COMPACTED SOIL BARRIERS AT ABANDONED LANDFILL SITES ARE LIKELY TO FAIL IN THE LONG-TERM

At innumerable sites in the USA and around the world, buried waste has been isolated from the environment by barriers constructed entirely o r in part of compacted soil. The chief concern in barrier design has b een to isolate the waste in the short term by preventing movement of w ater into and through the waste. However, in the long term a variety o f mechanisms can act to compromise this isolation. The mechanisms of l ong-term failure include initial flaws in barrier construction, shrink -swell cycles, freeze-thaw cycles, erosion, subsidence, root intrusion , and animal intrusion. Evidence for action of all of these mechanisms is summarized. The likelihood of long-term failure suggests that eith er perpetual care must be provided for buried hazardous wastes, or the waste sites must be designed to withstand long-term threats to barrie r integrity.