5801 S 2ND AVE B 2024-11-07 - Laserfiche WebLink

Geotechnical Engineering Evaluation Lyashenko Accessory Dwelling Unit Development 5801 South 2nd Avenue Everett, Washington INTRODUCTION This report presents the results of our geotechnical engineering investigation and evaluation of the planned Lyashenko ADU development project in Everett, Washington. The project site is located at 5801 South 2"d Avenue, as shown on the Vicinity Map in Figure 1. The purpose of this study is to explore and characterize the site's surface and subsurface conditions and to provide geotechnical recommendations for the planned site development. The site is currently occupied by an existing single-family residence within the central portion of the property. Final development and grading plans have not been prepared at the time this report was issued. However, we understand that the ADU will most likely be developed in the north -central to northeastern portions of the property. Final stormwater plans have also not been developed, however, we understand that stormwater may be directed to on -site infiltration systems, if feasible. The existing site layout is shown on the Site Plan in Figure 2. SCOPE The purpose of this study is to explore and characterize the site surface and subsurface conditions, and provide general recommendations for site development. Specifically, our scope of services included the following: 1. Reviewing available soil and geologic maps of the area. 2. Exploring the subsurface soil and groundwater conditions within the site using a track - mounted excavator. NGA provided the trackhoe. 3. Providing long-term design infiltration rates based on one on -site Small -Scale Pilot infiltration Test (PIT), if feasible within the site. PIT to be performed in accordance with the 2016 Snohomish County Drainage Manual. Water was provided by the client. 4. Providing recommendations for earthwork and foundations. 5. Providing recommendations for temporary and permanent slopes. 6. Providing recommendations for slab and pavement subgrade preparation. 7. Providing recommendations for site drainage and erosion control. 8. Determining feasibility of on -site storm water infiltration. 9. Documenting the results of our findings, conclusions, and recommendations in a written geotechnical report. NELSON GEOTECWNICAL ASSOCIATES, INC.