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ously petroleum-impacted soil on the site TRH and particularly benzene concentrations in <br /> . groundwater increased Groundwater flow direction was consistently toward the north- <br /> east at slopes ranging from approximately 0 59% to 0 80%, or 31 to 42 feet per mile, <br /> respectively <br /> Sampling of the five on-site monitoring wells next occurred in December 1994 Water <br /> levels were observed to be approximately 26 to 26 5 feet bgs, or a rise of roughly 2 to <br /> 3 inches compared to measurements obtained in December 1993 Again, because this <br /> water level rise resaturated soils previously impacted by petroleum hydrocarbons, petro- <br /> leum constituent concentrations in groundwater samples increased Groundwater flow <br /> remained in a northeasterly direction <br /> In October 1993, an evaluation of remedial alternatives for petroleum-impacted soil was <br /> performed The purpose of this investigation was to assess the feasibility of a soil vapor <br /> extraction and treatment system The scope included eight additional soil borings and one <br /> pilot soil vapor extraction well The results of the soil sampling showed detectable <br /> concentrations of petroleum hydrocarbons in the soil at a depth of 23 to 28 feet bgs <br /> across the site The report also concluded that sal vapor extraction was a feasible <br /> remediation alternative <br /> 3. FIELD ACTIVITIES <br /> Collection of Soil Vapor and Soil Samples <br /> On 27 February 1995, soil vapor samples were collected from three sampling locations <br /> (SV1 , SV2, and SV3) at depths of 16, 21 , and 24 feet bgs Samples were collected by <br /> simultaneously driving a 23/8-inch diameter drive casing and a 15/8-inch diameter soil core <br /> tube into the soil The soil core tube was removed after every 3-foot advance to observe <br /> and identify lithologic conditions and monitor potential organic vapors from the sample <br /> using an HNu portable field meter (see Section 4 Site Lithology) As the drive casing <br /> reached desired sampling depths, a discrete soil sample was collected, and the soil core <br /> • <br /> q'oka5940549Veaar2 doe <br /> 3 940549 00 <br />