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Ripona Market October 28,2004 Corrective Action Plan unstable and often flowed into the borehole under hydraulic pressure The "heaving sands" flowing into the open augers restricted the insertion of the drill bit and sampling tools As noted on the logs "heaving sands" prevented the collection of soil and water samples at several of the planned intervals Groundwater flow has been consistently to the northeast with a shallow gradient as shown in the Figure 4 August 2004 map of groundwater elevations Groundwater elevations have fluctuated between 35 and 42 feet A cumulative ' hydrograph of the site groundwater elevations is shown in Figure 8 3.0 Contamination Characteristics 3.1 Soil Contamination ' Gasoline hydrocarbons and aromatic compounds were not detected in any of the soil samples collected in the exploratory bonngs Moderate concentrations of fuel oxygenates were detected in soil samples collected at depths of 25 and 30 feet in bonngs located in the vicinity of the former underground storage tanks An MTBE contamination cross section is shown as figure 6 ' 3.2 Groundwater Contamination Very low concentrations of toluene were detected in Boring B2 (0 5 ug/l @ 60 10 ft), Boring B3 (1 1 ug/l @ 38 ft ) and Bonng B4 (1 9 ug/1 @ 45 ft ) Very low concentrations of gasoline were detected in Boring B4 (0 07 mg/l @ 45 ft) I Moderate concentrations of MTBE were detected in a water sample collected from well MW-2 located adjacent to the former underground storage tanks Trace concentrations of MTBE were detected in a water sample collected from the deep I well, MW-4 MTBE groundwater contamination is shown in map view in figure 6 and in cross section in figure 4 MTBE groundwater contamination is limited to the vicinity of well MW-2 and defined vertically at a depth of 55 to 60 feet vertically 3.3 Contaminants of Concern Contaminants of concern have been identified as MTBE probably sourced from the former underground storage tank as been identified as a potential carcinogen and has demonstrated taste and odor impacts on water quality Laboratory analyses have consistently reported MTBE with the highest concentration of all analytes All plume modeling and fate and transport modeling was conducted using MTBE 3.4 Contaminant Distribution MTBE contamination is limited to in area immediately around the former underground storage tanks Soil impacts were detected at the water table in a 7