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Review of the cancer risk results summarized in Table 6-1 shows that the estimated cumulative cancer risk for all receptors did not exceed the EPA target risk range. Review of the cancer risk estimates for current and future occupational employees were significantly below the EPA target risk range. The risk for the occupational RME scenario was 1.0E-10 and 1.1E-11 for the average scenario. The pathway with the highest risk was ingestion of drinking water. The pathway with the lowest carcinogenic risk was inhalation of soil emissions. Table 6-3 is a summary of the risks for RME occupational employees showing all pathways and chemicals. Table 6-4 is a summary of the risks for the average occupational employees. The highest estimated cancer risk was for the hypothetical adult residential RME scenario of 1.1E-07. The chemical of concern that made up the carcinogenic risk numbers was benzene, the only carcinogen for the site. The average adult residential — scenario was 6.7E-09. The pathway with the largest risk was inhalation during showering followed by ingestion of drinking water. Table 6-5 is a summary of the risks for RME hypothetical adult residents and Table 6-6 presents the risks for average adult residents. Cancer risk results for hypothetical child residents were significantly below the EPA target risk range at 4.1E-08 under the RME scenario (Table 6-7) and 1.3E-08 under the average scenario (Table 6-8). Using the seasonal high groundwater depth of 65 feet bgs, the cancer risk number was 4.8E-08 (Table 6-9). The pathway with the largest risk using the high groundwater depth and RME child resident scenario was ingestion of drinking water at 3.1E-08. In summary,inspection of Table 6-1 shows that hypothetical consumption of groundwater comprises the chief risk at the site (4.9E-08 for RME adult residential). The numbers are significantly below the target risk range. The numbers were calculated using worse- case assumptions which would increase the possible groundwater concentrations (i.e., no biodegradation,highest detected concentration,high infiltration in soil,high permeability — in groundwater, etc.). In addition, the source of the chemicals are gone (tanks have been removed) and the chemicals have not been detected in groundwater near the `r former tank site or at the well. S:\LDC\YELLO.Rn May 4,1995 6-7