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U-Haul 4709-50 Blaes Envirannrenral Additional Site Characterization monitoring wells The two northernmost wells defined the lateral extent of oun impacted p groundwater Results also indicated that elevated hydrocarbon concentrations were present in groundwater from the off-site monitoring well (MW-7) Iocated approximately 200 feet south of the former dispenser area 1 5 2 CONCLUSIONS OF RECENT INVESTIGATION ' 5 2 1 Jjydrocarbon5 in Soil Based on results of the direct-push and cone-penotrometer soil sampling program, Blaes Environmental has ' defined the probable lateral and vertical extent of hydrocarbons in soil This investigation involved collecting soil samples within saturated soil to approximately 126 feet bgs or approximately 77 feet below ' the current groundwater interface Direct-push and cone-penotrometer soil sampling technology were determined to be the best methods for preserving soil sample integrity when sampling this far below groundwater Blaes Environmental installed six boreholes for soil sample collection at locations shown on ' Figure 4 Soil samples were also collected from soil bonngs to complement data collected from the direct- push/cone-penetrometer boreholes These locations included the central portion of the hydrocarbon plume (DP-1, DP-2 and MW-3a) and the lateral portions of the plume (DP-3, DP-4, DP-5, DP-6, MW-4a, and MW-1 a) Field descriptions of soil collected from the direct-push boreholes and soil borings provided data to create two cross-sections of the site(Figures 5 and 6) Both cross-sections indicate the soil beneath the site is not layered into easily definable stratigraphic horizons Rather, soil types vary with depth and between Ilocations Soil beneath the site consist of silty sand and sand interbedded with sandy silt, silt and sandy clay One visible trend with cross section A - A' indiactes that soil on the eastern portion of the site is Imore clayey than the western portion of the site The extent of hydrocarbons in soil is discussed below I 5 2 1 1 our e Area Uysirocarbons The source area of the hydrocarbon plume is located near borehole Iocations DP-1 and DP-2 Analytical results indicate that TPHg concentrations in soil from DP-2 were greater than 1,000 mg/Kg at depths of 10 to 74 feet bgs Soil collected at approximately 29 feet bgs contained 21,000 mg/Kg TPHg Field observations of this sample indicated that apparent free-phase hydrocarbons saturated the sample The apparent source area of hydrocarbons in soil is also defined by plotting the vertical representation of soil sample analytical results(Figure 8) The source area appears to be the former western dispenser island 2I