The National Park Service has a plan to stabilize Spruce Tree House, but needs funding to implement it/Rebecca Latson file
While the National Park Service has identified a plan to allow Spruce Tree House at Mesa Verde National Park to be stabilized and reopened to the public, funding for the work has not yet been identified.
The popular attraction, which houses the third-largest cliff dwelling in the park in western Colorado, with 130 rooms and eight kivas, has been closed to the public since October 2015 because of concerns that layers of sandstone could peel away from the arch at any time and fall on bystanders below. Spruce Tree House may be seen, however, from an overlook near the Chapin Mesa Museum.
Back in 2016, the Park Service pointed out that “[E]arly stabilization work was performed (on the arch) in the 1940s, with additional stabilization work completed in the 1960s. Natural erosion processes, including the settling of the arch, have been affected by the early stabilization work, so that modern engineering techniques may be necessary to ensure continued stability of the arch.”
Under the approved plan, work will include:
- Installation of up to 75 20-foot-long tensioned rockbolts in a net-like pattern to stabilize the overall alcove arch.
- Installation of 120 passive 6- to 8-foot rockbolts to stabilize smaller local rock features.
- Encapsulation of every completed rockbolt with custom-colored mortar that would match the color and texture of the adjacent surrounding sandstone and provide corrosion protection.
- Treatment of shrinkage cracks in the existing concrete plug (installed in 1963) between the sandstone at the back of the alcove arch and the outer face of the alcove roof.
- Removal of loose surface rocks, detached rock slabs, and vegetation (minor scaling) using hand and power tools.
- Installation of several relatively small, rectangular-shaped corbels6 (constructed of reinforced concrete and color matched to the local sandstone) that would be tucked up and under several hanging rock blocks that form part of the alcove’s outer surface. Their position would minimize exposure and visibility.
- Installation of geotechnical instrumentation with remote data logging and transmitting capabilities (located in the park’s headquarters) to constantly monitor the alcove arch’s stability.
The stabilization design would also remove select loose material via scaling. Project work and support areas include the construction site above the alcove, an established off-site material staging area, and temporary access routes.
If funding is identified, work could begin this fall.
