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ASS11OVAkTC <br /> OCIATES INC <br /> o Sediments and surface water are not present on site, or in the vicinity of the site, and <br /> therefore, are not considered secondary sources <br /> ' Subsurface soils defined herein as soils at a depth greater than 15 feet b s, are affected primarily <br /> y <br /> at depths above 45 5 feet bgs The results of soil sampling analysis associated with soil bonngs <br /> advanced at the site following the removal of the USTs suggests that the presence of residual soil <br /> contamination can be considered a secondary source of contamination at the site <br /> Based on results of groundwater samples collected from monitoring well MW1 and from soil <br /> probe borings SBI and SB2, a dissolved groundwater plume can also be considered a secondary <br /> source of contamination at the site <br /> In conclusion, based upon site specific conditions, surface soils, free-phase liquids, and sediments <br />' and surface water are not secondary sources at the site Subsurface soils and a dissolved <br /> groundwater plume are the only secondary sources that are present <br /> Transport Mechanisms <br /> The second step in analyzing exposure pathways is to identify possible transport mechanisms <br /> The potential transport mechanisms associated with subsurface soils and a dissolved groundwater <br /> plume are <br /> o volatilization and atmospheric dispersion, <br /> o volatilization and enclosed space accumulation, and <br />' o leaching and groundwater transport <br /> Volatilization and accumulation of residual BTEX constituents and MTBE is a potential transport <br />' mechanism In addition, volatilization from the groundwater and atmospheric dispersion is <br /> considered a transport mechanism The third transport mechanism is leaching from the affected <br /> soil to groundwater and the subsequent transport of the constituents in groundwater All three of <br /> these transport mechanisms are viable at the site <br /> Exposure Pathways <br /> Three complete exposure pathways are possible for the site <br /> ® potable use of groundwater, <br /> ® inhalation of outdoor vapor, and <br /> ® inhalation of indoor vapor <br />' Toi <br /> assess the likelihood that groundwater in the vicinity of the site is being used and/or will be <br /> used for potable water, personnel from ATC performed a groundwater receptor survey for the <br /> subject site as previously discussed Results of this survey indicate that there are up to 33 wells <br /> W 11411851rep,,U\NFA-Reques1 doe 7 <br />