SITE INFORMATION AND CORRESPONDENCE

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Ly araat�aNt; 510 420 1707; Nov-9-99 17:02; Pae 3,13 The excess lifetime cancer risk fmm exposure to volatile organics frarn soil and groundwater in indoor air was 4.7 x 10-8, and the hazard was 0,0013. Both are below the thresholds considered by DTSC as potentially significant. The cumulative excess lifetime cancer risk and hazard from soil ingestion and dermal contact, groundwater ingestion and showering/bathing with shallow groundwater underlying the site,ambient air, and indoor air were calculated to be 3.3 x I0-4, and 0.67, respectively. if the maximum concentration of COPCs in groundwater, as reported in the off-site wells/hydropunch borings immediately upgradient of the Weber Block property were included in the risk and hazard calculations, the cumulative cancer risk and hazard from soil ingestion and dermal contact, groundwater ingestion and showering/bathing (off-site groundwater), ambient air, and indoor air were calculated as 2.4 x 10.3 and 150, respectively. The cumulative excess lifetime cancer risks des ribed above both exceed the DTSC threshold; the hazard index threshold was only exceeded assuming use of groundwater from off-site wells/hydropunch boring locations immediately upgradient of the Weber Block property. The risk and hazard for each COPCs for each exposure pathway and for exposure pathways combined are provided in Appendix C. Results for Lead The 99th percentile blood lead concentrations calculated were 2.4 µg lead/dl blood for adults, and 6.5 µg lead/dl blood for children. These calculated blood lead Ievels are below the level of concern of 10 pg lead/dI blood established for the 99th percentile exposed receptor by DTSC. The largest contribution to blood lead concentrations was from ingestion of store bought food(85 percent for adults and 72 percent for children) (Appendix D). ECOLOGICAL SCREENING EVALUATION SITE CHARACTERIZATION The same contaminants as those described under the human health screening evaluation may potentially impact ecological health,if exposures occur. In addition to the COPC5 identified under the Human Health Screening Evaluation, metals present at the site may have adverse effects on aquatic organisms at concentrations lower than wouldbe of concern for humans,if exposures occur. The maximum concentration of these contaminants in soil and groundwater are presented in Tables 7A and 7B above. BIOLOGICAL CHARACTERIZATION Aquatic The Amended West End ETR prepared in 1941 described the biological characterization of the Stockton Channel area(Paoli and Associates, 1991). Additional information has become available for the sheet wall design construction for the Weber Block Redevelopment Project and additional fish species have been listed under the Federal and State Endangerod Species Act since 1941. information in the Amended West End EiR was therefore supplemented by information in the Weber 97369fA.peA.wpd-1 119199 25