1033 TEMPLE DR 2023-12-29 - Laserfiche WebLink

December 14, 2020 Page 3 of 6 Limited Geologic Evaluation h. Areas that are at risk of landslide due to high seismic hazard. i. Areas that are at risk of landslides or mass movement due to severe erosion hazards. The site does not contain landslide hazards. There are local steep slope hazards (item g) that are a result of prior grading activities (cuts). These areas appear stable at this time. There are steep slope hazards south of the property and on adjacent properties; however, these areas do not pose a threat to the subject property or project. Nor will the project affect the adjacent steep slope areas if constructed per plan and per Wical engineering standards. The site is underlain by till and outwash soils. There is a stockpile of fill soils; however, this pile is covered with plastic and will be used as structural fill behind the new terraced wall system near the east prope line. We did not observe evidence of historic or recent landslide activity or severe erosion on the subject or adjacent properties. There was no evidence of emergent groundwater, soil creep, or permeable soil overl3ing silt and clams 3. Erosion hazard areas: a. Those areas defined as high and very high/severe risk of erosion in the Dames and Moore Methodology for the Inventory, Classification and Designation of Geologically Hazardous Areas, City of Everett, Washington: July 1, 1991, or as revised through best available science: (1) High erosion hazard areas include slopes of twenty-five to forty percent in Qva and Qal geologic units; and slopes of greater than forty percent in other (not Qva or Qal) geologic units. (2) Very high/severe erosion hazard areas include slopes of greater than forty percent in Qva and Qal geologic units. b. Those areas defined as medium risk of erosion in the Dames and Moore Methodology for the Inventory, Classification and Designation of Geologically Hazardous Areas, City of Everett, Washington: July 1, 1991, or as revised through best available science, when they contain debris and mud flows, gullying or rifling, immature vegetation, or no vegetation: (1) Slopes of twenty-five to forty percent in other (not Qva or Qal) geologic units. 4. Other areas which the city has reason to believe are geologically hazardous. The NRCS maps indicate that the western portion of the site is underlain by Alderwood grravelly sandy loam (15 to 30 percent slopes) and the east portion is underlain by Alderwood-Urban land complex (2 to 8 percent slopes). In general, the erosion potential at the site varies from low to very high depending on the slope magnitudes. Severe erosion potentials generally include areas with slopes of 15 percent or more in outwash soils. The near surface soils appear to consist of drift or till and likely have a moderate erosion potential when exposed. Provided proper erosion control measures are implemented until final landscaping is in place, the erosion potential can be maintained at a low level. These include keeping all exposed soils covered when work is not taking place, providing silt fences around the low side of all work areas, and utilizing other systems as needed based on specific conditions. B. Geologically Hazardous Slope Setbacks and Slope Protection. 1. Geotechnical Assessment Requirements. Development proposals on or within two hundred feet of any area designated as or which, based on site -specific field investigation, the city has reason to believe are geologically hazardous areas shall submit a geological assessment as required by subsection F of this section. www.cobaltgeo.com �e (206) 331-1097 r