Expanding a 34-Year-Old Superfund Solution
The Page Repository, a specially engineered disposal facility serving the Bunker Hill Superfund cleanup across the Silver Valley, is undergoing a significant expansion to handle volumes of contaminated material that have doubled since its original design.
Built in the early 1990s to consolidate contaminated soil and mine waste from remedial projects throughout the Box, the repository was envisioned by the EPA in its 1992 Operable Unit 2 Record of Decision as a permanent containment location. The Idaho Department of Environmental Quality designs and operates the facility, which accepts waste from remedial actions, the Institutional Controls Program, the Roads Program, and the Basin Property Remediation Program.
When engineers originally designed the repository, they estimated it would receive roughly 15,000 cubic yards of contaminated material annually. However, recent cleanup projects are now generating closer to 30,000 cubic yards per year—nearly double the anticipated volume. The expansion, known as Cell 6, represents the repository’s response to that increased demand.
Engineering New Capacity While Managing Constraints
The repository operates under strict environmental and structural limits. The facility can accommodate only about 5 feet of contaminated material per construction season, a constraint imposed by the engineered design that uses clean, durable construction materials as a stable foundation. Despite this seasonal limitation, the accumulating volume of cleanup waste has made expansion necessary.
Current work at the site involves stockpiling concrete materials to build out Cell 6. Contractors will remove reinforcing steel from the concrete and process the material to meet the repository’s design specifications. Cell 6 is engineered to be deeper than previous expansion areas and includes additional foundation material to ensure the finished repository remains at least 1 foot above the 100-year flood elevation—a critical safeguard for long-term containment integrity.
The incorporation of large concrete pieces into the repository has been standard practice since the facility’s early expansions. Water-quality monitoring to date has not detected adverse impacts from the use of concrete in the repository’s construction, providing confidence in the approach as Cell 6 moves forward.
The Cost of Containment
The expansion effort addresses not only volume but also cost efficiency. Recycling concrete and other materials from cleanup sites at an estimated cost of roughly $50 per cubic yard is substantially less expensive than purchasing all material from commercial quarries—a scenario that could cost approximately $7.5 million for a full year’s worth of contaminated material.
Once Cell 6 is complete, no further foundation expansion is planned for the Page Repository. This final phase of growth reflects both the scope of remaining cleanup work in the Silver Valley and the repository’s critical role as the consolidation point for decades of mining-legacy remediation.
The Page Repository remains the linchpin of the Bunker Hill Superfund cleanup strategy, offering a engineered solution to a challenge that will persist for years to come. As cleanup projects continue throughout the Box, the facility’s capacity to safely contain and manage contaminated materials—now expanded and designed to handle the accelerated pace of recent remediation efforts—ensures that the cleanup process can continue without interruption.
For more on Silver Valley community projects and environmental stewardship, see coverage of Pinehurst’s America’s 250th Birthday celebration.