Challenge

The US Department of Energy (DOE) created the Idaho Cleanup Project (ICP) in order to safely close and dispose of nuclear and radioactive waste at a former nuclear base in Idaho. The Subsurface Disposal Area (SDA) within the Radioactive Waste Management Complex in particular needed to be closed and covered, but the final surface barrier needed to meet a required 1,000-year performance period and all state and regulatory requirements for radioactive and hazardous waste.

Solutions

The prime contractor for the ICP contracted GLA to complete the engineering design and associated regulatory documents for the final evapotranspiration (ET) surface barrier at the SDA. Our team began by summarizing and categorizing the regulatory and other requirements in a technical and function requirements document.

Based on the regulatory and site-specific requirements, our team produced a cover design that achieves a long-term protective solution for the 97-acre landfill. The design documents include our team’s design for the cover, including construction drawings, technical specifications, and a design report along with other regulatory documents. The landfill is to be covered with compacted material to set the grade for the ET barrier materials. Our design also included provisions for monitoring, including a large lysimeter moisture collection system, a weather station, multiple sensor arrays, and an automated data recording system. The cover design was reviewed and approved by the DOE, the U.S. Environmental Protection Agency, and the Idaho Department of Environmental Quality, meeting all required state and federal regulations.

Results

GLA’s cover design achieves the best possible performance for a number of goals. The cover is designed to minimize water infiltration to equal or outperform standard regulatory designs. The design is soundly engineered, constructible, and cost-effective, that will protect the environment and human health for an extended period.