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Mr Ronald Rowe <br /> C A M B R I A August 26, 1999 <br /> 1989 to 1992 Well Installation: Between May 1989 and April 1992, twenty soil borings were <br /> drilled, eleven groundwater monitoring wells were installed (MW-1 through MW-11), and four <br /> nested soil vapor extraction (SVE) wells (VEW-1 through VEW-4)were installed at the site Soil <br /> analytic data is summarized in Attachment A <br /> June 1992 SVE Test: A SVE test was conducted in June 1992 using the four nested SVE wells <br /> The test indicated that the wells would have a radius of influence of about 25 feet at about 25 <br /> cubic feet per minute (cfm) TPHg concentrations in the vapor stream ranged from 3,300 to <br /> 30,000 milligrams per cubic meter <br /> September 1993 Well Installation: In September 1993, wells MW-13 through MW-17 were <br /> -r <br /> drilled off-site to further define the extent of hydrocarbons in soil and groundwater Based on <br /> the investigation results, it was estimated that about 5,600 pounds (896 gallons) of TPHg were in <br /> the subsurface <br /> Sod Vapor Extraction System Installation: A SVE system consisting of a thermal oxidizer <br /> connected to the four SVE wells was started on August 28, 1995 The initial TPHg removal rate <br /> was 85 pounds per day (ppd) Between January 1996 and March 1998, the SVE system removed <br /> approximately 6,256 pounds of hydrocarbons The system was shut down on March 9, 1998 due <br /> to low hydrocarbon removal rates and a rising water table The SVE performance data are <br /> presented in Attachment B <br /> Current Site Work: The four fuel USTs were removed during July 1999 The fuel dispenser <br /> islands and the associated piping were also removed Cambria collected soil samples from <br /> beneath the USTs, dispenser islands, and piping We also performed over-excavation work <br /> during August 1999 Once we have received all of the soil analytical results we will prepare a <br /> report documenting the UST removal and soil sampling activities <br /> HYDROGEOLOGY <br /> Soils encountered beneath the site consisted of interbedded clay, silt and sand A bluish-gray <br /> clay was encountered at depths between 39 and 42 feet depth During drilling in 1993, <br /> groundwater was initially encountered in the semi-confined clayey, silty sand units below the <br /> bluish-gray clay Cross-sections prepared by previous consultants are included in Attachment C <br /> 2 <br />