Disposal Cell Progress Continues With New Interim Cover Installation

September 2025 - The Moab UMTRA Project’s disposal cell at the Crescent Junction site, near the Book Cliff mountains. 

The Moab Uranium Mill Tailings Remedial Action (UMTRA) Project recently completed another successful installation of interim cover on a section of its disposal cell.  

The Moab project is part of the U.S. Department of Energy’s Office of Environmental Management (DOE-EM), which oversees the cleanup activities at the Moab site, located along the Colorado River, near Moab, Utah. Since 2009, DOE has been transporting uranium mill tailings by rail from the Moab site to the Crescent Junction site, where the engineered disposal cell is being constructed. 

Disposal cells such as the one at Crescent Junction are designed to isolate radioactive tailings for centuries, and their effectiveness depends on rigorous Quality Assurance (QA) and Quality Control (QC) practices throughout the entire lifecycle of the cell – from design and construction to long-term monitoring. 

As the Crescent Junction cell is filled, the Moab project’s QA/QC program conducts continuous testing to ensure that all design specifications are met. 

Before the tailings leave the Moab site, they are dried and blended to meet the disposal cell specifications. Once transported and deposited at Crescent Junction, the tailings are hauled to a designated area, placed in a uniform layer, moisture conditioned as needed, and compacted.

Each placement area within the cell is known as a controlled lift. Every aspect of a controlled lift – it’s thickness, moisture content, and degree of compaction – is carefully managed to achieve the required density and stability. 

Creation of a controlled lift inside the disposal cell includes placement of tailings by a haul truck, distribution of the tailings by a dozer, and compaction of the tailings by a sheepsfoot roller. 

Automated sensors on haul trucks, dozers and sheepsfoot rollers assist operators in building each lift to specification. QA/QC personnel then perform geotechnical testing to verify density and moisture content. Proper compaction is essential because it reduces settlement, improves structural stability, minimizes water infiltration, prevents differential movement and supports predictable long-term performance. 

Constructing the cell in controlled lifts ensures that every layer in the entire disposal cell meets design specifications. 

Once a section of controlled lifts is complete, a layer of clean, noncontaminated soil is placed over it. This interim cover protects the compacted tailings from erosion and disturbance, reduces infiltration, and provides a stable working surface while additional portions of the cell is filled. It serves as a temporary protective layer until the permanent engineered cover, or cap, is constructed. 

The Moab project anticipates completing the Crescent Junction disposal cell in 2029. At that point, responsibility for the site will transfer to DOE’s Office of Legacy Management (DOE-LM) for long-term stewardship and monitoring.  

Contributor: Barbara Michel