9606 19TH AVE SE McDONALDS Geotech Report 2018-01-02 MF Import

GEOTECHNICAL ENGINEERING STUDY McDonald's Corporation E-6893-1 June 9, 1995 Page 7 Seismic Design Considerations The Puget Sound region is classified as Seismic Zone 3 by the Uniform Building Code (UBC). The largest earthquakes in the Puget Sound region have been subcrustal events, ranging in depth from 30 to 55 miles. Such deep events have exhibited no surface faulting. The UBC earthquake regulations contain a static force procedure and a dynamic force procedure for design base shear calculations. Based on the encountered soil conditions, it is our opinion that a site coefficient of 1.2 should be used for the static force procedure, as outlined in Section 1628 of the 1994 UBC. For the dynamic force procedure outlined in Section 1629 of the 1994 UBC, the curve for Rock and Stiff Soils (soil type 1) should be used on Figure 16-3, Normalized Response Spectra Shapes. Liquefaction is a phenomenon in which soils lose all shear strength for short periods of time during an earthquake. The effects of liquefaction may be large total and/or differential settlement for structures with foundations founded in the liquefying soils. Groundshaking of sufficient duration results in the loss of grain to grain contact and rapid increase in pore water pressure, causing the soil to behave as a fluid for short periods of time. To have potential for liquefaction, a soil must be cohesionless with a grain size distribution of a specified range (generally sands and silt); it must be loose to medium -dense; it must be below the groundwater table; and it must be subject to sufficient magnitude and duration of groundshaking. Based on the subsurface information obtained during our field exploration, it is our opinion that the liquefaction potential at the site is negligible, due to the density of the soils encountered and the absence of a near surface groundwater table. Excavations and Slopes Excavation slopes should in no case be greater than the limits specified in local, state and federal safety regulations. As described in the current Occupational Safety and Health Administration (OSHA) regulations, the dense silty sand in the upper two to five feet would classify as Type "B" and the underlying very dense silty sand would classify as Type "A". Therefore temporary cuts greater than four feet in height, should be sloped at an inclination no steeper than 1 H:1 V in the upper soil layer and no steeper than 0.75H:1 V in the underlying very dense soil. If slopes of this Earth ConauRanta, Inc.