Canemah Bluff Natural Area
Oregon City, Oregon
Hart Crowser completed rockfall and landslide assessments for the Canemah Bluff Natural Area located in an area of steep cliffs and talus slopes. Planned development included an overlook at the edge of a cliff and pedestrian trails and bridges through unstable talus slopes. We completed field assessments of the cliffs and talus slopes to provide recommendations for the proposed development. Our work included rapelling traverses to determine the risk of rock slope failure at the overlook, a reconnaissance of talus slopes for siting the paths and bridges, and design recommendations for siting these structures within the unstable areas.
Challenges of the project included:
- Ensuring the planned overlook was in an area of stable rock to protect public safety and provide longevity of the overlook. This was accomplished by collecting rock data via vertical rope rappels, analyzing the data and designing economical rockfall stabilization measures to stabilize the bluff.
- Protecting the highway, and particularly highway traffic, during field work. This was accomplished by closure of one lane of Highway 99E during the rappels. The closure required permits from ODOT and timing the work to coincide with allowable lane closure windows of this busy highway.
- Working within the natural area without damaging sensitive and protected plants. This was accomplished by carefully planning rappel locations with Metro, using hand- rather than truck-mounted drills for explorations, and coordinating logistics so areas of sensitive plants were avoided.