Asphalt barriers for waste isolation

Prior to the mid 1980s, asphalt barriers were primarily used to control water seepage from facilities such as ponds, impoundments and earth dams. Asphalt was applied as hot-sprayed buried asphalt membranes and as asphalt concrete for the barrier layers. The establishment of rules for hazardous and solid waste landfill designs focused the industry toward composite liners consisting of geomembranes and compacted soil. However, in the mid-1980s, resurgence into the use of asphalt concrete for waste isolation was initiated by the US Department of Energy in their quest for very-long-term (1000+ years) hydraulic barriers for radioactive and mixed waste sites. Existing data demonstrate that asphalt concrete barriers and fluid-applied asphalt layers can provide extremely low hydraulic conductivities (<1x10-11 cm/s). On-going research results show that asphalt may have the robust properties for a service life approaching 1000 years. Field demonstration of the attributes of asphalt concrete barriers through test pads and monitored prototypes can answer the question of equivalency or superiority of asphalt concrete barriers for waste isolation.