The tanks and the highly radioactive waste in them are the biggest environmental threat at the site. See: “TECHNICAL REVIEW OF ENVIRONMENTAL MONITORING REPORTS FOR F-AREA [FTF] AND H-AREA TANK FARM [HTF] FACILITIES”
Overview of conclusions from the NRC:
“DOE has performed environmental monitoring that provides useful information on the hydrogeological systems at FTF and HTF.”
“Uncertainty exists in the source of contaminant plumes detected via the FTF and HTF monitoring well networks. A better understanding of contaminant flow and transport processes at the TFFs, and more extensive data analysis and interpretation could help reduce this uncertainty.”
“Performance assessment modeling and analysis should be better integrated with the groundwater monitoring program at the TFFs. For example, FTF and HTF monitoring well placement could be better optimized to detect releases from the tank farm facilities should releases occur in the future.”