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F. Amador <br /> March 1, 1993 <br /> Page 3 <br /> 5. Page 7-31, Sec. 7 .4 Exposure Assessment. The baseline risk <br /> assessment should reflect current conditions at the <br /> facility. Therefore, the identification of potential <br /> exposure pathways and populations must be based on the <br /> assumption that no site remediation has taken place. Thus, <br /> exposure routes and/or receptors should not be eliminated <br /> (as they were in Table 7-8) just because the site is <br /> presently covered or a deed restriction has been proposed. <br /> 6. Page 7-34 . Lacking compelling arguments to the contrary, <br /> future residential land use of Areas I and !I should be <br /> assumed. This provides a scientific basis to support <br /> stipulations in the deed restriction. <br /> 7 . Page 7-34 to 7-44 & Table 7-8 . <br /> a. Future workers. The health risk to future yard workers <br /> is not considered. -Instead, it is assumed that the <br /> future owners will be notified in the deed restriction <br /> that protective measures need to be taken. This would <br /> seem to place the responsibility on the future owner to <br /> conduct a risk assessment to ascertain what protective <br /> measures must be taken, considering future land use and <br /> worker activity patterns. <br /> It cannot be assumed that future yard workers will have <br /> activity patterns similar to those of current workers, <br /> and that future occupational exposures will be similar <br /> to current exposures. Even a relatively small change <br /> in activity patterns could result in a significant <br /> change in risk. For example, current workers are only <br /> exposed to Area II for 3 days per year. However, even <br /> this limited exposure results in a 3 x 10,6 excess <br /> lifetime cancer risk to workers (see Tables 7-12 and 7- <br /> 14) . <br /> Table 7-8 indicates that exposure to vapors in the <br /> subsurface soils of Area I will not occur because <br /> " . .the presence of COPC (chemicals of potential <br /> concern] by the deed and SARA Title III notification <br /> requirements prevent future unprotected exposure. " <br /> Legal notification requirements do not prevent <br /> potential future exposures. <br /> b. Current Workers. Potential exposure of current on-site <br /> office workers to subsurface soil vapors is also <br /> eliminated based on the reasoning that there is no <br /> known contaminant source under the building, and COPC <br />