ARCHIVED REPORTS XR0000194 - Laserfiche WebLink

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R10/71-51-1C approximately 20,000 square feet at the groundwater interface The impacted sod, contaminated with gasoline-derived compounds which include benzene, toluene and xylenes has a volume of approximately 65,200 cubic yards Figures 26, 27, and 28 See Appendix J) resent zero concentration maps of benzene, 9 ( PP P toluene and xylenes, respectively, in the groundwater The maps indicate that the contamination generally moves in the northeasterly and southeasterly directions This distribution appears to be supported by the groundwater flow direction illustrated in Figure 29 (Appendix K) Based on the water level data collected on October 22, 1993, the groundwater elevation contour map is presented in Figure 29 (see Appendix K) The groundwater flow direction in the vicinity of monitoring well MW8 is to the west, in the vicinity of MW9 is to the east, and in the vicinity of MW1, MW2, MW3, MW4, MW10, MW14, and MW24 is to the north The area of the groundwater impacted by gasoline- derived contaminants which include benzene, toluene, and xylenes has an approximate length of 350 feet (from the north boundary to the south boundary) and a width of approximately 300 feet (from the east boundary to the west boundary) It occupies an area of approximately 60,000 square feet, or roughly one-third of the Shop 10 facility area Because the porosity of the soil is unknown and the depth of the contaminated groundwater area is not also known, an estimate of the volume of contaminated groundwater cannot be made Detailed evaluation of Remedial Action Options Identified the following alternatives that are recommended to be implemented in combinations o In Situ Containment by effectively capping the area to address privately the soil contamination issue and reduce contaminant infiltration into the groundwater The present worth cost estimate of this option is $103,000 during a five-year period operation o Pump and Treat with Air Stripping to remove/reduce groundwater contamination within the vicinity of the former underground fuel tanks Contaminated groundwater is pumped from one or more recovery wells and I channelled to a collection point The contaminated groundwater is then treated by air stripping Air stripping is a unit process in which water and air are brought into contact with each other for the purpose of removing volatile substances from the waste stream The treated groundwater is then disposed of into PO-TW, natural water, or recharged /irrigated on site The present worth cost estimate of this option is $ 966,000 during a five year period of operation 47