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May 20, 2022
For the Fairview Avenue Bridge replacement project, Orion chose to use a method for the work/access trestle that had not been used in the past by anyone in the industry. This method involved using helical pile instead of driven pile due to vibration and noise restrictions associated with the close proximity to an adjacent historical building and medical facilities treating cancer patients. The historical building is approximately 4 feet from the new bridge. The use of the helical pile was showcased on an industry website: https://tinyurl.com/Pileworks-Seattle.
This project involved demolition of two existing bridges: one was founded on timber pile; and the other that was closest to the historical building was founded on concrete pile. The contract required complete removal of all piling including the concrete pile that were in very close proximity to the building. Orion proposed to use a concrete shear to cut the concrete piles off underwater at mudline to prevent erosion from occurring to the slope directly adjacent to the historical building. Removing the piles completely would have left voids that would cause the slope to shift, potentially undermining the building. Orion’s method was approved by the owner and its geotechnical consultant.
Due to limited access for equipment and the length of the new bridge (550 feet), the 140,000-pound concrete girders couldn’t be placed with two cranes but instead had to be rolled into their final position using hydraulic jacks, cable winch, and a roller sled on one end with crane support on the other. This method required thinking outside the box and was performed without incident by Orion’s skilled craft workers.