9900 19TH AVE SE Geotech Report 2018-01-02 MF Import

d Geotechnical Engineering Report Home Base Warehouse - Everett July 31, 1997 NCA rile No. 213497 Page 7 Permanent cut slopes and structural fill slopes should be no steeper than 2H:IV. Structural Fill General: 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 degree of relative compaction. The areas to receive the fill should be prepared as outlined in the Site Preparation and Grading sub -section of this report. Materials: Imported structural fill should consist of a good quality free -draining granular soil, free of organic and other deleterious material, and be well graded to a maximum size of about 3 inches. Imported, all weather fill should meet these requirements, and also should contain no more than about five percent fines (soil finer than a U.S. No. 300 sieve), based on that fraction passing the U.S. No. 4 sieve. The on -site glacial till deposits contain fine-grained particles and are considered very moisture sensitive. The use of the these soils as fill should be limited to extended periods of dry weather. Even during periods of dry weather, some discing for drying and watering may be necessary to achieve the desired moisture content. We recommend that these soils be considered for fill only if construction takes place during the drier summer months. Soils with a high organic content should not be used as structural fill. Fill Placement: Following subgrade preparation, placement of the structural fill may proceed. All fill should be placed in 8- to 10-inch-thick uniform lifts. Each lift should be spread evenly and be thoroughly compacted prior to placement of subsequent lifts. All structural fill underlying building areas, and within 2 feet of pavement subgrade, should be compacted to at least 95 percent of its maximum dry density. Maximum dry density in this report refers to that density as determined by the ASTM D 1557 compaction test procedure. Fills more than 2 feet beneath sidewalks and pavement subgrades should be compacted to at least 90 percent of their maximum dry density. The moisture content of the soils to be compacted should be within about 2 percent of optimum, so that a readily compactible condition exists. It may be necessary to overexcavate and remove wet soils in cases where NELSON-CoUVRETTE & ASSOCIATES, INC.