222 W CASINO RD Geotech Report 2022-10-25

GeoTest Services, Inc. May 3, 2019 Mukilteo School District 19-0194 • Limiting the size and type of construction equipment used • Providing gravel 'working mats'over areas of prepared subgrade • Removing wet surficial soil prior to commencing fill placement each day • Sealing the exposed ground surface by rolling with a smooth drum compactor or rubber-tired roller at the end of each working day • Providing up-gradient perimeter ditches or low earthen berms and using temporary sumps to collect runoff and prevent water from ponding and damaging exposed subgrades Seismic Design Considerations The Pacific Northwest is seismically active and the site could be subject to movement from a moderate or major earthquake. Consequently, moderate levels of seismic shaking should be accounted for during the design life of the project,and the proposed structure should be designed to resist earthquake loading using appropriate design methodology. For structures designed using the seismic design provisions of the 2015 International Building Code, the very dense silts sands and gravels underlying the site within the upper 100 feet is classified as Site Class D,according to 2010 ASCE-7 Standard—Table 20.3-1,Site Class Definitions.The corresponding values for calculating a design response spectrum for the soil profile type is considered appropriate for the site. Please reference the following values for seismic structural design purposes: Conterminous 48 States—2015 International Building Code Zip Code 98201 Central Latitude=47.9198, Central Longitude = -122.2375 Short Period (0.2 sec)Spectral Acceleration Maximum Considered Earthquake (MCE)Value of Ss= 1.43 (g) Site Response Coefficient, Fa= 1.0 (Site Class D) Adjusted spectral response acceleration for Site Class D, SMS=Ss x Fa= 1.43 (g) Design spectral response acceleration for Site Class D, SOS=2/3 x SMs=0.953 (g) One Second Period (1 sec)Spectral Acceleration Maximum Considered Earthquake (MCE)Value of S1= 0.55 (g) Site Response Coefficient, Fv= 1.5 (Site Class D) Adjusted spectral response acceleration for Site Class D, SM1=Six Fv=0.825 (g) Design spectral response acceleration for Site Class D, Sol= 2/3 x SM1=0.55 (g) Foundation Support To provide proper foundation support, GTS generally recommends that existing topsoil, existing fill, and/or soft upper portions of the previously placed fill soils be removed from beneath the building foundation area(s) and be replaced with properly compacted structural fill as described in the Fill and Compaction section of this report. In addition, GTS typically recommends that foundation elements for the proposed structure bear entirely on similar soil conditions to help prevent differential settlement from occurring. However, based on the considerable variability and depth of the encountered fill soils within 6