3301 SEAWAY BLVD Geotech Report 2022-10-25

January 13,2016 Project No.T-7342 The occurrence of interflow will fluctuate seasonally with the highest seepage levels occurring during the normally wet winter to late spring months(October to May). 4.0 GEOLOGIC HAZARDS Section 37.080 of the Everett Municipal Code (EMC) defines geologically hazardous areas,as "areas susceptible to erosion, landslide, seismically induced soil failure,or other geological events." 4.1 Erosion Hazard Areas Section 37.080.A.3 of the EMC defines erosion hazard areas as "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: i, High erosion hazard areas include slopes of 25 to 40 percent in Qva and Qal geologic. units; and slopes of greater than 40 percent in other(not Qva or Qal)geologic units. ii. Very high/severe erosion hazard areas include slopes of greater than 40 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, when they contain debris and mud flows, gullying or rifling, immature vegetation,or no vegetation: i. Slopes of 25 to 40 percent in other(not Qva or Qal)geologic units." The City of Everett Erosion Hazard, Critical Areas Map 3, dated March 2006, shows the eastern margin of the site is within or adjacent a medium to high erosion hazard area. Based on the existing site topography, the site slopes are between 7 and 100 percent. Based on the criteria outlined above, the portions of the site where the slopes are greater than 25 percent would be classified as an erosion hazard by the City of Everett. Section 37.080.C.3 of the EMC allows for development within geologic hazard areas provided the developed will decrease the risk for the hazard. Based on the grading plan provided, it is our opinion that the final development will reduce the potential for erosion at this site. In order to protect the site and surrounding areas during construction,we recommend the following be implemented. Implementation of temporary and permanent Best Management Practices(BMPs) for preventing and controlling erosion will be required and will mitigate the erosion hazard. As a minimum, we recommend implementing the following erosion and sediment control BMPs prior to, during, and immediately following construction activities at the site. Page No. 4