Conference Agenda

Clackamas County’s Water Environment Services (WES) has embarked on a project to build one of the largest new outfalls in the Northwest. Once constructed, this project will provide enhanced dilution performance to meet river water quality standards, protect beneficial uses in the Willamette River, and convert the existing outfall for use during peak wet weather events.

Designed to meet projected 2087 buildout flows of 168 mgd combined hydraulic capacity, the project benefited from early contractor input to successfully address challenging design criteria; rigorous permitting requirements; construction risk; and careful sequence of schedule constraints to work concurrently in the water with a nearby bridge widening project led by others.

The new mile-long 90-inch outfall construction requires installation of a 109-inch-diameter tunnel for half of its length in challenging ground conditions with a wet recovery in the Willamette River to install the 18-port 150-ft long diffuser at channel depth. For the remainder of the alignment, the outfall pipeline will be installed in a tight corridor between an old landfill and two of WES’s major 72-inch-diameter pipeline assets that require uninterrupted use during construction.

This presentation will give an overview of how the team successfully navigates construction risks and increasing costs in a volatile market while maintaining the ability to provide design input by using the Progressive Design-Build (PDB) delivery approach. WES also hired an Owner’s Agent to assist in the design/cost review, risk management, and permitting. The PDB contract started in 2022 after careful selection of a qualified Design-Builder, allowing WES to validate the project path forward while refining the construction approach to meet permit requirements and achieve greater cost certainty. The PDB approach has also allowed WES to collaborate more effectively with major stakeholders along the corridor (ODOT, City of Oregon City, multiple regulators) regarding project impacts and opportunities. Finally, WES has been able to gain increased cost certainty with estimates prepared by the Design-Builder that account for well-defined construction risk and contingencies and design opportunities.

More public agencies are considering collaborative delivery to deliver major capital projects for water and wastewater facilities. In 2017, Silicon Valley Clean Water (SVCW), in Redwood City, CA, chose Progressive Design Build (PDB) to deliver all three of the projects making up the $580M SVCW Regional Environmental Sewer Conveyance Upgrade (RESCU) raw wastewater conveyance rehabilitation program. RESCU has stayed on schedule through the pandemic, and is in the commissioning phase concurrently on all three projects, with final completion anticipated by mid-2024. This presentation highlights the importance of Owner involvement in the entire PDB delivery process, from contractor team procurement, through design and construction, to start up and commissioning. Why PDB was selected, how PDB has been implemented over 6 years, and current status will be presented.

RESCU consists of three projects that cover the entire conveyance system:

• Front-of-Plant: new 75-foot deep 80MGD lift station, new headworks with screens and degritting, new 1000LF 63-inch HDPE transmission pipeline to the plant influent;
• Gravity Pipeline: 3.5 miles of 16-ft diameter conveyance tunnel in low strength soils and high groundwater, under a regional airport taxiway and busy residential thoroughfare. Tunnel concrete segment ring excavation support has a finished diameter of 13-ft and is lined with 11-ft diameter fiber reinforced polymer (FRP) raw wastewater conveyance pipe;
• Pump Station Improvements: decommissioned two of four existing conveyance pump stations, rehabilitation of one existing pump station, and replacement of one pump station with a new combined screening facility and wet weather pumping facility.

SVCW leadership championed the early adoption of PDB for wastewater infrastructure, including the first large-diameter wastewater tunnel to be constructed in the US using PDB. RESCU started prior to the Covid pandemic, and, thanks to the effort of the Owner’s program team working remotely using MS Teams (Teams has been used on the Program since mid-2017), and the contractors’ focus on safety, no time was lost through two years of pandemic shutdowns. RESCU is on schedule and within budget expectations, demonstrating the value of Owner involvement in supporting collaborative delivery using PDB.