EXH1166044372

FROM: Douglas Lindquist, Barry Chen, P.E.,and Mike Bailey, P.E.,Hart Crowser, Inc. RE: Seismic Basisof Design Third Runway Project .... J-4978-14 •.)o '" _ O' This memo provides support information to HNTB and the Port of Seattle to select a seismic basis of design event for final project design analyses. This memo presents a comparison of analyses by Hart Crowser for the 475- and 975-year return interval seismic events for representative embankment and MSE wall design components. FalrD¢3r_ Summary Selection of the 475- or the 975-year event as the seismic basis of design event impacts the following areas of design for the Third Runway project: J_..... o:, 1. Spatial extent of ground improvement needed to mitigate liquefaction (small effect); 2. Extent of embankment reinforcement below MSE walls to prevent seismic instability (moderate effect); J...... 3. Factor of Safety in slope stability analyses (moderate effect); and 4. Magnitude of deformation of the MSE walls (moderate to large effect). The 475-year return period corresponds to a I0 percent probability of exceedence in 50 years, whereas the 975-year return period corresponds to a 5 percent probability of Lon__each =xceedence in 50 years. For comparison, we understand the Port of Seattle used the 475- , event for design of the South Terminal Expansion and for analysis of deepening the ber_,..-at the Terminal 5 Wharf. Portland Comparative Analyses Resultsof our analyses for representative sections are described in this memo, to provide the basis for comparing the effect of using one design event or the other. The…

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PSCAA Advisory Council Meeting Agenda
Add to CalendarMWednesday Mar 11, 9:00am - 11:35am
1904 3rd Avenue, Suite 105, Seattle, WA 98101
Call to order – Roll Call – Quorum Established – Land Acknowledgement We would like to acknowledge that our Agency operates in four present-day counties, which are the traditional lands of the Coast Salish people, past and present. This acknowledgement does not take the place of authentic relationships with indigenous communities in our jurisdiction and [...]