20 SW EVERETT MALL WAY Geotech Report 2018-01-02 MF Import

i r Campbell-Fleury Investments/Mallwest Center i ' 9 April 1986 W-3103-1 Page 6 r � 4.2 Structural Fill r All fill placed in building areas, or beneath driveways and roads should be placed � in accordance with recommendations herein for "structural fill". Prior to placement of structural fill, surfaces to receive the soils should be prepared as previously discussed. Structural fill should be placed in loose lifts not exceeding 8 inches in thickness. Individual lifts should be mechanically compacted to a uniform density I of at least 90 percent of the modified Proctor dry density (ASTM:D 1557). We recortmend that a representative of our firm be present during the placement of r structural fill to observe this work and perforrn a representative numbe^ of in- place density tests. In this way the adequacy of earthwork may be evaluated as fgrading progresses. I L L: The suitability of soil for structural fill use depends primarily on the gradation and moisture content of the material when it is placed. As the amount of fines (that portion passing the U.S. No. 200 sieve) increases, soils become increasingly sensitive to small changes in moisture content and adequate compaction beComes more difficult or impossible to achieve when. the soil is only slightly wetter than optimum. Soils which contain more than about 5 percent fines by weight, such as the bulk of the near-surface site soils, cannot be readily compacted to a firm, non-yielding condition when the moisture content is more than about few percent from optimum. If the site work is to be completed in wet site or wet weather conditions, it may be necessary to import a select "clean" well-graded soi' for fill purposes. Fines content for select fill should be limited to 5 percent or less (based on that portion passing the No. 4 sieve) in order to allow work to proceed in a wide variety of weather conditions. In all cases, structural fill should be free of debris or other deleterious material. It should ideally be limited to a maximum size of 6 inches or less.