2410 RAILWAY AVE Geotech Report 2023-04-06

Penske Truck Leasing-Proposed Service Facility,2410 Railway Ave, Everett,WA Mar.8,2019/Rev.Feb. 25,2020 Geotechnical Engineering Report P1493-T18 settlements between comparably loaded piles are not expected to exceed about 50 percent of this value. The pile capacities provided above apply to single piles. If piles within groups are spaced at least three pile diameters on center, no reduction for pile group action need be made. The structural characteristics of the pile materials and allowable internal stresses may impose more stringent limitations and should be evaluated by the structural engineer. Lateral loadings due to wind or seismic forces can be resisted by uplift or lateral loading on the piles,or lateral soil resistance of the pile cap. The manner in which these loads are transferred into the piles will be a function of the design of the foundation system. Passive soil resistance of the pile cap may be computed using an equivalent fluid density of 220 pcf(pounds per cubic foot)for a level backfill surface, provided the backfill around the pile cap is compacted to at least 95 percent of maximum dry density American Society for Testing and Materials (ASTM) D-1557. This value incorporates a factor of safety of about 1.5. Lateral capacities for augercast piling are dependent upon the characteristics of the reinforcing steel and the coefficient of subgrade reaction for the surrounding soils. We recommend that the pile stiffness T be computed using the formula T=(EI/f)1'5 where E equals the pile modulus of elasticity, I equals the pile moment of inertia,and f equals the soil coefficient of subgrade reaction. A value of 10 tcf(tons per cubic foot)should be used for f. For the recommended penetration, the maximum moment for piles fixed against rotation at the ground surface will occur at a depth equal to about 1.8 T and the magnitude of this moment,M, can be computed using the formula M=0.25 P T where P is the lateral force applied at the ground surface. The moment will decrease to zero at a depth of about 4.5 T. The maximum pile deflection at the ground surface can be computed using the formula D=0.93 (PT3/EI). Pile Installation: Augercast cast-in- lace concretepiles should be installed usinga continuous- flight, g (cast-in-place)) hollow-stem auger. As is common practice,the pile grout would be pumped under pressure through the hollow-stem as the auger is withdrawn. Reinforcing steel for bending and uplift would be placed in the fresh grout column immediately after withdrawal of the auger. No direct information regarding the capacity of augercast piles (e.g., driving resistance data) is obtained while this type of pile is being installed. Therefore, it is particularly important that the installation of augercast piles be carefully monitored by a qualified individual working under the direct supervision of a geotechnical engineer. It should be noted that the recommended pile penetration and allowable capacities presented above assumed uniform soil conditions. There may be unexpected variations in the depth to and characteristics of the supporting soils across the site. Accordingly,we recommend that pile installation be monitored by a member of our staff who will observe installation procedures and evaluate the adequacy of individual pile installations. Migizi Group, Inc. Page 12 of 17 il'li