CONTENT EXPIRES: December 31, 2028 King County Wastewater Treatment Division’s M Street Trunk is a reinforced concrete pipeline in Auburn, Washington, conveying untreated wastewater to the South Treatment Plant in Renton. Installed in 1963, the pipeline has deteriorated due to long-term hydrogen sulfide exposure. The rehabilitation effort spans over 13,800 feet and crosses city streets, airport property, and residential neighborhoods – posing significant logistical and permitting challenges. This presentation explores how the Progressive Design-Build (PDB) delivery method helped the project team recover lost time and advance construction. Chosen for its flexibility and collaborative nature, PDB proved critical amid setbacks including key personnel changes, incomplete design deliverables, ADA-related permitting issues, and a scope change near the airport that delayed Phase 2. By applying “Design-Build Done Right” principles, the County and PDB team fostered trust, streamlined workflows, and built a cohesive team. Recognizing the tight timeline, the project was split into two packages, enabling early progress during the first seasonal construction window. Package 1 design was completed in July 2025, with construction underway as of September. This presentation will share lessons learned around transparency, role ownership, and real-time decision-making, and demonstrate how PDB’s adaptability helped deliver a solution for a critical piece of infrastructure.