4841 GLENWOOD AVE 2018-01-02 MF Import

( � May 5, 2008 Mr. Ron Riach/JRR Engineering, Inc. L&A Job No. S A043 Page 4 free of orgar�ic and other deleterious substances may be used as swctural fill. The above recommendations are presented in Plate I attached hereto. Design Soil Paramctcrs The proposed precast concrete block wall is up to about 8 to 12 feet tall. We recommend that the walf be designed for a fully draincd condition in accordancc with the following soil perimeters: Reinforced Retained Foundation Leveling Soils Soils Soils Rock IIasc Unit Weight, 7', pcf 130 125 130 130 Angle of Intemal Friction, 36 34 36 40 �, degrees Cohesion, c, psf 0 0 0 0 A uniform surcharge of 200 psf of traffic loading on the access roadway should be wnsidered in the stability analyses for the bloch walL The block wall should be dcsigned for a minimum factor oC 1.5 against sliding failure and 1.7 against overturning failure under the static louding condition. The Pugct Sound region is in an activc seismic zone and the block wall should also be designed under thc seismic loading condition for a 100-year seismic event. The peak ground acceleration is about 0.3g (g = gravity force) for such an event in the Puget Sound region. The block wall, however, are built with intcrlocking concrete blocks with high tlexibility, and the blocks will not movc in unison during earthquakes. Thcrefore, for design of thc block wall under the seismic loading condition, thc ground accelcration may be reduced to 0.2g. The block wall should be designed for a factor of sufery of at least 1.15 against sliding and 1.2 against overturning failures under the seismic loading condition. LIU & ASSOCIATES, INC. ��y