5828 GLENWOOD AVE CINGULAR WIRELESS ANTENNA Geotech Report 2022-10-25 (2)

Adapt Engineering Table 2 Ultimate Skin Friction Capacities Depth(feet) Ultimate Skin Friction(tsf) 0-2 0.0 2-6 0.5 6- 15 0.3 15-30 0.8 30-41.5 1.0 Lateral Capacities: Drilled pier foundations for communication monopole towers are typically rigid and act as a pole, which rotates around a fixed point at depth. Although more complex and detailed analyses are available, either the simplified passive earth pressure method or the subgrade reaction method is typically used to determine the pier diameter and depth required to resist groundline reaction forces and moments. These methods are described below. • Passive Earth Pressure Method: The passive earth pressure method is a simplified approach that is generally used to estimate an allowable lateral load capacity based on soil wedge failure theory. Although the lateral deflection associated with the soil wedge failure may be estimated, design lateral deflections using the passive earth pressure method should be considered approximate, due to the simplified nature of the method. According to the NAVFAC Design Manual 7.02 (1986), a lateral deflection equal to about 0.001 times the pier length would be required to mobilize the allowable passive pressure presented below; higher deflections would mobilize higher passive pressures. The ultimate passive pressure may be taken as the product of the allowable pressure and factor of safety. Our recommended passive earth pressures for the soil layers encountered at this site are presented in Table 3 and do not incorporate a safety factor. These values are expressed as equivalent fluid unit weights, which are to be multiplied by the depth (bgs) to reflect the linear increase within the depth interval of the corresponding soil layer. The passive earth pressures may be assumed to act over an area measuring two pier diameters wide by up to eight pier diameters deep. Table 3 Ultimate Passive Pressures Depth(feet) Ultimate Passive Pressure(pcf) 0-2 0 2-6 250 6- 15 300 15 -30 350 30-41.5 450 AT&T Mobility do General Dynamics October 10,2016 Adapt Project No.WA16-20654-GEO 1"4'age4..