9001 AIRPORT RD SNO ISLE SKILL CTR EXPANSION 2009 Geotech Report 2018-01-02 MF Import

i Subsurfoce Ezploration, Geologic Hazard, a+d � Sno-/sle Skills Center Addition Preliminary Georechnical Engineering Repon Everett, Washington Geologic Hazards and Mitigations f II. GEOLOGIC HAZARDS AND MITIGATIONS IThe following discussion of potential geologic hazards is based on the geologic and ground water conditions as observed and discussed herein. I I 5.0 SLOPE STABILITY ASSESSMENT � There were no significant slopes on the site. Therefore, it is our opinion that the risk of I shallow and deep-seated landslides is low for static and seismic conditions, and no mitigation � measures aze required. I6.0 SEISMIC HAZARDS AND MITIGATION I Earthquakes occur in the Puget Lowland wit6 great regulazity. 1'he vast majoriry of these events aze small, and aze usually not felt. Hc,wever, lazge eatthqualies do occur as evidenced I by the 1949, 7.2-magnitude event; the 1965, 6.5-magnitude event; and the 2001, 6.8- magnitude event. T'he 1949 earthquake appeazs to have been the largest in ihis area during recorded history. Evaluation of return rates indicates that an eazthquake of the magnicude 1 between 6.0 and 7.0 is likely within a given 20- t� 40-yeaz period. Generally, there aze four types of potential geologic hazazds associated with lazge seismic j events: 1) surficial ground rupture, 2) seismically induced landslides, 3) liquefaction, and 4) ground motion. The potential for each of these hazards to adversely impact the proposed project is discussed below. I6.1 Surflcial Ground Rupture I The neazest known and well-studied fault uace to the project site is the Sout6 Whidbey Island- Lake Alice Fault. Data pertaining to the South Whidbey Isla�nd-iake Alice Fault aze not well � documented, but no evidence of surficial ground rupture has br,�n note�. The recurrence intervals for movement along this fault system aze still unknown, althouy,h they are hypothesized to be in excess of sevexal thousand years. Due to the �uspected long � recurrence intervals and the distance to this fault zone, the potential for surficial ground rupture is considered to be low during the expected iife of the structures, and na mitigation I effons beyond complying with the current (2006) International Building Code (IBC) are recommended. � ( lune Il. 2A08 ASSOCG7ED E.1R7Y!SC/ENCES. INC. IEG/W-F.E080313.15-Projms1200907131FE1WP Page 5 $ .'..