1311 W MUKILTEO BLVD 2022-06-29 - Laserfiche WebLink

Geotechnical Engineering Evaluate • NGA File No. 1295621 Tsang Slope Restoration October 21,2021 Everett,Washington Page 5 1 p We should note that the surficial soils encountered on this site are considered moisture-sensitive and may disturb easily when wet. To lessen the potential impacts of construction, we recommend that all restoration activities on the slope take place during dry periods, if possible. Under no circumstances should water be allowed to flow over or concentrate on the site slopes,both during restoration and after restoration has been completed. Erosion Control and Slope Protection Measures The erosion hazard for the on-site soils is interpreted to be moderate but actual hazard will be dependent on how the site is graded and how water is allowed to concentrate. Best Management Practices(BMPs) should be used to control erosion. Areas disturbed during restoration activities should be protected from erosion. Erosion control measures may include diverting surface water away from the stripped or disturbed areas. Silt fences and/or straw wattles should be installed to prevent muddy water from leaving the site or flowing over the slopes or to neighboring properties until vegetation can become established. Stockpiles should not be allowed on site. Disturbed areas should be planted as soon as practical,and the vegetation should be maintained until it is established. The erosion potential for areas not stripped of vegetation should be low. Protection of the sloping areas should be performed as required by the City of Everett. Specifically, we recommend that the slope not be disturbed or modified through placement of any fill or removal of the existing vegetation. Vegetation should not be cut down or removed from slopes unless a mitigation plan is developed, such as the replacement of vegetation for erosion protection. Vegetation should not be removed from the slopes. Replacement of vegetation should be performed in accordance with recommendations of a geotechnical professional. Any proposed development within the steep slope area, including grading or retaining wall development should be the subject of a specific geotechnical evaluation. In areas that are disturbed during or after regrading and restoration,planting,hydro seeding,and/or straw mulching are effective ways to minimize erosion and allow vegetation to be re-established rapidly. Temporary and Permanent Slopes The following information is provided solely for the benefit of the owner and other design consultants and should not be construed to imply that Nelson Geotechnical Associates, Inc. assumes responsibility for job site safety. Job site safety is the sole responsibility of the project contractor. NELSON GEOTECHNICAL ASSOCIATES, INC.