4102 RUCKER AVE SAFEWAY FUELING STATION 2016-01-01 MF Import

GEOTECHNICAL ENGINEERING STUDY Inform, Inc May 9, 2002 E-8493-5 Page 8 Footing excavations must be observed by an ECI representative, prior to placing forms or rebar, to verify that soil and groundwater ccnditions are as anticipated in this report. Slab-an-Grade Fbors Slab-on-grade floors may be supported on competent native soils, or on structurai fill. Slab-on-grade floors located in the existing fill areas should be supported on at least one foot of structural rill. Loose or unstable areas encountered at subgrade elevations should be moisture conditioned and recompacted, or overexcavated and replaced with structural fill. The slab-on-grade floor should be provided with a capillary break consisting of a minimum of four inches of free-draining sand or gravel. In areas where slab moisture is undesirable, a vapor barrier such as a 6-mil plastic membrane should be placed beneath the siab. Two inches of damp sand may be placed over the membrane for protection during construction and to aid in curing of the concrete. Seismic Design Consideretions The Puget Lowland is classified as a Seismic Zone 3 in the 1997 Uniform Building Code (UBC). Earthquakes occur in the Puget Lowland with regularity; however, the majority of these events are of such low magnitude they are not felt without instruments. Large earthquakes do occur, as indicated by the 1949, 7•2 magnitude earthquake in the Olympia area, the 1965, 6.5 magnitude earthquake in the Midway area, and the 2001, 6.8 magnitude Nisqually earthquake. There are three potential geologic hazards associated with a strong motion seismic event at this.site: ground rupture, liquefaction, and ground motion response. Ground Rupture: Tha strongest earthquakes occur in the Puget Lowland. These events are widespread, subcrustal events, ranging in depth from thirty (30) 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 ground rupfure at this site during a strong motion seismic event is negligible. Earth Consultanis, Inc.