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P A G E 5 • Inhalation of fugitive dust released from exposed soil (non-volatile compounds only). As there are no non-volatile compounds present in soil, this pathway will not be evaluated further. Ground Water For the subject properties, the only realistic ground water exposure pathway involves the inhalation of VOCs' that may be released from the water table into ambient air. Such exposures may occur under current conditions (when the depth to ground water averages 4 to 10 feet below ground surface; ERM, 1999), and during construction activities (when the depth to ground water may be less than 4 feet below ground surface). Other potential exposure pathways related to ground water were not considered to be realistic for these sites, as explained below: • Shallow ground water in the vicinity of the subject properties is not used for water supply. Further, due to the adjacent heavy industrial facilities and the nearby Superfund site, beneath which contaminated ground water persists, it is unlikely that shallow ground water in the vicinity will be used as a water supply in the foreseeable future. Thus, exposures associated with residential and industrial use of ground water are not realistic for the subject properties. • Impacted ground water is confined to a small area in the immediate vicinity for the former USTs. This observation is based upon the eight years of ground water monitoring perfomed at this site. Thus, the migration of ground water to adjacent surface water bodies and the migration of ground water to deeper water-bearing units do not represent realistic exposure pathways for these sites. • The presence of shallow ground water at the site precludes the construction of buildings with basements or other subsurface structures. Thus, the migration of VOCs from ground water into confined spaces does not represent a realistic exposure pathway. ' VOCs detected in ground water include benzene,toluene,ethylbenzene,xylenes, 1,2-DCA,1,3,5-TMB,and 1,2,4-TMB. MTBE is not considered to be volatile (USEPA Region 9,1999). Similarly,TBA is not considered to be volatile,based on its structural similarity to 1-butanol. Note that TBA and 1-butanol have identical chemical formulas and similar chemical properties. The compound 1-butanol is not considered volatile by USEPA Region 9(1999).