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2.2 Nature and Extent of Soil and Sediment Contamination The Site 47 RUFFS combined the analytical data and other information collected between 1995 and 2020, presented the analytical data on contaminant specific figures, and evaluated the risk to human health and the environment for contaminants in soil and sediment. The Site 47 RUFFS also evaluated remedial alternatives, as discussed elsewhere in this Site 47 RAP. The remedial investigations were conducted to identify and characterize contamination present due to historical operations. Table 1 provides a summary of the information contained in the major technical reports prepared by contractors for the Navy and the Port. Between 1995 and 2020, hundreds of soil samples were collected from Site 47 and the adjacent areas and analyzed for chemical constituents, including metals, polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs),polycyclic aromatic hydrocarbons (PAHs), semi- volatile organic compounds (SVOCs), volatile organic compounds (VOCs), and total petroleum hydrocarbons (TPH). Sediment samples were also collected from the drainage channel along the southern boundary of Site 47, and analyzed for metals, PCBs, OCPs, PAHs, SVOCs, VOCs, and TPH. Depths of samples varied from the top 6 inches to 22 feet bgs. Contaminants detected in soil include metals (primarily arsenic), PAHs, and OCPs. Figure 5 presents the data set boundary that encompasses the soil sample locations, along with sediment and groundwater sample locations, within and adjacent to the Site 47 boundary. Analytical data for soil samples are presented in Tables 2 and 3, and Figures 6 through 8. Soil data from the skeet/trap shooting range was evaluated independently to better assess the contaminant distribution(primarily lead and PAHs) associated with firing operations. Contaminants detected in sediment include metals (primarily arsenic and nickel), PCBs, and OCPs. Analytical data for sediment samples are summarized in Table 4, and sediment sample locations are shown on Figure 9. 2.3 Nature and Extent of Groundwater Contamination Groundwater investigations at Site 47 have focused on metals, specifically arsenic. In 2015, the Port evaluated elevated arsenic concentrations in shallow groundwater. Arsenic concentrations above acceptable drinking water standards have been detected in most of RRI's monitoring wells. The 2015 evaluation concluded that natural processes, including biogeochemical processes occurring due to RRI's location within the Delta, were responsible for the elevated arsenic concentrations in groundwater at RRI (Environmental Risk Services [ERS], 2015b). The CVRWQCB and DTSC have agreed with the conclusion that arsenic is naturally occurring at RRI, indicating that observed arsenic in RRI groundwater, including at Site 47, reflects background concentrations (CVRWQCB, 2016). The Port is planning to conduct a site-wide analysis of background concentrations of additional metals in groundwater at RRI. Previous groundwater investigations did not identify significant occurrence of organic chemicals at Site 47. The DTSC and CVRWQCB requested additional data to support a groundwater monitoring program, which would evaluate the potential risks to humans and wildlife and determine the potential need for remedial action in groundwater. Figure 4 shows existing monitoring wells at Site 47 RAP for Soil 7 October 2023