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CV. V A S S O C I A T E S I N C In December 1999, ATC personnel supervised the advancement of soil borings MW2, MW3, and �. MW4 at the site to depths of approximately 65 feet bgs to evaluate groundwater for the presence of petroleum hydrocarbons and to determine the gradient direction and magnitude. The borings were completed as monitoring wells. Analytical data indicated that soil samples collected from boring MW2 contained detectable concentrations of petroleum hydrocarbons. Petroleum hydrocarbons were also detected in a groundwater sample collected from well MW2. A groundwater sample collected from MW3 contained very low concentrations of only a few of the requested analytes. Petroleum hydrocarbons were not detected in the groundwater sample collected from MW4. Field activities and analytical results are detailed in ATC's Summary Report rr ofAdditional Subsurface Investigation, dated February 24, 2000. In December 2001, soil-boring VEW1 was advanced to approximately 35 feet bgs, and borings VEW2 and VEW3 were advanced to approximately 45 feet bgs. Borings MW5, MW6, and MW7 were advanced to approximately 65 feet bgs. Soil borings VEW 1, VEW2, and VEW3 were completed as 2-inch diameter vapor extraction wells and soil borings MW5, MW6, and MW7 were completed as 2-inch diameter groundwater monitoring wells. Boring CPT 1 was advanced to approximately 100 feet bgs utilizing a truck-mounted cone penetration test (CPT) rig. A soil vapor extraction pilot test was conducted which yielded a radius of influence (ROI) of tom, approximately 30 feet. Approximately 2.64 pounds of total petroleum hydrocarbons quantified as gasoline (TPHg), benzene, toluene, ethylbenzene, and xylenes (BTEX) were removed during the vapor extraction pilot test. Soil vapor extraction appeared to be a viable method for remediating �.. TPHg and BTEX impacted soil at the site. Field activities and analytical results are detailed in ATC's Remedial InvestigationlFeasibility Study, dated November 19, 2002. �- 2.0 SUBSURFACE CONDITIONS * 2.1 Geolozy rr.. From July 1997 to December 2001, ATC logged a total of five direct push borings (SB-1 through Lo SB-5), ten hollow stem auger borings that were converted to wells (MW-1 through MW-7 and VW1, VW2, and VW3) and one boring utilizing cone penetrometer test methods (CPTI). The subsurface stratigraphy beneath the site is somewhat variable, but generally consists of fine- grained sequence of inorganic clay to silty sand to approximately 10 to 15 feet bgs. Poorly- graded sand with varying amounts of silt was encountered from approximately 10 to 15 feet bgs to 25 to 30 feet bgs and was underlain by a discontinuous heterogeneous mixture of interbedded clay, silt, and silty clay to approximately 40 to 45 feet bgs. A mixture of poorly-graded sand and silty sand was encountered from approximately 40 to 45 feet bgs extending to 65 feet bgs. A line ` of cross-section is shown on Figure 3, and a generalized cross-section is indicated in Figure 4. ry ..0, S:1Envimmnenta11625771SCMCAPAdddoc 2