Results of annual comprehensive sampling of the F- and H-Area seeplines along Fourmile Branch: April 1998

In April 1998 water samples were collected from Fourmile Branch (FMB) and its seeplines in the vicinity of the F- and H-Area Seepage basins. This annual sampling event is a continuation of previous sampling events. The objective of this study is to characterize the shallow groundwater outcropping into FMB and its wetlands. In the past, this groundwater has been shown to contain contaminants migrating from the F- and H-Area Seepage basins. The samples were analyzed for Resource Conservation and Recovery Act (RCRA) Appendix IX metals, selected radionuclides, and selected inorganic constituents. Analyses of volatile organic compounds were discontinued in 1996 because concentrations were below the method detection limit or insignificant. Results from this sampling event indicate that the seeplines of F and H Areas and FMB continue to be influenced by contaminants in groundwater originating from the capped seepage basins, but to a lesser degree than in the past. This suggests that the most concentrated portion of the contaminant plume may have dissipated. Contaminant concentrations measured during this sampling event were compared to primary drinking water standards (PDWS), secondary drinking water standards (SDWS), and maximum contaminant levels (MCL) enforceable in 1998. Results were also compared to the 1989 baseline measurements at corresponding locations