1001 39TH ST 2016-01-01 MF Import

.- I �. DAVID L. NELSON AND ASSOCIATES, INC. Consulling Engincering Geology November 27, 1991 Project No. 10591 Page 8 should not- be allowed to di;charge onto sloping ground or to saturate foundation areas. Surface drains should be maintained separately, and should not be interconnected iaith foundation or. wall drains. Structural Fill All fill placed benea'th buildings, pavements, er other settlemer.t sensitive features should be placed as structural fill. Structural fill, by definition, is placed in accordance with prescribed methods and standards, ard is monitored by an experienced geotechnical professional or soils technician. Field monitoring procedures would include the performance of a representative number of in-place density tests to document the attainment of the desired degree of relative compaction. Prior to placement of structural fill the site should be stripped of all vegetation and topsoil materials. The area should then be thoroughly compacted to a dense non-yielding state. Areas to receive structural fill, structural fill materials and structural �ill placement should be approved by a geotechnical consultant. Where foundation or structural fill areas have hecome softened by moisture, some overexcavation and replacement may be necessary. If dewatering is not complete or if the subgrade will be exposed to water again , we recommerd using a 1 to 2 inch rock (railroad ballast) for structural �`.ill . The rock will provide confinement of the underlyin� soils and will not disturb when exposed to water. The depth of overexcavation and thickness of the rock should be determined in thc. field. Foundaticans In our opinion, the use of shallow spread footings founded on the native, undisturbed glacial soils or Whidbey Formation deposits, or on approved structural fill or crushed rock extending t.o these soils, should prove suitable for support of the proposed J dwelling. For footings founded on or within 10 feet of the steep slope, they should extend a minimum of 3 feet into the underlyiny � medium dense soils . Fill should not be used under foundations � located within 10 feet of the steep slope. Also, foundations should extend below a line sloping up from the toe of the slope j in the ravine at an inclinati�n of 2 : 1 (H:V) . For planning purposes, an allowable soil bearing pressure of 2000 pounds per square foot (psf) should be used for design of shallow footings founded into the medium dense to dense glacial outwash sands, structural fill or �rushed rock. The suggested soil bearing capacities use a factor of safety of 2 and are based on the following conditions : Yjfn