2600 FEDERAL AVE 2021 PORT OF EVERETT 2025-09-29

Substantive Requirements Review Landau Associates 2.4 Seismic Considerations The site is located in the seismically active Pacific Northwest and could be subject to ground shaking from a moderate to major earthquake. Consequently, moderate levels of earthquake shaking should be anticipated during the design life of the project, and the proposed improvements should be designed to resist earthquake loading. LAI understands that the Port does not intend to improve marine infrastructure or construct any major structures at this time. As such, the Port has elected not to design current improvements to resist seismic hazards, such as liquefaction and lateral spreading. 2.5 Site Classification and Seismic Design Parameters Seismic design will be completed in accordance with the 2015 International Building Code (ICC 2015). The seismic design parameters in Table 2 were developed using U.S. Geological Survey (USGS) seismic design maps for the 2,475-year (2 percent in 50-year exceedance probability) design earthquake. The site includes potentially liquefiable soils and is classified as a Site Class F (ASCE/SEI 2017). Structures constructed on Site Class F soils require a site response analysis; however, ASCE/SEI 7-10 provides an exception for structures with a fundamental period of vibration equal to or less than 0.5 second (ASCE/SEI 2013). For structures that meet this criterion, the site class can be determined with field investigation data. The proposed improvements are anticipated to have a fundamental period of vibration of less than 0.5 second, and Site Class E can be used to complete seismic design. The design earthquake moment magnitude (M) was determined by selecting the earthquake magnitude with the largest hazard contribution, as shown in the USGS seismic hazard deaggregation. Table 2.Seismic Design Parameters Site Class M PGA(g) SS(g) Sl(g) Fa F FPGA TL(s) E 7.11 0.534 1.244 0.442 0.9 2.4 1.166 6 Fa,Fv=site factors for short-period and long-period ranges of acceleration spectrum,respectively FPGA=peak ground acceleration coefficient g=force of gravity M=design earthquake moment magnitude PGA=peak ground acceleration Ss,Sl=0.2-second and 1.0-second period spectral accelerations,respectively TL=long period transition 2.6 Liquefaction and Lateral Spreading Liquefaction generally occurs in loose, granular soils and non-plastic silts, located below the water table. Liquefiable soils lose strength during or shortly after a strong motion earthquake. Based on a review of available geotechnical data, site soils appear to be highly susceptible to liquefaction and liquefaction-induced settlement. Geotechnical Engineering Report 0121049.040.041 Norton Terminal Development&MTCA 3rd Interim Action 2-6 May 7,2021