Following up on OST technologies
The December 1995 Initiatives carried an article on Sandia National Laboratories' five-year project to demonstrate several alternative approaches to covering hazardous waste landfill sites. Resource Conservation and Recovery Act guidelines require hazardous waste landfills be capped by barrier layers that block infiltration of water through the cover into the waste. RCRA stipulates a two-foot clay layer, which is not readily available at many Western landfill sites. In Phase II of the project, Sandia is evaluating several innovative cover designs as alternatives to a RCRA-approved liner. Through the demonstration project, the U.S. Department of Energy is trying to gain regulatory approval for use of alternative cover designs that perform as well and are less costly to construct than RCRA covers.
In early September, the state of New Mexico and the U.S. Environmental Protection Agency approved the demonstration of an innovative landfill cover design at a Bureau of Land Management Superfund site. If proven effective, the cover could significantly reduce remediation costs at Western DOE and U.S. Department of Defense sites. The $3.5 million project at BLM's Lee Acres Landfill Site involves a low-permeability soil cap specially designed for arid climates by Sandia National Laboratories.
The unique cover offers significant cost savings over conventional RCRA soil caps by trapping water in capillary pore spaces and using it as an infiltration barrier, thereby causing water to drain laterally, not downward. BLM has proposed deploying the cap on approximately 20 acres of the closed landfill, pending the successful completion of a one-acre pilot project. BLM recommends natural attenuation as long as the manganese-contaminated plume does not appear to migrate. EPA is currently drafting a Federal Facilities agreement with BLM and the U.S. Department of the Interior, which along with the final Record of Decision was expected to be signed by November. Public comment on the proposed cleanup plan ran through October 16.
