4003 NASSAU PL 2016-01-01 MF Import

' ' ' 1 1 ' � � ' �. �_ � I. i. Geotechnical Engineering Report Kvernmo Single-Family Res�dence 4003 Nassau Place, Everett September 17, 200.'. NGA rile No. 356: 02 Page 12 Resistance to lateral loads may also be provided by passive resistance the below ground portion of the foundations. Passive resistance may be calculated as a triangular equivalent fluid pressure distribution, using an equivalent tluid densiry of 150 pounds per cubic foot (pc�. This recommended value incorporate a safety factor of 2.0 applied to the estimated ultimate value. To achieve this value of passive resistance, the grade beams or foundations should be poured "neaP' against the existing soils, or compacted fill could be used as backfill around the footings. The compacted zone in front of the gade beams or footings should extend a horizontal distance equal to at least three times the width of this element. We recommend that the upper 1 foot of soil be neglected when calculating the passive resistance. Slabs-on-Grade As mentioned earlier, if some slab settlement and future maintenance is acceptable, the slabs could be •`floated" on the existing fill, providing some surficial fill treatment is perfortned as described hereon. To improve the material underlying slab areas and reduce the likelihood of slab settlement, we recommend that the upper 2 feet of the material found in the slab area be reworked to suuctural fill specifications. "fhis could be accomplished by compacting these soils with a heavy vibrating roller, if conditions warrant, or overexcavation and replacement with imported material if subgrade compaction was no feasible. 7'he abiliry to compact the on-site material will depend on organic and moisture content at the time of construction. After the recommended treatment, additional swctural fill or the slab uction could be placed on the prepared subgrade. We should be retained to observe slab subgrede preparation and evaluate structural fill material and fill placement. Even with the recommended treatment, some settlement of the underlying fill should be anticipated. To reduce the adverse impact of the settlement on the slabs, the slabs should be adequately reinforced to withstand differential settlement. This should be evaluated by your swctural engineer. IWe recommend that all Floor slabs be underlain by at least 6 inches of free-draining sand or gavel for use - as a capillary break. We recommend that the capillary break be hydraulically connected to the footing drain system to allow frce drainage from under the slab. A suitable vapor barrier, such as heavy plastic 1- sheeting (6-mil or thicker), should be placed over the capillary break material. An additional 2-inch-thick 'NELSON GEOTECHNICAL ASSOCIATES, INC l��,