Degenkolb Engineers designed the structural system for the Ocosta Elementary School and tsunami vertical evacuation refuge. The roof of the school gymnasium is a designated safe refuge and it has a capacity for over 1,000 people. Performance-based design methodologies were implemented to ensure that the structure would be able to resist a Cascadia earthquake while having sufficient capacity to resist subsequent tsunami inundation forces. Degenkolb worked closely with the University of Washington-based inundation modeling team to develop key design parameters, resulting in a safe refuge which is 55 feet above sea level and 28 feet above grade. The building features reinforced concrete stair towers and concrete-encased columns to protect against impact forces, drilled piles to resist scouring and liquefaction, and contains measures to prevent progressive collapse due to extreme impact loads.
Degenkolb Engineers served as a Technical Advisor for Project Safe Haven: Tsunami Vertical Evacuation on the Washington Coast. The project utilized a grassroots process to develop vertical evacuation strategies for several communities in both Grays Harbor and Pacific counties. The Project Safe Haven process included both World Cafe methods and community design charrettes to allow community member consideration of evacuation options ranging from buildings and towers to raised earthen berms.
Degenkolb provided the team with structural engineering guidance for each evacuation option. These conceptual designs were used to develop cost estimates for future planning purposes. Both the Ocosta School site and Long Beach Elementary were identified as safe haven locations due to the large number of students and staff present during much of the year.
The Tokeland community and nearby communities on the Washington coast are susceptible to tsunamis induced by earthquakes along the Cascadia Subduction Zone. A vertical evacuation tower provides refuge from a tsunami in areas where reaching high ground is not possible in the time between the earthquake and the tsunami.
Degenkolb worked with the Shoalwater Bay Indian Tribe On a conceptual design for a tsunami vertical evacuation tower on the Tokeland Peninsula. The structure was designed to provide refuge for over 400 people and was recently awarded a FEMA grant to fund the design and construction cost.
Degenkolb Engineers is working with the City and County of Honolulu on improving the tsunami safety along the coast of Oahu by developing a Tsunami Ready structural evaluation program. This leverages the recently-published national standard ASCE 7-16, which includes provisions for tsunami loads and effects on building structures, by developing an evaluation criteria to screen and evaluate buildings which may be viable for tsunami vertical evacuation. The evaluation procedures are developed similar to ASCE 41-13 – Seismic Evaluation and Retrofit of Existing Buildings to take advantage of the familiarity of an existing evaluation procedure.
Degenkolb has developed both a checklist-based screening and a detailed evaluation procedure to determine which existing buildings may be used for tsunami vertical evacuation purposes. Although this procedure focuses on the typical construction on Oahu, it can also be expanded to other tsunami-prone regions of the world.