Final_DelineationReport_CascadeDam_020619.pdf

This is a Final Delineation Report for Cascade Dam prepared by Seattle Public Utilities, a municipal utility serving the Seattle metropolitan area in Washington State. The report documents the delineation and technical specifications of the Cascade Dam facility and associated infrastructure at Lake Youngs in unincorporated King County, Washington. The document supports two upcoming design contracting opportunities: Cascades Dam and Perimeter Dike Design, and Lake Youngs Perimeter Drain Lining. The Lake Youngs Perimeter Drain Lining project encompasses approximately 26,000 linear feet of drainage infrastructure, including vitrified clay pipe and concrete drain lines ranging from 8 inches to 24 inches in diameter (predominantly 18-inch pipe), 37 numbered manholes, and four outfalls. The drainage network is mapped using State Plane coordinates (NAD83-91, Washington North Zone). An informational tour of the Cascade Dam facility was scheduled for October 22, 2026, from 10 a.m. to 1 p.m. to brief potential consultants on the upcoming design projects; this outreach event served as a pre-bid informational session preceding formal Request for Proposal issuance.

The delineation report provides technical and historical documentation supporting the alternatives analysis for the perimeter drain lining project, with previously rehabilitated Cured-in-Place Pipe sections identified within the existing drainage system. No formal proposal deadline, contract value, contract term, or procurement timeline was established in the outreach notice, as the tour functioned as a pre-solicitation informational event to inform potential bidders and encourage consultant participation prior to formal contracting documents being released. Funding source and procurement procedures would be established in subsequent formal RFP documentation.