1802 75TH ST SW Geotech Report 2022-10-25

we Recommendations regarding settlements and sliding friction given above for spread footings also apply to slab foundations. Drilled shaft foundations should penetrate into the glacial till a minimum of 3 feet and should be at least 24 inches in diameter. The maximum bearing value at the tip of the shaft should not exceed 10,000 psf. Total settlements of drilled shaft foundations are expected to be 1/4 to 1/2 inch. The resistance of drilled shafts to lateral loads should be based on an equivalent fluid density of 365 pcf acting on an effective width of two shaft i diameters. The passive resistance on the shaft to a depth of one foot below finished site grade should be ignored due to disturbance from shaft installa- tion. Frictional resistance along the shaft•of the drilled pier may be taken as 200 psf. We understand that a computer program (MFAD) will be used for design of the drilled shaft foundations. The soil may be characterized by the following soil parameters for use in the MFAD computer program: CONSTRUCTION OBSERVATIONS We recommend that Converse Consultants NW observe site grading to ensure that the recommendations of this report and the provisions in the construction specifications are properly completed during construction. Activities should include observations of soil surfaces prior to placing fill (in overexcava- tions) or backfill, compaction testing of backfill, testing of proposed imported fill, and observation of foundation and slab bearing surfaces, Converse Consultants NW