1920 GRAND AVE 2016-01-01 MF Import

• I GEOTECHNICAL ENGINEERING S i UDY 1920 Grand c/o Stuchell Enterprises E-9466 December 21, 2000 Page 10 Therefore, if slab moisture is a concern, tne siab should be provided with a minimum of four inches of free-draining sand or gravel. Ir� areas where slab moisture is undesirable, a ! vapor barrier such as a 6-mil plastic membrane may be placed beneath the slab. Two t inches of damp sand may be placed over the membrane for protection during construction and to aid in curing of the concrete. Seismic Desian Considerations The Puget Lowiand is classifie:: ss s S2ismic �one 5 in the 1997 Uniform Building Code (UBC1. Earthquakes occur in the Puget Lowiand with regularity, however, the majority of these events are of such low magnitude they are not detected without instruments. Large earthquakes do occur, as indicated by the 1949, 7.1 magnitude earthquake in the Olympia area and the 1965, E.5 magnitude earthquake in the Midway area. 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: The strongest earthquakes in the Puget Lowland are widespread, subcrustal events, ranging in depth from thirry f30) 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 rupture during a strong motion seismic event is negligible. Liquefaction: Liquefaction is a phenomenon in which soils lose all shear strength for ' short periods of time during an earthquake. 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. 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 tabie; and it must be subject L 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. I ' Based on the density and gradation of the site scils, it is our opinion the potential for �= liquefaction over the site during a seismic event is negligible. � Ground Motion Response: In accordance with Table 16-J of the 1997 UBC, soil type S� ` should be used in design. f � ` � E�rth Conwdtann, Inc. I� V L