5001 23RD AVE W Geotech Report 2022-10-25

• All Materials: Hot dip galvanized conforming to ASTM A153 and manufacturers specifications for materials. For example, refer to Bulletin 01-9601 if Chance anchors are used. • All helical piles should be designed for adequate lateral stability by the project structural engineer. Unless the owner is willing to assume the risk for potential soil creep (extremely slow possible lateral soil movement due to excessive rains or unusual moisture conditions), it may also be necessary to design the pier foundation for lateral loads from possible soil creep in upper 4-6 feet due to the presence of loose soils and site topography. • All axially loaded piers should have a minimum center-to-center spacing of at least three pier diameters (3D). All laterally loaded piers should have a minimum center-to-center spacing of at least six pier diameters (6D) in the direction parallel to pier loading, and 2.5 diameters (2.5D) in the direction perpendicular to pier loading. Piers placed closer than these values should be designed using the appropriate reduction factors to account for group action. For the final design, the exact geometry of the pier group should be submitted to us for review and approval so that appropriate modifications can be made to our recommendations. • Adequate lateral anchoring or A-framing must be provided for assuring adequate lateral stability as per the structural design. We recommend at least 5 feet of lateral loading due to possible soil movement or soil creep. At your request, we can review and approve the lateral stability analysis performed by others. • Assuming that the pier length to diameter ratio (UD)will be greater than 7, in our opinion, the Matlock and Reese method of analysis can be used for lateral load analyses. Therefore, the lateral soil-structure interaction of single shafts may be analyzed using the software application, LPILE developed by Ensoft, Inc (or equivalent such as COM624). This analysis procedure estimates the lateral load-displacement behavior based on elastic beam-column theory and soil reaction-displacement (p-y) curves. Deflection, bending moment and shear profiles at specified intervals along the length of the shaft are computed. • Resistance to lateral load in upper 5 feet should be neglected. • As noted earlier, all laterally loaded piers should have a minimum center-to-center spacing of at least six pier diameters (6D) in the direction parallel to pier loading, and 2.5 diameters (2.5D) in the direction perpendicular to pier loading. Piers placed closer than these values should be designed using the appropriate reduction factors to account for group action. For the final design, the exact geometry of the pier group should be submitted to us for review and approval so that appropriate modifications can be made to our recommendations.Total lateral load versus deflection graph for the pier group can be developed by adding the lateral load resistance of piers at selected deflections. \ '3Project No: 0314-WA19 August 07,2019 Page No:9-ef42