4704 HARBOR LN 2018-01-02 MF Import

' Geotechnical Engineering Evaluation Anderson Landslide Repairs 4704 Harbor Lane Everett, Washington September 15, 2009 NGA File No. 816909 Page 16 Protection of the setback and steep slope areas should be performed as required by the City of Everett. Specifically, we recommend that the top of slope not be disturbed or modified through placement of any fill or removal of the existing vegetation. No additional material of any kind should be placed on the slope or be allowed to reach the slopes, such as excavation spoils, lawn clippings, and other yard waste, trash, and soil stockpiles. 'frees should not be cut down or removed from the slope unless a mitigation plan is developed and approved by the City of Everett. Vegetation should not be removed from the slopes. Replacement of vegetation should be performed in accordance with the City of Everett code. Any proposed development in the area bet%%,cell the house and the slope, including the pool and jacuzzi area should be the subject of a specific geotechnical evaluation. Under no circumstances should water be allowed to concentrate on the slopes. Shoring Wall General: A shoring wall up to 14 feet in exposed height is recommended to stabilize the site slope. 'file wall should extend roughly from the eastern property line to within 40 :'ect of the western property line, as shown on Figure 6. The tree debris that litters the slope should be removed and hauled off site as soon as practical. 'file most feasible shoring system is a solider pile wall. A solider pile wall typically consists of a series of steel 1i-beams placed vertically at a certain distance from one another (typically six to ten feet). The beams are usually placed in drilled shafts that arc filled with concrete or grout. The concrete shafts are typically embedded below the bottom of the planned excavation a distance equals one to two times the height of the cut to be shored, if tic -backs are not used. The steel beams are extended above finished ground surface to provide shoring capabilities for the cut. The beams are typically spanned by pressure treated timber lagging. 'file It -beam size, shall diameter, shaft embedment, and pile spacing arc dependent on the nature of the soils anticipated in the cut and at depth, cut height, drainage conditions, the need for tic -backs, and the final geometry. Tic -backs extending into the native stable soils behind the shoring wall will be needed to provide additional lateral resistance for the wall and reduce loading onto the lower slope. NELSON GEOTECNNICAL ASSOCIATES, INC.