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VA%T <br /> E AS S O G: t -A T E S t N G . <br /> a <br />{ <br /> bsg). TPHg was detected in soil samples at concentrations ranging from nondetect to 5,104 parts ger <br /> million. The extent of TPHg in soil is shown on Figure 5. <br /> 4. 2 Extent of Hydrocarbon-Impacted Groundwater <br /> Based on the analytical results from groundwater samples collected from wells MW-1 through <br /> MW-5, RW-1, VW-4, VW-5s and VW-5d on July 6 1999, and from wells PZ-1, VW-1, VW-2d <br /> and V -3 on November 26, 1997, the lateral extents of groundwater impacted with TPHg, total <br /> petroleum hydrocarbons as diesel (TPHd), and benzene are shown on Figures 6, 7, and 8, <br /> respectively. The highest concentrations of petroleum hydrocarbons are present in wells "4V-1, <br /> VW-1, VW-2 and VW-4. The contamination beneath the site appears to generally be limited to <br /> the vicinity of tanks T-1 through T-4, although:low concentrations of TPHd have been detected in <br /> perimeter wells Nff-3 and MW-5 <br /> I <br /> 5.0 PROPOSED SOIL AND+GROâ–ºUNDWATER REMEDIATION SYSTEMS <br /> The proposed sail and groundwater reined ation systems will consist of combined vapor extraction and j <br />' groundwater air sparge systems. The systems will function as remedial measures for on-site <br /> hydrocarbon impacted.: soil and groundwater. Upon installation and operation of the systems, the <br /> adequacy of the systems to remediate hydrocarbon impacted soil and groundwater to acceptable <br /> regulatory levels for closure will be reassessed. The installation of additional vapor extraction wells or <br /> air sparge wells may be necessary, depending on site-specific conditions. The proposed remediation a <br /> j! <br /> system layout as described in the following paragraphs is shown on Figure 9. P) <br /> i <br /> 51 Soil Remediation System <br /> 5.1.1 Vapor Extraction System. <br /> The proposed vapor extraction system('VES)will utilize existing vapor extraction wells BIW-1,VW-3, <br /> and VW-5s, a vacuum blower, and an off-gas abatement system to address the hydrocarbon impacted <br /> soil. Due to the increase in the water table elevation over the course of the investigations, the three <br /> remaining vapor wells are screened below,the water table and are unusable. An estimated three <br /> W:\6-2574.01\CAP report dor 8 <br />