site USTs. Once released to the <br /> subsurface,the contaminants migrated through the fine grained unit directly below the UST area to <br /> a vertical depth of approximately 15 feet bsg, at which point the contaminants encountered a more <br /> porous sand unit and began to migrate laterally as well as`vertically: The lateral migration was <br /> further increased when ground water was encountered(which has been recorded at 33feet to 62 feet <br /> bsg during the investigation); the direction of lateral .migration was dominantly towards the <br /> northwest, in the preferred ground water flow direction. <br /> Significant petroleum-hydrocarbon impact to.soil in the vadose zone is present in borings B 1, B3, <br /> B5, MW1, and MW2, in the area of the former USTs. TPH-g, TPH-d and MTBE are present at <br /> maximum concentrations of 14,000 mg/kg(135-25),.12,000 mg/kg(B3-10 and-15)and 1,100 mg/kg <br /> (B1-30), respectively. Most of the contamination appears to reside above the top of the fine grain <br /> layer,at approximately 50 to 55 feet bsg;currently the extent of the soil contamination is completely <br /> within the vadose zone. <br /> The vertical extent of ground water is defined -near the UST. area by MW-8, ground water <br /> contamination does not extend below 90 feet bsg. The lateral extent of petroleum-impacted ground <br /> water was defined by wells MW-4 through MW-7,but these wells are now intermittently dry.With <br /> the exception of two detections of 1,2-DCA in well MW-4,petroleum hydrocarbons have not been <br /> detected in wells peripheral to wells MW-1 through MW-3, located in the UST area, since third <br /> quarter 2001. <br /> For additional information please refer to the AGE prepared Interim Corrective Action Plan,dated <br /> 20 January 2005. <br /> 1 <br /> Advanced GeoEnvironmental,Inc <br />