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<br />Page 2 <br />Proposal for Risk Assessment <br /> <br />707 Bradford, Redwood City, CA. <br /> <br />resident in a managed care facility. Potentially complete exposure pathways for risk <br />evaluation under the day care scenario include direct contact with chemicals in soil via <br />ingestion, dermal exposure, and inhalation of chemicals adhered to dusts. For the elderly <br />resident in a managed care facility, complete exposure pathways are limited to inhalation <br />of dusts. Direct soil exposure is not anticipated for elderly people in a managed care <br />environment. <br /> <br />Note that the day care exposure scenario is less conservative than a residential scenario, <br />since it does not assume the children live onsite. However, this will address the question <br />from a site-specific development viewpoint. The elderly residents would be assumed to <br />live onsite, but not for a 30-year period due to their advance age. <br /> <br />Groundwater will also be included in the SCM, focusing on the level of protection to <br />human and ecological health afforded by a detection limit of 2 ug/L for some of the <br />P AHs. This includes evaluation of the domestic use of groundwater scenario for human <br />health, as well as consideration of aquatic ecological receptors in the nearby Creek. No <br />other evaluation of groundwater data will be conducted in this focused risk assessment. <br /> <br />Task 2. Risk Evaluation. <br />This task includes what is essentially a targeted, Tier 2 risk assessment under RWQCB <br />guidance. As such, the following Scope of Work will be conducted. <br /> <br />Data Evaluation. <br /> <br />In soil, Chemicals of potential concern (COPCs) have already been identified by the <br />SCHMSA, and include the following P AHs: <br /> <br />. Naphthalene <br />. Chrysene <br />. Benzo(b )fluoranthene <br />. Benzo(k)fluoranthene <br />. Benzo( a )pyrene <br />. Benzo(g,h,i)perylene <br />. lndeno( 1 ,2,3-c,d)pyrene. <br /> <br />These COPCs have concentrations exceeding Environmental Screening Levels (ESLs; <br />RWQCB, 2005). Potential cancer risks and non-cancer hazard quotients will be <br />estimated for the COPCs in the Tier II assessment. The Tier II assessment includes the <br />typical components of a risk assessment (i.e., data evaluation, exposure assessment, <br />toxicity assessment, and risk characterization). <br /> <br />Concentrations of the COPCs "vill be statistically evaluated for areas no larger than a <br />standard residential lot (1000 ft2J, consistent with DTSC guidance. <br /> <br />In groundwater, the analytical detection limit of 2 ppb for P AHs will be considered as a <br />single concentration for further evaluation. <br />