5010 SOUND AVE 2018-01-02 MF Import

Svrordslrum Residence Geological Assessment Report 5010 Sound Avenue. F-rerca, Washington An approximate 15 feet tall, steep slope is located along the west property line. The slope is on the order of 45 degrees or steeper. Portions of the slope have a rockery along the base. There were no visual indications of instability or ground water emergence on this slope face. This slope is located more than 75 feet from the nearest planned construction on the site. Mappings According to the City of Everett, Landslide Hazard, Critical Areas Map 2, the site is located Within an area of medium landslide hazard. The steep slope area ^.long the western property line is listed as scry high landslide hazard risk based on the steepness of the slope and the underlying geology. As slated ribove, this approximate 15 loot high slope did not have any visual indications of instability or emergent ground water and is located more than 75 feet away from any plar,~^d construction. According to the Distribution and Description of Geologic Unite in the Alukilleo Quadrangle, lVashinglan, h),.latnes 1' Mimtrd, /982, Department of the Interior, llniled States Geological Survev, Miscellaneous Nield,Sludies, Map H -1d38, the project site and surrounding vicinity is underlain by Vashon age to pre-Vashon age transitional beds (Qtb). These sediments consist primarily of thick beds of gray clay, silt and fine to very fine sand. These materials have been glacially consolidated and generally are dense to very dense. I lowever, in some areas these sediments can have a high water and jointing and thus can become unstable in steep slopes. According to the Department of Ecology. Coastal Zones Atlas map of the Everett vicinity, the project site and huniediatcly adjacent properties arc listed as Stable. Seismic Hazards 'file subject site is not located in an identified City of Everett seismic hazard area. However, the site is located very near to the northern portion of the Southern Whidbey Island Paull "Lone. As such, the following inlimnation is provided to aid in the design of the structure. No surficial faulting or earth rupture has been documented, to dale, in the south Everett area. However, the Southern Whidbey Island Paull Zone is being currently studied by the United States Geological Service and has been determined to be active and capable of producing large earthquakes. Much is still to be learned about this fault system but it is generally hypothesized that the recurrence interval is several thousand years. Due to the suspected long recurrence interval and the unknown location ofa fault splay in regards to the project site, the potential for surficial ground rupture is considered to be low during the expected life of the structure. Due to the mapped underlying dense to very dense, glacially consolidated sediments, it is our opinion that the potential risk of damage to the proposed Yirulctures by seismically induced landsliding is low. Cary A. Flo%en, PLLC. 19532 12 ^ Avcnuc NE Shm,linc. Washington 98155-1106 206417-7640