ARCHIVED REPORTS_XR0002661 - Laserfiche WebLink

Home Browse Search

r September 18, 1996 Page 6 The vacuum radius of influence was estimated to be In excess of 25 feet, for Wells V-1 - through V-5 A subsequent vacuum radius of influence analysis was performed on Well MW-4,resulting in an estimated effective radius of 112 feet -During the SVE, program,`an estimated total of approximately 12,000 pounds (1,967 gallons) of petro- leum hydrocarbons were removed (Correctri,e Action Plan, PACIFIC, November 30, 1995) System operational data including influent concentrations, flow rates, and the operating time is presented in the table included in Attachment A The calculations for deterinirung TPPH-g mass in soil and groundwater utilized soil boring and analytical data to estimate the areal extent of the hydrocarbon plume Aver- age concentrations were applied to distinct cross sectional areas in order to arrive at the . total hydrocarbon mass both prior to and after SVE treatment Figures 3 through 5 depict soil conditions beneath the site prior to operation of the SVE system (November r 1990 - November 1992) .Figures 6 through 8 depict these conditions and show soil analytical data from soil borings and wells drilled after the operation of the SVE system ti Calculations for determining the TPPH'g mass in soil and groundwater before and after the operation of the SVE system are presented as Attachment A RESIDUAL PETROLEUM HYDROCARBONS IN SOIL Currently, residual petroleum hydrocarbons in soil occur below and northeast of the former UST cluster(installed in 1984) and adjacent product island The vertical and lateral extent of petroleum hydrocarbons in soil are shown on Figures 6 through 8 These hydrocarbon-affected soils occur in what can be described as two localized verti- cal soil columns Hydrocarbon-impacted soils in these two vertical soil columns occur from a depth of approximately 15 to 50 feet bgs The horizontal extent of hydrocarbon- , affected soils within these soil columns occur pnmanly within a range of 5 to 10 feet, with occasional thin zones that extend horizontally an additional 10 feet from the soil column These soil columns occur within vadose zone soils, soils within the capillary fringe and zone of groundwater fluctuation, and currently saturated soils Figures 6 through 8 depict these conditions and show soil analytical data from soil borings and wells drilled after the operation of the SVE system ' The location of the residual hydrocarbons in soils are charactenzed by soil bonngs , located in two areas These include Soil Bonngs SB-2 and SB-12 located in the north- ern portion of the UST complex and Borings SB-3 and SB-13 located adjacent to the western product island Hydrocarbons in these two areas are well defined and appear to be isolated based on data collected from several borings as shown on the geologic cross- sections (Figures 7 and 8) The concentration of the residual hydrocarbons in soils are characterized by the presence of the relatively high molecular weight compounds TPPH-g concentrations range in i concentration from,less than 10 to 10,000 ppm Benzene with few exceptions has not been detected 3201337B\CLOSLTREI