954 NORTH PARK DR 2023-10-31 - Laserfiche WebLink

GeoTest Services, Inc. September 6, 2019 Proposed Swimming Pool — 954 North Park Drive, Everett, WA Project No. 19-0361 a higher risk of liquefaction; this area consists of embankment fill from construction of the railroad and is not considered a significant risk to the residence or proposed swimming pool. Due to the relatively dense nature of the native soils in the area of development and the absence of near -surface groundwater, it is GTS's opinion that the project site is not considered to be a Seismic Hazard. Thus, GTS concurs with the findings of the Dames and Moore and DNR maps. No special mitigation for liquefaction is recommended. Erosion Hazards EMC Section 19.37.080.A.3 states that erosion hazard.areas are "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." The City of Everett Erosion Hazard Critical Areas Map 3 (Goodwill, 2006) classifies the soils near the top of the on -site slopes as medium risk and the soils along the slope as high risk due to the presence of slopes greater than 40 percent. The steep slopes flanking the existing residence and yard are heavily vegetated and will not be altered as part of the proposed construction, as the proposed pool will be set back away from the slope. The footprint of the proposed swimming pool lies close to the residence in an area of landscape grass, and minimal earthwork is anticipated for this project. Accordingly, the following recommendations are intended to prevent excessive erosion from occurring: • All clearing and grading activities for future pool construction will need to incorporate Best Management Practices (BMPs) for erosion control in compliance with current City of Everett codes and standards. • GTS recommends that appropriate silt fencing be incorporated into the construction plan for erosion control. • GTS recommends that onsite BMPs be implemented during construction. Areas of native vegetation left in place could also be enhanced by adding additional native plant species and/or other vegetation enhancements. • 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 brush and 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 be dumped onto the top or face of existing or developed site slopes. Yard waste can retain water and cause slope instability. 12