Covering It All

When designing covers for contaminated soils, engineers generally follow the procedures outlined by the US Environmental Protection Agency (EPA) and rely on such guidelines as the EPA's 1991 report Design and Construction of Resource Conservation and Recovery Act/Comprehensive Environmental Response, Compensation and Liability Act Final Covers. The prescriptive design called for in that publication relies on the use of such materials as geomembranes when designing a cover that comes into intimate contact with compacted clay that has a low saturated hydraulic conductivity. Both engineering and institutional controls were established to protect the integrity of the covers and, as a result, aid in ensuring the long-term protection of human health and the environment from the waste contained beneath the covers. The engineering controls include obelisks, a fence, warning signs, and survey monuments at the perimeter of the waste containment area that clearly demarcate the region as well as the cover boundaries.