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� v <br /> ATC <br /> A S S O C I A T E S I N C <br /> bsg) TPHg was detected in soil samples at concentrations ranging from nondetect to 5,100 parts per <br />' million The extent of TPHg in soil is shown on Figure 5 <br /> 4_2 Extent of HaLc[rocarbonjmipacted 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 VW-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 lughest concentrations of petroleum hydrocarbons are present in wells MW-1, <br /> 1 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 T4, although low concentrations of TPHd have been detected in <br /> perimeter wells MW-3 and MW-5 <br /> M5.0 PROPOSED SOIL AND GROUNDWATER REMEDIATION SYSTEMS <br /> The proposed soil and groundwater remedsation systems will consist of combined vapor extraction and <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 <br /> system layout as described in the following paragraphs is shown on Figure 9 <br />' 5_1 Soil Remediation System <br /> 5.1.1 Vapor Extraction System <br />' The proposed vapor extraction system(VES)will utilize existing vapor extraction wells VW 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 162574 WCAP report doc 8 <br />