Human Health Risk Assessment - Raytheon

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4 Human Health Risk Assessment DRAFT Groundwater monitoring at the Facility has shown that COPCs that likely originated from historic manufacturing and storage activities have been detected in groundwater on-Site and beyond the Facility boundaries to the south, east and west. Surface soils in the vicinity of former processing and storage areas have been removed, but associated COPCs remain in groundwater and have been detected in on-Site soil vapor, monitoring wells (on and off-Site) and certain residential irrigation wells. COPCs in soil vapor are capable of entering indoor air environments or being released to outdoor air. COPCs in irrigation water may be brought to the land surface during residential use of groundwater for landscaping and irrigation of homegrown produce. Our evaluation of whether there are potential human health risks from exposures to these COPCs in groundwater, indoor and outdoor air, and homegrown produce is presented in this report. Potential human health and ecological risks are characterized based on COPC concentrations detected in groundwater, soil vapor and on-Site indoor air samples collected during the most recent rounds of monitoring beginning in 2007. These data are presented in detail in the SARA. Population groups (i.e., receptors) used to characterize potential exposures under current scenarios include indoor and outdoor workers at the Facility, construction and utility workers who may be involved in subsurface excavation activities, on-Site trespassers, maintenance/landscape workers on-Site, at the nearby Apartment/Condo Complex and at the public park adjacent to the Site (Azalea Park), ballplayers and visitors to the Azalea Recreation Center, users of the nearby Pinellas Trail and surrounding single and multi-family residents including residents of the Brandywine Apartments and Stone’s Throw Condominiums. 1.1 Overview The Facility is located near the intersection of 22 nd Avenue North and 72 nd Street North in Pinellas County. Three buildings are located on-Site: Building A, Building E and Building M. Dating back to the late 1950’s, the Site has been used for general office use and various electronics manufacturing operations with activities such as soldering, vapor degreasing, painting and electroplating. In 1991, COPCs were first discovered by the County during an environmental site assessment of the then-proposed Pinellas Trail project. The source appeared be located near the northeast corner of Building M. Soils in this area were excavated to the water table to a depth of 1.5 to 2.0 feet below ground surface (bgs) in August, 1992. An additional potential source area, a former wastewater equalization vault located on the east side of Building M, was removed in 1994. Concentrations of chlorinated volatile organic chemicals (CVOCs), a vapor degreasing additive 1,4-dioxane, and miscellaneous other breakdown products and constituents are present in groundwater beneath the Site. The solvents and CVOCs are slightly soluble in water and 1,4-dioxane is miscible in water. These substances can be transported away from source areas by advection and dispersion processes in the general direction of groundwater flow. Recent groundwater monitoring in the area indicates that COPCs in groundwater have been detected off-Site to the east/northeast and to the south and west.
5 Human Health Risk Assessment DRAFT COPCs with sufficient vapor pressure can volatilize from shallow groundwater and diffuse through overlying soils, eventually entering the atmosphere or indoor air. COPCs may also be brought to the land surface via pumping if an irrigation well is installed within the aquifer zone containing COPCs. The Facility is in the process of being vacated as employees move to new facilities in the area. It is anticipated that once the Facility is vacated it will be sold for re-use or redevelopment with appropriate mitigation measures and/or institutional controls. 1.2 Scope of the Risk Assessment The purpose of this report is to evaluate the potential risks from exposure to Site-related constituents under current and likely future exposure conditions in conjunction with the SARA in support of an appropriate remediation plan to be submitted to the Florida Department of Environmental Protection (FDEP). As noted above, this risk assessment addresses Site occupants and visitors, as well as people surrounding the Site, who could be exposed to Siterelated COPCs. This report also includes a qualitative analysis of non-human receptors. To complete this type of an assessment, a series of health-protective assumptions about exposure characteristics must be made. The assumptions used in this assessment have been chosen to be health protective and intentionally conservative and therefore tend to overestimate the calculated non-cancer and theoretical excess cancer risks. For example, maximum concentrations detected in indoor air, soil vapor and groundwater have been used to estimate average potential exposures to the various receptor populations; off-Site residents are assumed to live in the same home for 30 years and spend all their time at home – not accounting for time away at school or at work; and potential non-cancer risks are evaluated separately for a child because potential exposures among children can be greater per unit body weight than potential exposures for adults. Per body weight basis, ingestion and inhalation rates for children yield greater daily exposures than for adults. Children also have a higher surface area to body weight ratios and behave differently than adults. These assumptions tend to overestimate potential risks to receptor populations. The level of exposure estimated in this report is based on extensive sampling data that has been collected to date and is summarized in the SARA which has been submitted to FDEP. The sampling of existing irrigation wells in the off-Site area is currently underway and more data is expected. To expedite evaluation of that data, we have calculated health-based screening levels for constituents in the irrigation water. Comparison of concentrations measured in irrigation wells to the risk-based screening levels will be the first step in identifying any measures (e.g., providing an alternative irrigation water supply) that may be taken to prevent exposure. Also, the numerical values used to represent toxicity are standard regulatory default values intentionally incorporating health protective safety factors. The use of this conservative approach provides a substantial margin of safety to ensure protection for individuals with different potential exposures and sensitivities under actual conditions of exposure.
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7 Uncertainty Analysis 55 Human Hea
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Human Health Risk Assessment 1.0 su
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DRAFT Table 1. Constituents of Pote
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DRAFT Table 3. Comparison Between I
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DRAFT Table 5. Estimated Exposure P
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DRAFT Table 6. Summary of Exposure
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DRAFT Table 8. Source and Derivatio
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Human Health Risk Assessment DRAFT
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DRAFT Primary Primary Secondary Sec
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DRAFT Table A-1. Dose and Risk Calc
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DRAFT CSFd RfDd DA event C w DAD LA
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DRAFT CSFd RfDd DA event C w DAD LA
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DRAFT Table A-13. Dose and Risk Cal
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