4107 OLIVE ST 2018-01-02 MF Import

DID L. NELSON AND ASSOCIATES, INC. consultinf Enilnee,ing Geology July 13, 1990 _ Project No. 9490 Page 6 ground or to saturate foundation areas. Surface drains should be maintained separately, and should not be interconnected with foundation or wall drains. structural Fill All fill placed beneath buildings, pavements, or other settlement sensitive features should be placed as structural fill. Structural fill, by definition, is placed in accordance with prescribed methods and standards, and 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 ill the site degree of relative compaction. Prior to placement of structural t should be stripped of all vegetation and topsoil materials. The area should then be thoroughly compacted to a dense non -yielding state. Slope areas with surface grades in excess of 20% which are to recieve structural fill should be benched horizontally on 3 foot vertical intervals, prior to surface compaction. Areas to receive structural fill, structural fill materials AM structural fill placement should be approved by a geotechnical consultant. Where foundation or structural fill areas have becor..e 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 recommend using a 1 to 2 inch rock (railroad ballast) for structural fill. The rock will provide confinement of the underlying soils and will not disturb when exposed to water. The depth of overexcavation and thickness of the rock should be determined in the field. Foundations 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 to these soils, should prove suitable for support of the proposed dwellings. For planning purposes, an allowable soil bearing pressure of 2000 pounds per square foot (psf) should ba used for design of shallow footings founded into the medium dense to dense