Laserfiche WebLink
� Proposed Modification [o thE Residence ot Joel & Kathy Larsen Februar; 12, 2004 <br />Everett, Washington ORA Project Number: 04-065-Report 1 <br />1 <br />� location of structures and foundation loads can change and because subsurface <br />conditions are not always similar to those encountered in the borings, the geotechnical <br />engineer must be contacted for review and possible revision of the recommendations if <br />( discrepancies are noticed. <br />6. RECOMMENDAT�ONS <br />The following sections present recommendations regarding seismic considerations, <br />foundations, lateral earth pressures, and for earthwork, excavations, drainage, and <br />groundwater. <br />6.1 Seismic Considerations <br />According to Figure No. 16-2 of the 1997 edition of the Uniform Building Code (UBC), <br />the project site is in Seismic Zone 3. According to Table 16-J of the UBC, the site soil <br />profile is best represented by a Soil Profile Type S�. The near-surface Silty SAND soils <br />at this site may be susceptible to liquefaction. <br />6.2 Foundations <br />Due to the vertical extent of the weak, compressible soils beneath the primary residence <br />building, we recommend that the building loads be transmitted to the underlying, <br />stronger, relatively incompressible, stiff to hard SILT (ML) soils encountered at an <br />approximate elevation of 492 and below by use of a deep foundation system. Deep <br />foundation systems considered for this project included drilled piers, augercast piles, <br />and driven piles. <br />Drilled piers are best suited when weak or compressible, cohesive soils overlie strong, <br />relatively incompressible, cohesive soils. Drilled piers can be designed to develop most <br />of their load carrying capacity from end bearing. These soil conditions do exist on this <br />site, however, headspace limitations and the presence of water-bearing sand makes <br />drilled piers difficult to install at this site. <br />Auyercast piles achieve their load carrying capacity hy a combination of friction along <br />the side of the pile and from end bearing. They are best suited to transmitting loads to <br />dense sancl or gravel above or below the water table. i hey are not well suited in hard <br />Otto Rosenau 8 Associates, Inc. Page 5 ot 13 <br />g%7 <br />