3620 36TH PL NE 2018-01-02 MF Import

Backfill for Drains" per Washington State Department of Transportation (WSDOT) standard specifications Section 9-03.12(4). The perimeter drains should be sloped to drain by gravity, if practicable, to a suitable discharge point, preferably a storm drain. We recommend that the cleanouts be covered, and be placed in flush mounted utility boxes. Water collected in roof downspout lines must not be routed to the footing drain lines. 4.4.6 Construction Considerations Subgrade disturbance may occur if footings are completed during wet weather. If wet weather construction is planned, we recommend that all footing subgrades be protected using a 2- to 3-inch thick lean concrete mud mat or a flinch thick layer of clean crushed gravel. The mud mat or gravel layer should be placed the same day that the footing subgrade is excavated and approved for foundation support. jWe recommend that the condition of all footing excavations be evaluated by a representative of our firm immediately before any structural fill, mud mat, steel or concrete is placed, to evaluate if the work is being completed in accordance with our recommendations and that subsurface conditions are as anticipated. 4.5 SLAB -ON -GRADE FLOORS Slabs may supported on -grade providing the subgrade soils are prepared as recommended in Section 4.2, the structural fill pad is properly placed and compacted, and that the preload is applied in accordance with the recommendations discussed in Section 4.3. We recommend that the slabs be founded on at least a 2-foot thick structural fill pad placed over the native soils. For slabs designed as a beam on an elastic foundation, a subgrade modulus of 30 pounds per cubic inch (pci) may be used for subgrade soils prepared as recommended. We recommend that the office building slab and other moisture sensitive floor slabs be underlain by a capillary break consisting of a 6-inch minimum thickness of P/z-inch minus crushed rock with negligible sand and silt. The capillary break can be considered part of the recommended 2-foot minimum thickness j structural fill pad. If moisture -sensitive coverings are used on interior floor slabs such as the office building, a vapor barrier, such as plastic sheeting, should be installed between the slab and the base course. The contractor should be made responsible for maintaining the integrity of the vapor barrier during construction. A 2- inch-thick layer of sand should be placed over the vapor barrier to protect it during construction and to aid in uniform curing of the concrete. The structural engineer should be consulted if the contractor proposes I . deleting the 2-inch-thick layer of sand. 4.6 LATERAL EARTH PRESSURE ON PERMANENT WALLS Conventional cast -in -place walls may be necessary for smal! retaining structures located on -site. The lateral soil pressures acting on conventional cast -in -place subsurface walls will depend on the nature, density and configuration of the soil behind the wall and the amount of lateral wall movement which can occur as backftll is placed. Z3 G e o E n g i n e e r 9 18 File No. 11625-001.02J123003