Sources Sought Spruce Tree House Arch Stabilization

The National Park Service (NPS) in support of Mesa Verde National Park is seeking information from qualified contractors of interest on a project to stabilize the alcove cliff lead edge above the prehistoric Spruce Tree House (STH) cliff dwelling. The nose of the alcove contains a thin arch delineated by a persistent curved crack, which extends about 270 ft north from above the south end of the alcove. The crack between the alcove roof and the arch can be up to several feet wide. The arch cross section is roughly 10 ft thick by 20 ft high. Spruce Tree House cliff dwelling and the alcove it was constructed is in a culturally and environmentally sensitive environment, located adjacent to the park headquarters district. A 1960s investigation led to a stabilization program that included rockbolts at the southern end and a thorough cleaning and grouting of the crack along the complete length of the arch. Recent detailed numeric engineering analyses indicate that this stabilization is nearing the end of its life cycle and may fail. A stabilization design of installing additional longer and reticulated rockbolts to stabilize the main arch, shorter rockbolts to stabilize individual arch rock blocks, selective vegetation removal and rock scaling of the cliff, treatment of the crack between the arch and alcove cliff, and instrumentation to monitor the installed stabilization has been completed by a geotechnical and structural engineering consultant for the NPS.

Division 02 -	Existing Conditions, Subsurface Investigation.
Division 31 -	Earthwork, Grading, Erosion and Sedimentation Controls, Stabilization Measures for Erosion and Sedimentation Control, Earthwork Methods, Soil Stabilization, Soil Mixing Stabilization, Rock Stabilization.