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' 15 June 1999 AGE-NC Project No 98-0450 Page 10 of 27 ' 4 2 4 Feasibility and Soil Vapor Extraction Pilot Test As outlined in the guidance document,How to Evaluate Alternative Cleanup Technologies Fol UST ' Sites (USEPA, 1994), the two most important factors that determine the effectiveness of SVE are Permeability of the soil and volatility of the contaminant Coarse-grained soil (sands) have greater intrinsic permeability than fine-grained soil (clays or silts) The guide states that intrinsic permeability ranging in magnitude from 10 2 cm2 to 10 s cm2 (sand to silty sand), as well as the volatility of gasoline- and lighter diesel-range hydrocarbons are conducive parameters for remediation by SVE technology SVE generally is less effective for silty sand to silt soils with ' intrinsic permeability ranging from 101 cm2 to 1010 cm2 Soil with intrinsic permeability less than 1010 cm2 (silty clay to clay) are marginally effective to ineffective for SVE technology ' Soil Vapor Extraction Feasibility Testing ' A vapor extraction feasibility test was performed at the site On 12 May 1999, an 8-hour soil vapor extraction (SVE) test was initiated at the site This pilot test was performed to provide SVE data prior to initiation of a full scale remediation system The test was conducted using a VACLEEN M 1000 SVE system, manufactured by Environmental Techniques The VACLEEN unit consists of a positive-displacement blower, driven by an internal combustion (1C) engine Propane was used as a supplemental fuel source to start the engine and maintain performance Hydrocarbon vapor was destroyed as part of the internal combustion process Emissions from the engine were routed through two catalytic converters to maximize the destruction rate of the extracted hydrocarbon vapors ' Procedures The test was initiated at 8 00 am and continued for appioximately 8 hours An induced vacuum potential was applied to the casing of vapor well VW-2 for approximately eight hours ' The vacuum-induced pressure reduction was monitored at surrounding observation points (BMW-1, BMW-2, BMW-3, BMW-4, BMW-5 and MW-5 and vapor well VW-1) with air tight well caps pre- connected with Magnehelic vacuum gauges fitted to each observation well A sample port was tapped into the PVC near the wellhead and a portable organic vapor meter equipped with a photo- ionization detector (PID Thermo model 580A calibrated to isobutylene 100 ppm) was used to ' measuie organic vapor(OV) concentiations The organic vapor concentrations, the induced vacuum potential at the observation points, extracted soil gas flow rate, and RPMs of the SVE unit were measured at 0 5-hour or 1 0-hour intervals and logged on field sheets Pilot test data are summarized ' in Table 5 SampluiR and Analyses A total of four soil vapor samples were collected during the pilot test Soil ' vapor samples were collected at two-hour intervals from the inlet of the extraction well to measure hydrocarbon concentrations in extracted vapor The samples were collected in Tedlar bags using ' an air pump Samples were transported in a chilled container under chain-of-custody to Mc Campbell Adranced GeoEm IronmentaI,Inc I 1 I Ip