1870 ROSS AVE SEPA 017 - 017 -DAGMAR'S BOAT LAUNCH DREDGE Land Use Decision Documents 2025-04-16

❑ Aquaculture El Culvert ❑ Float ❑ Retaining Wall CIBank Stabilization ❑ Dam /Weir ❑ Floating Home (upland) ❑ Boat House ElDike/ Levee/Jetty ❑ Geotechnical Survey ❑ Road CIBoat Launch ❑ Ditch CILand Clearing ❑ Scientific Measurement Device ❑ Boat Lift ❑ Dock/ Pier ❑ Marina/Moorage ❑ Stairs El Bridge ® Dredging El Mining ❑ Stormwater facility ❑ Bulkhead ❑ Fence ❑ Outfall Structure ❑ Swimming Pool ❑ Buoy ❑ Ferry Terminal ❑ Piling/Dolphin ❑ Utility Line ❑ Channel Modification ❑ Fishway 6e. Describe how you plan to construct each project element checked in 6d. Include specific construction methods and equipment to be used. [heiDi • Identify where each element will occur in relation to the nearest waterbody. • Indicate which activities are within the 100-year floodplain. The boat launch was constructed in 1977 and has not been recently dredged.Approximately 875 cubic yards of material will be dredged over an area of approximately 15,875 square feet(0.34 acre)within the boat launch basin.Sediments will be dewatered within northern portions of the marina,after which disposed of at a licensed facility(Sheets 1 and 2). All sediment removal activities will occur within the existing marina boat launch and not extend into the main channel of the Snohomish River.Sediments to be removed have been deposited over the years by the Snohomish River and have created shoaled areas within the boat launch making it difficult for vessels to launch(Photos 1 and 2). Only the shoaling areas will be removed down to the existing mudline of approximately-3 feet MLLW(Sheets 1 and 2).A silt curtain will be deployed at the end of the existing boat launch floats to minimize turbidity within the main river channel. Sediment removal will occur using a long reach excavator and material will be placed and dewatered on the upland marina,approximately 1,200 feet from the river shoreline before transporting off site to a licensed facility(see figure below).All sediment removal will be undertaken from the boat launch shore. No barge mounted dredging will be conducted.The use of a clam shell bucket dredge will not be necessary to remove sediments. ORIA-16-011 Page 6 of 15