9930 19TH AVE SE 2018-01-02 MF Import

Geotechnical Engineering Report Home Base Warehouse - Everett July 31, 1997 NCA File No. 213497 Page 9 Although structural loading informatiop was not available at the time of this study, based on our experience with similar structures supported on similar soil conditions and for the recommended allowable soil bearing pressures, we estimate that the potential total settlement is less than 1 inch, and that the potential differential settlement is less than 3/4 inch over a distance of about 20 feet. Lateral Pressures The lateral pressure acting on retaining walls is dependent on the nature and density of the soil behind the wall, the amount of lateral wall movement which can occur as backfill is placed, wall drainage conditions, and the inclination of the backfill. For walls that are free to yield at the top at least one - thousandth of the height of the wall, soil pressures will be less than if movement is limited by such factors as wall stiffness or bracing. We recommend that yielding walls supporting horizontal backfill and not subjected to hydrostatic forces be designed using an equivalent fluid density of 35 pounds per cubic foot (pcf). Non -yielding walls supporting horizontal backfill and not subjected to hydrostatic forces should be designed using an equivalent fluid density of 55 pef. These lateral soil pressures do not include the effects of surcharges such as traffic loads, hydrostatic pressure, inclined backslopes, or other surcharge loads. Surcharge effects should be considered, if appropriate. We can provide recommendations for surcharge loads as they become apparent, if desired. Lateral loads can be ref by friction between the foundation and subgrade and the passive resistance acting on the below-er: undation. For the latter, the foundation must be placed "neat" against the undisturbed soil, or bat '% ,. A with a clean, free -draining, compacted structural fill; and the ground surface adjacent to the footin, must be level for a distance from the footing of at least 2 times the depth of the footing. We recommend !hat lateral passive resistance be calculated by using an equivalent fluid density of 250 pcf. An allowable coefficient of friction between footings and the subgrade of 0.4 may be used, and should be applied to the vertical dead load only. These values include a factor of safety of 1.5 and 2.0 for friction and passive resistance, respectively, applied to the estimated ultimate soil strength. The above wall pressures assume that the wall is dra;ned and hydrostatic pressures do not develop. Wall drains are discussed in the Subsurface Drainage sub -section of this report. NELSON-COUVRETTE 6 ASSOCIATES, INC.