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deoTest Services, Inc.—Revision 1 April 10,2020 <br /> Kikuchi Retaining Wall, Everett,Washington Project No.20-0344 <br /> immiNEMi <br /> 1) High and very high/severe risk areas: <br /> a. Slopes greater than fifteen percent in the Qtb, Qw, and Qls geologic units; and <br /> slopes greater than fifteen percent with uncontrolled fill. <br /> b. Slopes greater than forty percent in all other geologic units (not Qtb, Qw, and Qls <br /> or uncontrolled fill). <br /> 2) Medium risk areas: <br /> a. Slopes less than fifteen percent for Qtb, Qw, and Qls geologic units and <br /> uncontrolled fill. <br /> b. Slopes of twenty-five percent to forty percent in all other geologic units. <br /> 3) Any area with all three of the following characteristics: <br /> a. Slopes greater than fifteen percent;and <br /> b. Hillsides intersecting geologic contacts with a relatively permeable sediment <br /> overlying a relatively impermeable sediment of bedrock;and <br /> c. Springs, ground water seepage, or saturated soils. <br /> 4) Any area which has shown movement during the Holocene epoch or which is underlain or <br /> covered by mass wastage debris of that epoch. <br /> 5) Any area potentially unstable as a results of rapid stream incision,stream bank erosion or <br /> undercutting by wave action. <br /> 6) Area of historic failures, including areas of unstable, old, and recent landslide or landslide <br /> debris within a head scarp, and areas exhibiting geomorphological features indicative of <br /> past slope failure, such as hummocky ground, slumps, earthflow, mudflow, etc. <br /> 7) Any area with a slope of forty percent or steeper and with a vertical relief of fifteen or <br /> more feet, except those manmade slopes created under the design and inspection of a <br /> geotechnical professional, or slopes composed of consolidated rock. <br /> 8) Areas that are at risk of landslide due to high seismic hazards. <br /> 9) Areas that are at risk of landslide due to severe erosion hazards. <br /> *Note:the above is a summary of EDC 19.37.080 and not a verbatim presentation of the code. <br /> The slopes on the subject property are approximately 20 to 25 feet in vertical height with <br /> measured gradients that range from approximately 47 to 63 percent (25 to 32 degrees). The <br /> subsurface of the slopes is composed of silty/clayey transitional bed deposits (map unit Qtb). For <br /> 10 <br />