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June 13,2023 <br />HWA Project No. 2022-188-2 1 <br />and are suitable for support of the proposed buildings. The site is also impacted by high ground <br />water levels during the summer months due to irrigation. Details regarding our <br />recommendations for design and construction of the proposed improvements are provided in the <br />following sections. <br />4,2 Srrsutc DnstcN Panc,Nlnrnns <br />The contribution of potential earthquake-induced ground motion from known sources is included <br />in the probabilistic ground motion maps developed by the United States Geologic Survey <br />(USGS). Design data seismic site charucterization and design recommendations based on USGS <br />mapping and analysis are implemented in the 20ls International Building Code (lBC). As part <br />of this code, the design of structures must consider dynamic forces resulting from seismic events. <br />These forces are dependent upon the magnitude of the earthquake event as well as the properties <br />of the soils that underlie the site. <br />As part of the procedure to evaluate seismic forces, the 2018 IBC requires the evaluation of the <br />Seismic Site Class, which categorizes the site based upon the characteristics of the subsurface <br />profile 100 feet below the proposed foundation. The Site Class can then be determined in <br />accordance with Section2}.3 of ASCE 7-16, andthe corresponding values of Fu and Fu <br />determinedfromTables 11.4-1 and 11.4-2ofASCE7-l6.InSection l1.4.8ofASCE7-16,itis <br />stated that a site-specific ground motions hazard analysis is required on sites with seismically <br />isolated structures and structures with dampening systems when Sr greater than or equal to 0.6. <br />Provided these conditions do not pertain to the proposed structures a site-specifrchazard analysis <br />is not required. Based on the obtained SPT blow counts noted in our boring logs and <br />extrapolated to a depth of 100 feet, the site classifies as Site Class "C". <br />Should the information used as a basis for this design be incorrect, HWA should be notified to <br />provide appropriate recommendations. The associated probabilistic ground acceleration values <br />and site coefficients for the general site area were obtained from the Applied Technology <br />Council Seismic HazardMaps. The risk targeted seismic values and coefficient are presented in <br />Table l below. <br />82022-188-21 KCTS - Final Geotechnical Report HWA GEOSCIENCES INC