406 SE EVERETT MALL WAY BASE FILE 2018-01-02 MF Import

Auto Mall Associates May 16, 1986 Excavations and Slopes E-2976 Page 6 In no case should excavation slopes be greater than the limits specified in local, state and national government safety regula- tions. Temporary cuts greater than four feet in height should have an inclination no steeper than 1:1 (Horizontal:Vertical) in fills and surficial loose soils and 0.5:1 (H:V) in dense tills. As an alternate to open cuts, temporary shoring can be used in conjunction with vertical cuts. Detailed criteria for shoring systems can be developed later, if needed. All permanent cut and fill slopes should be inclined no steeper than 3:2 (H:V) and 2:1 (H:V), respectively. These recommendations are applicable to slopes with a maximum height of eight feet. If higher slopes are anticipated, we should be contacted for the appropriate design and construction criteria. We also recommend that all excavated slopes be examined by Earth Consultants, Inc. to verify that conditions are as anticipated. Supplementary recommendations can then be developed, if needed, to improve stability, including flattening of slopes or installation of surface or subsurface drains. In any case, water should not be allowed to flow uncontrolled over the top of any slopes. All permanently exposed slopes should be seeded with an appropriate species of vegetation to reduce erosion and improve stability of the surficial layer of soil. Rockeries We understand that rockeries with a maximum height of eight feet may be considered for site development. The construction of rockeries is to a large extent an art not entirely controllable by engineering methods and standards. The design and construction suggestions given in this report are intended to be used as guidelines should the owner of the project elect to use rockeries instead of engineered retaining walls. It is imperative that rockeries, if used, be constructed with care and in a proper manner. The work should be performed by experienced contractors with proven ability in rockery construction. Tlie base course should be set on firm undisturbed native soils at a minimum depth of twelve (12) inches below final adjacent grade. Where there exist retaining cut slopes less than six feet high, or fill slopes less than four feet high, rockeries may be constructed entirely of four -man rock. Rockeries placed in front of six to eight -foot high cut slopes should have one course of six -man rock at the bottom. The remaining courses may be four -man rock. Any fills behind a rockery should be compacted to at least 95 percent relative compaction as determined by ASTM Test Designation D-1557. We do not recommend using rockeries in front of fills more than four feet high unless the fill is stabilized Earth Consultants, Inc.