Mechanical and Civil Engineering Seminar

This presentation discusses the recent design, construction and monitoring of the unsaturated soil covers of a high-visibility hazardous waste facility: The Rocky Mountain Arsenal (RMA). Located near Denver, Colorado, the RMA site was once considered to contain the most contaminated square mile on earth. Unsaturated soil covers were adopted for final closure after establishing and following an equivalence demonstration process that involved a field monitoring program. Interpretation of moisture content profiles obtained as part of this monitoring program led to important lessons on the cover configuration that was required to satisfy its design criteria.

While the covers were originally designed as unsaturated soil covers, geosynthetics ended up playing an important (and unanticipated) role in their behavior and final design. Geosynthetics are polymeric materials used in combination with soil in geotechnical and geoenvironmental projects. Construction of the unsaturated soil covers at the RMA has just been finalized and preliminary information on their post-construction response is being obtained. Information collected as part of this investigation points to important, yet counterintuitive aspects of moisture flow under unsaturated conditions.