Society has and will continue to generate hazardous wastes whose risks must be managed. For exceptionally toxic, long-lived, and feared waste, the solution is deep burial, e.g., deep geological disposal at Yucca Mtn. For some waste, recycle or destruction/treatment is possible. The alternative for other wastes is storage at or near the ground level (in someone's back yard); most of these storage sites include a surface barrier (cap) to prevent downward water migration. Some of the hazards will persist indefinitely. As society and regulators have demanded additional proof that caps are robust against more threats and for longer time periods, the caps have become increasingly complex and expensive. We believe it will be possible to develop simpler, longer-lived, less expensive caps that are easier to monitor, manage, and repair. The project is planned to: (1) improve the knowledge of degradation mechanisms in times shorter than service life; (2) improve modeling of barrier degradation dynamics; (3) develop sensor systems to identify early degradation; and (4) provide a better basis for developing and testing of new barrier systems. This project combines selected exploratory studies (benchtop and field scale), coupled effects accelerated aging testing at the intermediate meso-scale, testing of new monitoring concepts, and modeling of dynamic systems. The emphasis on meso-scale (coupled) tests, accelerated effects testing, and dynamic modeling differentiates the project from other efforts, while simultaneously building on that body of knowledge. The performance of evapotranspiration, capillary, and grout-based barriers is being examined. To date, the project can report new approaches to the problem, building new experimental and modeling capabilities, and a few preliminary results.
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