The primary objective of this project is to develop and demonstrate a close-coupled barrier for the containment of subsurface waste or contaminant migration. A close-coupled barrier is produced by first installing a conventional cement grout curtain followed by a thin lining of a polymer grout. The resultant barrier is a cement-polymer composite that has economic benefits derived from the cement and performance benefits from the durable and resistant polymer layer.

A full-scale Close-Coupled Barrier was installed at Brookhaven National Laboratory's Glass Holes Waste Site. The barrier was a V-trough consisting of a cement outer layer and an acrylic inner layer that adds additional containment capabilities in terms of chemical resistance and permeability reduction. Some Photos and Video Clips are available of the site and the grouting process. The Final Summary Report has been issued [BNL-52531].

The Environmental and Waste Technology Center at BNL has played a key role in the barrier development effort. BNL has investigated the regulatory issues, assumptions and drivers associated with the use of barriers and advanced polymer systems. BNL, with funding from the DOE Office of Science and Technology, has developed advanced polymer barrier materials and investigated their durability and performance characteristics under typical waste site conditions.

The objective of this task was to develop, demonstrate and implement advanced subsurface barrier materials for USTs. The materials were selected based on their applicability with conventional placement technologies, low permeability to water, resistance to aggressive chemicals, radiation resistance and tolerance to an elevated temperature environment.