3322 KROMER AVE Geotech Report 2023-05-25

deoTest Services, Inc.—Revision 1 April 10,2020 Kikuchi Retaining Wall, Everett,Washington Project No. 20-0344 nommion these reasons, it is GeoTest's opinion that the subject property meets the requirements of Criteria 1 and 2 above and can be considered to have a medium to high risk of landslide potential. It is, however, GeoTest's opinion that an engineered wall replacement will not adversely create additional hazard to the subject slopes on the property or surrounding properties and will improve the overall stability of the slopes. Stated differently, an engineered wall will mitigate the hazard that already exists on the property. Please note that the Pacific Northwest is seismically active, and it is difficult to predict how the slope(s) at the subject site may behave during a large earthquake. Erosion Hazard Areas Erosion is defined by EMC as "the process whereby the landform is worn away by the action of water, wind, rain or ice activity". An Erosion Hazard Area includes: 1) Areas of the city with slopes of twenty-five percent and greater in Qva and Qal geologic units; exposed slopes of greater than twenty-five percent in other geologic units; and drainage areas which receive stormwater discharge. Based on the information presented above, the mapped soils on the subject property present a low to medium hazard for sheet and rill erosion. As such, it is GeoTest's opinion that the site soils do not meet the definition of an erosion hazard per EMC. Based on the topography of the site and the observed slope inclinations, we still recommend that mitigations be included to reduce the potential for soil to sheet and rill erosion during periods of wet weather. Erosion Hazard Mitigations Based on EMC, the steep slopes located on the property are not considered an Erosion Hazard. GeoTest still recommends that the following mitigations be implemented to prevent excessive erosion from occurring: • All clearing and grading activities will need to incorporate Best Management Practices (BMPs)for erosion control in compliance with current City of Everett codes and standards. • GeoTest recommends that appropriate silt fencing be incorporated into the construction plan for erosion control. • Removal of vegetation and trees without proper mitigation may increase the risk of failure for the surficial soils during periods of wet weather. Planting additional soil-covering vegetation within the subject site and in areas disturbed by excavation activities will help maintain near surface slope stability by providing a stable root base within the near surface soils. • Yard waste should not bedumped onto tho top or face of existing or develo ped site 11