Northwest Demolition was contracted for the demolition of a nine-story poured-in-place concrete structure on the Oregon Health Sciences University (OHSU) campus. The 60-year-old building had been built into the existing hillside, which presented significant safety and environmental challenges to the demolition scope. Northwest Demolition was involved in the early strategic planning phase of the project, creating a geoengineered design for soil and hillside retention. Selective robotic demolition was performed to enable the installation of soil nails, steel whalers, and a large shotcrete wall on the existing seven-story retaining wall.
Once the reinforcement was complete, a high reach excavator was utlized for the top-down structural demolition. For the heavily reinforced elevator shaft, a Brokk robotic excavator suspended from a crane basket was used to prevent an unplanned collapse and ensure a controlled removal process. Throughout the project, careful coordination was required so as to not disrupt the existing hospital operations and emergency traffic. Proximity to an adjacent eye surgery complex necessitated the use of seismometers to ensure work vibrations were being kept below levels deemed safe to perform the sensitive surgeries. Onboard dust suppression equipment and large industrial misters were used to control fugitive dust and minimize risk to air handling equipment and patients with potentially compromised respiratory systems.
During demolition operations, more than 30,000 tons of debris was removed from the congested area, and an additional 8,000 tons of concrete was crushed onsite for future use. The project was completed ahead of schedule, with no productivity impacts to hospital operations and zero safety incidents.