5001 23RD AVE W Geotech Report 2022-10-25

site-specific shear wave velocity study. The 1 Hz spectral acceleration with 2% probability of exceedance in 50 years is 120-140% g. Subsurface soil conditions at the site are not susceptible to liquefaction. Seismically induced slope instability may occur on a localized or global scale in the steep slope area; however, such an evaluation was beyond our scope of services. A detailed seismic hazards evaluation of the site was beyond our scope of services. CONCLUSIONS AND RECOMMENDATIONS Our scope of services did not include the detailed geotechnical or geologic hazards investigation of the site area, as it was only limited to foundation underpinning and was authorized to provide recommendations for foundation underpinning only. Moreover, our scope of services did not include any detailed seismic hazard evaluation, civil engineering evaluation including any assessment of stormwater or drainage, etc. Our scope of services also did not include the evaluation of the impact of adjacent house structure on the site stability. Structural evaluation or foundation engineering assessment or forensic study of any kind was beyond our scope of services. Based on the results of limited geotechnical evaluation, in our opinion, the site is suitable for the proposed underpinning construction provided following recommendations are strictly followed. It should be noted that our conclusions and recommendations are intended as design guidance. They are based on our interpretation of the geotechnical data obtained during our evaluation and following assumptions: • Proposed/Final foundation and/or site mitigation plans will be reviewed and approved by us; • Proposed foundation mitigation elements will be constructed on level ground with the consideration of the results of our geologic hazards evaluation as described earlier; and • Structural loads will be typical of residential construction. Construction recommendations are provided to highlight aspects of construction that could affect the design of the project. Entities requiring information on various aspects of construction must make their own interpretation of the subsurface conditions to determine construction methods, cost, equipment, and work schedule. HELICAL PIERS (OR EQUAL) Based on the results of our subsurface exploration and geotechnical analyses, we estimated following geotechnical/foundation design parameters for the structural design of helical piers or Project No: 0314-WA19 'e;t3L1 August 07,2019 Page No:7 of 12