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Geotechnical Engineering Evaluation NGA File No. 1033518 Larsen Property Garage May 8,2018 Everett,Washington Page 9 Temporary and Permanent Slopes Final grading plans were not`available at the time this report was prepared. Temporary excavation stability is a function of many factors, including the type and consistency of soils, depth of the cut, surcharge loads adjacent to the excavation,length of time a cut remains open,and the presence of surface water or groundwater. It is exceedingly difficult under these variable conditions to estimate a stable, temporary, cut slope angle. Therefore,it should be the responsibility of the contractor to maintain safe slope configurations since they are continuously at the job site, able to observe the soil and groundwater conditions encountered and able to monitor the nature and condition of the cut slopes. The following information is provided solely for the benefit of the owner and other design consultants and should not be construed to imply that Nelson Geotechnical Associates,Inc. assumes responsibility for job site.safety. Job site safety is the sole responsibility of the project contractor. For planning purposes, we recommend that temporary cuts in the on-site soils be no steeper than 1.5 Horizontal to 1 Vertical (1.5H:1 V). If significant groundwater seepage or surface water flow were encountered,we would expect that flatter inclinations would be necessary. Extreme care should be taken during the excavation of the garage as to not adversely impact the existing slopes and/or the existing concrete rubble retaining wall above. We recommend that cut slopes be protected from erosion. Measures taken may include covering cut slopes with plastic sheeting and diverting surface runoff away from the top of cut slopes. Excavated material should not be stockpiled any closer than 35 feet from the top of the cuts. We do not recommend vertical slopes for cuts deeper than four feet if worker access is necessary. We recommend that cut slope heights and inclinations conform to WISHA/OSHA standards. If the above inclinations cannot be met due to property line constraints and/or worker access issues, we recommend that shoring be considered for the planned cuts. We are available to provide specific recommendations for temporary shoring once grading plans have been finalized. Permanent cut and fill slopes should be no steeper than 2H:1 V. However, flatter inclinations may be required in areas where loose soils are encountered. Permanent slopes should be planted and the vegetative cover should be maintained until it is established. We should review plans and visit the site to evaluate excavations for this project. Foundation Support Conventional shallow spread foundations should be placed on undisturbed medium dense or better native soils. Medium dense to dense soils should be encountered roughly three to four feet below the ground surface based on our explorations;however, deeper areas of loose soil may be encountered in unexplored areas of the site. Where undocumented fill or less dense soils are encountered at footing bearing elevation,the subgrade should be over-excavated to expose suitable bearing soil. NELSON GEOTECHNICAL ASSOCIATES,INC.