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Sent By,: BASELINE; 510 420 1707; Nov-9-99 15:31 ; Page 23129 <br /> i <br /> HUMAN HEALTH SCREENING EVALUATION <br /> A human health screening evaluation was conducted for the site in accordance with the PEA <br /> Guidance Manual (DTSC, 1994). This screening evaluation uses generic assumptions,models,and' <br /> parameters to estimate a conservative preliminary risk and hazard for a predetermined set of <br /> exposure pathways in an assumed residential setting. The resulting risks and hazards provide DTSC <br /> with comparability between sites through the uniform application of their guidance but does not <br /> represent true risks or hazards. This site is not currently, has not in the past, and will not in the <br /> future under the proposed redevelopment be a residential land use. Alternative land use scenarios <br /> are beyond the scope of the human health screening, as part of the PEA process. <br /> EXPOSURE PATHWAYS AND MEDIA OF CONCERN <br /> k Current Cunditions <br /> Under current site conditions, potential direct contact of human receptors to contaminants in soil, <br /> groundwater, sediment, and surface water is limited and represents incomplete pathways. The site <br /> is entirely capped and fenced, preventing entry to the site, and shallow groundwater is not used as <br /> I�I a drinking water source at the site. Potential direct contact with surface water underneath the site <br /> I is pussibiv via boat through a small opening under the Center Street Bridge; however, this also <br /> represents an incomplete exposure pathway since swimming is prohibited in this area, and boating <br /> or fishing,even if conducted underneath the parking structure,would not result:in significant surface <br /> water contact. Residual concentrations of volatile organics,which could volatilize into ambient air <br /> through cracks in the pavement, are present in soil and groundwater underlying the site;'although <br /> i the paving would prevent volatilization to a large extent and the site is fenced as "no trespassing." <br /> Exposure to particulates and volatile organic compounds in air is therefore assumed to be an <br /> incomplete pathway. Volatilization of volatile organics into indoor spaces is not considered a <br /> complete exposure pathway since no buildings are located on-site. <br /> Proposed Future Conditions <br /> Under proposed future site conditions with redevelopment of the site as a water square,direct contact <br /> of human receptors to surface soil would be limited to those areas that are not paved;however,these <br /> areas would be landscaped and would act to prevent contact with soil at the site. It is anticipated that <br /> in areas of landscaping,sail would be imported to support landwape growth or planter boxes would <br /> be used. Potential contact with shallow groundwater, surface water, and sediment would not <br /> represent complete exposure pathways under the proposed redevelopment of the site. Swimming <br /> would continue to he prevented at this location, entry to the Stockton Channel would be prevented <br /> by railings,and the seawalls.would prevent contact with sediments. Fishing and boating would not <br /> be permitted within the water square, and would be preventrxl by the seawall; fishing and boating <br /> would,however,continue to occur off-site west of the seawall. Drinking water and irrigation water <br /> would be provided by the City of Stockton's potable water system. <br /> J Although drinking water would be provided by a source outside the project area., ingestion and <br /> showering of shallow Vrundwater underlying the site was evaluated as a complete,exposure <br /> pathway in the PEA, as requested by DTSC personnel. This is considered a very conservative <br /> assumption since the groundwater well survey indicated that the shallowest depth at which <br /> k 97369stkpe�,wp1 I k/D�49 17 <br /> i <br />