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' U-Haul#709-50 Additional Site Charactenzation ,Blaes Environmental indicates that (at 70 to 75 feet b s h g } hydrocarbons ocarbons in soil extend to the west toward borehole DP-6, approximately 55 feet from the apparent source area, and to the north toward borehole DP-3, approximately 20 feet from the apparent source area These two sample points define the lateral extent ' of hydrocarbons in soil Based on these results and the apparent shape of the hydrocarbon plume in soil, the eastern extent of hydrocarbons which extends off site, is likely similar to western extent ' The vertical and lateral extent of hydrocarbons in soil is also illustrated on Figure 7 This figure illustrates the soil boring locations along cross-section A - A' along with the soil sample analytical ' results Using the analytical results shown, the vertical boundaries of the plume can be traced The zone with TPHg concentrations greater than 1,000 mg/Kg includes soil within the area of boreholes DP-1, ' DP-2, and DP-5 42 CHDWAT R ITI N Groundwater conditions beneath the site were determined using groundwater elevation data, monitoring of groundwater dissolved oxygen, and groundwater sample analytical results The following sections describe results of groundwater monitoring and analytical results 4 2 1 Results of GroundwateLomto"2na IWith the installation of the eight new monitoring wells at the site, the groundwater conditions are more accurately represented Groundwater level measurements taken on February 8, 2000 indicated that the depth to groundwater across the site ranged from 44 83 feet below top-of-casing (btoc) at MW-413 to 46 43 feet btoc No free-phase hydrocarbons were observed during groundwater gauging Groundwater gauging data is presented on Table 5 The resulting groundwater elevations across the site ranged from -26 20 feet below mean sea level (bmsl) to -26 48 feet bmsl Based on these elevations, the groundwater flow direction was toward the north on the northern portion of the site and toward the south on the southern portion of the site (Figure 9) A variable groundwater flow direction is common with a generally flat groundwater gradient In addition to groundwater levels, Blaes Environmental collected in-situ dissolved oxygen level readings Dissolved oxygen levels are useful in determining biological conditions in groundwater Dissolved oxygen levels in the wells at the site ranged from 1 0% to 14 0% The two wells at the perimeter of the hydrocarbon plume (MW-5a and MW-8a) had the highest dissolved oxygen readings of 10 2% and i 17