1001 N BROADWAY 2020 EVCC 2025-10-03

The CSZ is considered as being capable of generating earthquakes of magnitudes 8 to 9. No earthquakes on the CSZ have been instrumentally recorded; however, through the geologic record and historical records of tsunamis in Japan, it is believed that the most recent CSZ event occurred in the year 1700. Recurrence intervals for CSZ interplate earthquakes are thought to be on the order of 400 to 600 years. 4.1.2.Seismic Hazards We evaluated the site for seismic hazards including liquefaction, lateral spreading and fault rupture. Our evaluation indicates the site does not have liquefiable soils present and, therefore, also has little to no risk of liquefaction-induced ground disturbance including lateral spreading. There are no mapped faults in the immediate vicinity of the site, with the exception of the Southern Whidbey Island fault zone mapped approximately 6 miles southwest of the site. Our opinion is that there is a low risk of fault displacement resulting in ground rupture at the surface. 4.1.3.2015 IBC Seismic Design Information We recommend the use of the 2015 IBC parameters listed in Table 1 for soil profile type, short period spectral response acceleration (Ss), 1-second period spectral response acceleration (Si) and seismic coefficients (FA and Fv)for the project site. TABLE 1. 2015 IBC PARAMTERS 2016 IBC Parameter Recommended Value Soil Profile Type C Short Period Spectral Response Acceleration,Ss(percent g) 125.9 1-Second Period Spectral Response Acceleration,Sz(percent g) 47.9 Seismic Coefficient, FA 1.0 Seismic Coefficient,Fv 1.32 4.2. Fo.ux-,dations We recommend that the proposed LRC building be supported on shallow spread footings founded on the dense to very dense advance outwash deposits encountered in our borings or on properly compacted structural fill extending down to medium dense to very dense native advance outwash. Existing fill and unsuitable weathered glacial soils should be removed from under the planned LRC building foundations. For shallow foundation support, we recommend widths of at least 24 and 36 inches, respectively, for continuous wall and isolated column footings supporting the proposed building. The design frost depth in the Puget Sound area is 12 inches; therefore, we recommend that exterior footings for the building be founded at least 18 inches below lowest adjacent finished grade. Interior footings should be founded at least 12 inches below bottom of slab or adjacent finished grade. The following recommendations for the building foundations are based on the subsurface conditions observed in the borings. GEOENGINEERS� July22,2019 Pagc5 -� Fk ND.5886-011.00