Long-Term Verification of Cover Systems Using Perfluorocarbon Tracers

The expanded use of caps and cover systems is an important aspect of the U.S. Department of Energy Environmental Managementʹs strategy for restoration and long-term stewardship of sites throughout the complex. However, very little is available in terms of long-term monitoring of covers other than downstream groundwater or surface water monitoring. A novel methodology for verifying and monitoring subsurface barriers and cover systems has been developed. Gaseous perfluorocarbon tracers (PFTs) are injected on one side of the barrier and searched for on the opposite side of the barrier. The capability for leak detection in subsurface barriers using PFTs has been proven at multiple demonstrations. Adaptation of this concept to covers is a necessary step prior to full-scale demonstration. This paper discusses the PFT technology and a successful proof-of-principle test of the PFT technology as a leak detection tool for cover verification and monitoring.