1809 HOLBROOK AVE 2018-01-02 MF Import

Terhune Homes, Inc. JN 99028 February 25, 1999 Page 6 over time. Drovisions for maintenance, such as access to the rockery, should be considered in the design. In general, we recommend that rockeries have a minimum dimension of one-third the height of the slope cut above them. Tiered ; ockeries are not recommended, unless there is sufficient space to construct upper tiers that do not exert lateral pressure on the lower tiers. The base of a tiered rockery's upper wall should be set back from the rear of the lower rocks an amount equal to the height of the lower tiers. Excavations and Slopes Excavation slopes should not exceed the limits specified in lucal, state, and national government safety regulations. Temporary cuts to a depth of about 4 feet may be attempted vertically in unsaturated soil, if there are no indications of slope instability. Based upon Washington Administrative Code (WAC) 296, Part N, the soil type at the subject site would be classified as Type B. Therefore, temporary cut slopes greater than 4 feet in height cannot be excavated at an inclination steeper than 1:1 (Horizontal:Vertical), extending continuously between the top and the bottom of a cut. The above recommended temporary slope inclination is based on what has been successful at other sites with similar soil conditions. Temporary cuts are those that will remain unsupported for a relatively short duration to allow for the construction of foundations, retaining walls, or utilities. Temporary cut slopes should be protected with plastic sheeting during wet weather. The cut slopes should also be backfilled or retained as soon as possible to reduce the potential for instability. Please note that sand can cave suddenly and without warning. Utility contractors should be made especially aware of this potential danger. All permanent cuts into native soil should be inclined no steeper than 2.5:1 (H:V). Fill slopes should also not be constructed with an inclination greater than 2.5:1 (H:V). To reduce the potential for shallow sloughing, fill must be compacted to the face of these slopes. This could be accomplished by overbuilding the compacted fill and then trimming it back to its final inclination. 'hater should not be allowed to flow uncontrolled over the top of any temporary or permanent slope. Also, all permanently exposed slopes should be seeded with an appropriate species of vegetation to reduce erosion and improve the stability of the surficial layer of soil. Any disturbance to the existing slope outside of the building limits may reduce the stability of the slope. Damage to the existing vegetation and ground should be minimized, and any disturbed areas should be revegetated as soon as possible. Soil from the excavation should not be placed on the slope, and this may require the off -site disposal of any surplus soil. Drainage Considerations Foundation drains are required where (1) crawl spaces or basements will be below a structure, (2) a slab is oelow the outside grade, or (3) the outside grade does not slope downward from a building. Drains should also be placed at the base of all earth -retaining walls. These drains should be surrounded by at least 6 inches of 1-inch-minus, washed rock and then wrapped ir. non -woven, geotextile filter fabric (Mirafi 140N, Supac 4NP, or similar material). At its highest point, a perforated pipe invert should be at least 6 inches below the bottom of a slab floor or the level of a crawl space, and it should be sloped for drainage. Drainage should also be provided inside the 7/ GEOTECH CONSULTANTS, INC. `/