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2. NATURE AND EXTENT OF CONTAMINATION Between 1995 and 2020, the Navy and the Port conducted remedial investigations at and adjacent to Site 47 to assess the nature and extent of contamination in soil, sediment, and groundwater. The following sections briefly discuss the conceptual site model and the nature and extent of contamination in Site 47. Additional information is provided in the Site 47 RUFFS. 2.1 Conceptual Site Model Soil and sediment contamination within Site 47 resulted from spills and releases from historical site operations which, as described Section 1.3, consisted primarily of recreational use (i.e., model airplane landing strip and skeet/trap shooting range). Figure 10a(Conceptual Site Model - Human Health Risk Assessment) and Figure 1 Ob (Conceptual Site Model - Ecological Risk Assessment)provide graphic representations of the path that contamination takes from the release locations to people (workers or possible residents) or ecological receptors (plants and animals). The Site 47 RUFFS evaluated the risks for the following exposure pathways, as summarized in the following paragraphs. In the absence of any remediation or mitigation efforts, a future worker could potentially be exposed to contaminants of concern(COCs) in soil through incidental ingestion of soil, dermal contact with soil, and inhalation of particulates or volatiles in ambient air. The risk for a hypothetical future resident was also evaluated to provide information to support risk management decisions (i.e., determine the need for institutional controls). Wildlife may be exposed to the contaminated soil and sediment through the following pathways: • Direct exposure (dermal contact/ingestion) to soil and sediment contaminants of ecological concern (COECs)by plants, soil-dwelling-organisms, birds, and mammals; and • Indirect exposure to soil and sediment COECs through bioaccumulation into other organisms and their consumption by birds and mammals. The risks from these exposure pathways were evaluated in the Site 47 RUFFS and are summarized in Section 3.1. While Figures I Oa and 1 Ob indicate potentially complete exposure pathways for groundwater and surface water(within drainage channels), the Site 47 RUFFS did not evaluate risks from chemicals in groundwater and surface water. As described in Section 1.1, groundwater conditions are influenced by naturally occurring arsenic, but the Port is currently conducting an island-wide assessment of background concentrations of additional metals in groundwater at RRI. Site 47 groundwater conditions will be re-evaluated once the island-wide assessment is completed. Site 47 RAP for Soil 6 October 2023