Workers at the U.S. Department of Energy’s Office of Environmental Management (EM) Portsmouth Site in Pike County, Ohio, have completed construction of the fourth cell at the On-Site Waste Disposal Facility (OSWDF), marking a key milestone in the site’s cleanup efforts. The Portsmouth Gaseous Diffusion Plant, covering 1,200 acres of the 3,777-acre site, operated from 1954 to 2001, producing enriched uranium for nuclear weapons and later for commercial reactors. Enrichment ceased in 2001 after weapons-grade production was suspended post-Cold War.

Crews at the Portsmouth Site install a thick geomembrane lining material inside the new cell at the On-Site Waste Disposal Facility

Environmental cleanup at the site began in 1989, managed by EM in collaboration with the U.S. and Ohio Environmental Protection Agencies. Decontamination and decommissioning started in 2011. In 2021, the demolition of the 56-acre X-326 Process Building was completed three months ahead of schedule, with debris and impacted soils placed in the OSWDF. This engineered facility uses a multi-layer liner and cap system to safely contain demolition materials, protecting public health and the environment. All water runoff from the demolition and OSWDF is treated in specialized facilities.

Demolition of the 33-acre, two-story X-333 Process Building, the second of three former uranium enrichment structures, is currently underway. Federal Project Director Jud Lilly stated: “Completion of the fourth OSWDF cell is essential to completing the next phase of the cleanup mission at the Portsmouth Site. The fourth cell is needed for disposal of debris from the demolition of the next process building.” Debris placement from X-333 into the new cell is expected to begin this spring.

Last April, EM crews excavated a seven-acre area for the fourth cell, adding select fill, a clay liner, and geosynthetic material to complete its construction. Paul Larsen, director of OSWDF at Fluor-BWXT-Portsmouth, EM’s contractor for the site, said: “We are proud of the quality construction of the cell while maintaining a safe work environment.”

Two additional OSWDF cells are slated for completion later this year. The facility will ultimately include 10 cells, with the potential for two extra contingency cells to accommodate debris and soils meeting waste acceptance criteria from the ongoing deactivation and demolition projects. This progress supports the safe and efficient cleanup of the Portsmouth Site, advancing environmental restoration goals.