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Final Release LLNL Site 300 (USDOE) remediation thus far, its aggressive treatment strategy for the future, and the continued monitoring of site contaminant plumes, ATSDR scientists have concluded that exposure to Site 300 contaminants in the future is unlikely. Using current data, and provided that no new contaminant source develops and migrates off-site,potential residential developments near Site 300 will be unaffected by contamination originating at Site 300. The Pit 6 landfill was capped in 1997 to prevent rainwater from infiltrating the landfill and leaching additional contaminants into the groundwater. Contaminated groundwater plumes from the Pit 6 OU are not predicted to migrate off-site (LLNL 2000). ATSDR scientists have concluded that in the future, residents of the CSVRA will not be exposed to contamination from the Pit 6 landfill. Soil and Sediment Background LLNL has been monitoring surface soil near LLNL Site 300 since 1971. Soil sampling is conducted at 14 locations at Site 300 as part of a continuing LLNL monitoring program designed to measure any changes in environmental levels of radioactivity (LLNL 2001). Each of these locations is situated near firing tables and other areas of potential soil contamination. Soil samples were analyzed for gamma-emitting radiation and for beryllium. Plutonium analysis was discontinued for soil samples from Site 300 because since sampling began, plutonium levels have consistently been at background levels (i.e.,levels expected from global fallout) (LLNL 2001). Soil and sediment samples are also collected and analyzed for VOCs, HE compounds,uranium, PCBs, metals, tritium,perchlorate, general minerals and nutrients as part of the CERCLA investigations. There are no perennial streams at or near Site 300; therefore, no sediment sampling locations have been established. Overland flow occurs intermittently and often at relatively high flow rates, as in a storm; therefore sediment does not accumulate. For this reason,LLNL deemed sediment sampling at Site 300 unwarranted. Contaminants of Concern Although soil contamination exists on Site 300, particularly around the firing tables in the EFA/WFA and from surface spills throughout the site (see Table 3), there has been no evidence of off-site contaminated soil. Because access to Site 300 is limited, there is no exposure of the public to contaminated soil from Site 300. There are no contaminants of concern in the off-site soil and sediment. Surface Water Background As stated, no perennial streams exist on or near Site 300. After heavy rains, surface runoff occurs through ravines,primarily Elk Ravine, and intermittent stream channels. Runoff that does not infiltrate the ground eventually discharges into Corral Hollow Creek. Corral Hollow Creek is an 17