6700 HARDESON RD BASE FILE 2018-01-01 MF Import

� r� Intracorp July 16, 19.i8 E-3592-620 Pape 7 There are three potential geologic hazards associated with a strong motion seismic avent at this site: ground rupture, liquefaction, and ground motion response. Ground Rupture: The strongest earthquakes in the Puyet Lowland ara wideapread, subcrustal events, ranging in depth f�om thirty (30) to fifty-five (55) miles. Surface faulting from these deep events has not been documented to date. Therefore, it is aur opinion that the risk of ground rupture at this site during a strang motion seismic event is negligible. Liquafactfun: Liquefaction is a phenomenon in which soils lose all shear strength for ahort 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, causinfl the soil to behave as a fluid. To have a potential for liquefaction, a soil must be cohesioniess with a prain size distribution of a specified range (generally sand and silt); it must be loose; 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 potential for liquefaction induced settlement for the flll being used to achieve constructian subgrade elevations should be negligible. Ground Motion Rasponse: The 1997 UBC Earthquake regulatio�s 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 So, Stiff Soil as dafined in Tabie 16-J should be used to characterize the site soils. �e Preoaration and General Earthwork The site is approximately at construction subgrade elevattons. We anticipata futura earthwork operations will primarily consist of flnal grading the build(ng areas, axcavattrfl for foundations and excavating underground utilities. In areas where buildings or pavements are to be constructed and where structural fill is to be placed, the existing light vegetation covering the site should be removed. E.nn co�.w�.,h. �nc.