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Pacific Ridge — DRH, LLC ES-7852.01 March 15, 2022 Page 9 Seismic Design The 2018 International Building Code (2018 IBC) recognizes the most recent edition of the Minimum Design Loads for Buildings and Other Structures manual (ASCE 7-16) for seismic design, specifically with respect to earthquake loads. Based on the soil conditions encountered at the test pit locations, the parameters and values provided below are recommended for seismic design per the 2018 IBC. Parameter Value Site Class D* Mapped short period spectral response acceleration, Ss (g) 1.392 Mapped 1-second period spectral response acceleration, S, (g) 0.495 Short period site coefficient, Fa 1.000 Long period site coefficient, Fv 1.805t Adjusted short period spectral response acceleration, SMs (g) 1.392 Adjusted 1-second period spectral response acceleration, Snot (g) 0.893t Design short period spectral response acceleration, SIDS (g) 0.928 Design 1-second period spectral response acceleration, Sot (g) 0.595t Assumes medium dense to dense native soil conditions, encountered to a maximum depth of 8.0 feet bgs during the April 2020 field exploration, remain medium dense to dense to at least 100 feet bgs. t Values assume Fv maybe determined using linear interpolation per Table 11.4-2 in ASCE 7-16. As indicated in the table footnote, several of the seismic design values provided above are dependent on the assumption that site-specific ground motion analysis (per Section 11.4.8 of ASCE 7-16) will not be required for the subject project. ESNW recommends the validity of this assumption be confirmed at the earliest available opportunity during the planning and early design stages of the project. Further discussion between the project structural engineer, the project owner, and ESNW may be prudent to determine the possible impacts to the structural design due to increased earthquake load requirements under the 2018 IBC. ESNW can provide additional consulting services to aid with design efforts, including supplementary geotechnical and geophysical investigation, upon request. Liquefaction is a phenomenon where saturated and loose soil suddenly loses internal strength and behaves as a fluid. This behavior is in response to increased pore water pressures resulting from an earthquake or another intense ground shaking. In our opinion, site susceptibility to liquefaction may be considered very low. The composition and relative density of the native soil were the primary bases for this opinion. Earth Solutions NW, LLC