1001 14TH ST 2024-03-01 - Laserfiche WebLink

3. PROJECT DESCRIPTION 3.1. EXISTING CONDITIONS Pre -developed conditions of the project site generally consist of existing paved parking and gravel surfacing. The northern half of the project site generally drains to the north towards the Port's North Marina and either discharges directly into the marina via sheetflow or is collected and conveyed via existing underground conveyance systems before discharging to the marina (Snohomish River) through outfalls. The southern half of the project site generally drains to the south towards the Central Marina. Surface water on the southern half of the project site drains to a series of existing catch basins, underground conveyance systems, that are routed through either an existing oil water separator or modular wetland treatment vault before discharging south into the marina (Snohomish River). Refer to Figure HHR-1 in Appendix C for a figure of the existing site drainage basins. Per the site geotechnical report, the project soil conditions consist of sand, silty sand, and sandy silt, refer to Appendix D for the geotechnical report. Groundwater conditions at the site are known to be tidally influenced. Groundwater is anticipated to be between 3-5 feet below the existing ground surface. 3.2. PROPOSED CONDITIONS The phasing of the WPC project is such that the future roadway construction of Millwright Loop, Sawyer Street, Woonerf Street and Central Marina Parking lots within the WPC development will provide the new stormwater conveyance and treatment systems in compliance with the 2019 SWMMWW. Refer to Appendix A for the MWL-PH1 project construction plans. The finished condition after the MWL-PH1 project is represent an interim condition for the Waterfront Place Central project. The project includes site prep, demolition, and preload settlement mitigation for segments of Millwright Loop North and South, and the Chamfer Woonerf. Additionally, the project includes construction of new temporary access road segments which allow the Port to maintain maintaining emergency access along the 14t', Street bulkhead and parking lots. The phasing is planned to minimize impacts to marina tenants and the public who will still have access upland parking site. A description of the proposed interim conditions are as follows: Project Area A consists of the construction of a new temporary access road which consists of 9,029 square feet of asphalt to provide emergency and public vehicular access around the Port. Additionally, this project area includes the widening of an existing pedestrian path which extents from the Port's Waterfront Center to the Weyerhaueser building. This path construction includes 3,310 square feet of new asphalt, and the grinding and replacement of 5,696 square feet of asphalt. Project Area A will be graded to maintain the existing surface drainage to the extent feasible. The new road will be graded to discharge to a biofiltration swale along the southern roadway shoulder to provide basic treatment. The roadway is planned to be removed once future Millwright Loop North is constructed. At Project Area B, 92,681 square feet of asphalt will be removed to facilitate wick drain installation and surcharge fill import and placement along segments of Millwright Loop North and South and the Chamfer Woonerf. To account for future predicted sea level rise the WPC project will raise existing grades between 2 to 6 feet. The scope of this MWL-PH1 project involves importing the required roadway fill and surcharge material for static settlement mitigation within the proposed roadway prisms. Future project phases will include construction of new buried utilities and roadway finishes. 7IF117