1910 MERRILL CREEK PKY 2018-11-15

Intracorp E-3592-520 September 23, 1998 Page 7 There are three potential geologic hazards associated with a strong motion seismic event at this site: ground rupture, liquefactian, and ground motion response. Ground Rupture: The strongest earthquakes in the Puget Lowland are widespread, subcrustal events, ranging in depth from thirty (301 to fifty-five (55) miles. Surface faulting from these deep events has not been documented to date. Therefore, it is our opinion, that the risk of graund rupture during a strong motion seismic event is negligible. Liauefaction: Liquefaction is a phenomenon in which soils lose all shear strength for short periods of time during an earthquake. Groundshaking of sufficient duration resuits in the loss of grain-to-grain contact and rapid increase in pore water pressure, causing the soil to behave as a fluid. To have a 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. The effects of liquefaction may be large total and/or differential settlement for structures founded in the liquefying soils. In our opinion, the dense to very dense soils underlying the site have a negligible liquefaction potential. Ground Motion Response: The 1997 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 soil profile type Sp, Stiff Soil as defined in Table 16-J should be used to characterize the site soils. Excavations and Slopes The following information is provided solely as a service to our client. Under no circumstances should this information be interpreted to mean that ECI is assuming responsibility for construction site safety or the contractor's activities; such responsibility is not being implied and should not be inferred. ln no case should excavation slopes be greater than the limits specified in local, state and Federal safety regulations. Based on the information obtained from our field exploration, the site soils expected to be encountered in excavations would be classified as Type C by OSHA. As such, temporary cuts greater than four feet in height should be sloped at an inclination no steeper than 1.5H:'1 V. If slopes of this inclination or flatter cannot be constructed, temporary shoring may be necessary. This sharing will help protect against slope or excavation collapse, and will provide protection to workers in the excavation. If temporary shoring is required, we will be available to provide shoring design criteria, if requested. Earth Consultante, Inc.