Lake_Youngs-Basin_Hydrogeology_Technical_Memo_1998.pdf

This file is a technical memorandum on Lake Youngs Basin hydrogeology prepared in 1998, relevant to Seattle Public Utilities' upcoming design and infrastructure projects at the Lake Youngs facility in unincorporated King County, Washington. The memorandum provides hydrogeological analysis and technical background supporting two forthcoming consultant solicitations: 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. An outreach event and facility tour is scheduled for October 22, 2026, from 10 a.m. to 1 p.m. at the Cascade Dam facility to brief potential consultants on the project scopes, site history, and functional overview. No formal proposal deadline, contract value, contract term, or procurement timeline is stated in the associated outreach notice, as the tour functions as a pre-bid informational session prior to formal RFP issuance.

The technical memorandum serves as supporting documentation for the project scope and alternatives analysis, with topographic and infrastructure mapping based on State Plane coordinates (NAD83-91, Washington North Zone). The file includes reference to a previously rehabilitated Cured-in-Place Pipe section within the drainage system and an Options Analysis Study Report. No pricing terms, set-asides, funding amounts, or other financial details are specified in the associated outreach documentation, indicating that such information will be included in the formal solicitation materials to be issued following the October 2026 informational event.