4626 HARBOR LN 2018-01-02 MF Import

Geotechnical Engineering Evaluation NGA File No.853512 Fox Residence Underpinning and Retaining Wall Design August 3, 2012 Everett, Washington Page 8 foot minimum embedment criterion should be rejected, and replacement piles should be driven after consulting with the structural engineer on die new pile locations. Due to the relatively small slenderness ratio of pin piles, maintaining pin pile confinement and lateral support is essential to preventing pile buckling. For this, concrete or grout should be used to fill gaps below the existing foundations. Temporary and Permanent ',lopes Temporary cut slope 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 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 he is continuously at the job site, able to observe the subsurface materials 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 Geotcchnical 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 2 Horizontal to 1 Vertical (2HAV). If significant groundwater seepage or surface water flow were encountered, we would expect that flatter inclinations would be necessary. We recommend that cut slopes be protected from erosion. The slope protection measures may include covering cut slopes with plastic sheeting and diverting surface runoff away from the top of cut slopes. 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 appropriate OSHA/W1SHA regulations. Permanent cut and fill slopes should be no steeper than 2H:iV, unless specifically approved by NGA. Also, flatter inclinations may be required in areas where loose soils are encountered. Permanent slopes should be vegetated and the vegetative cover maintained until established. Wall Design and Construction Recommendations The total height of this v,,ll is not known at this time, but should be limited to eight feet, including a minimum recommended embedment of 1.5 feet into competent soils. We have provided a design for an NELSON GEOTECHNICAL ASSOCIATES, INC.