A FlatironDragados-led joint venture has finalized a $691 million contract to deliver an additional water storage and fish passage project on a dam in Ravensdale, Washington, per a Thursday announcement shared from the builder.
FlatironDragados and Toronto-based JV partner Aecon signed the deal with the U.S. Army Corps of Engineers, Seattle District, for the work on the Howard A. Hanson Dam on Washington’s Green River.
The project will employ the integrated design and construction method developed by USACE that brings together the designer of record and contractors early in the design phase through construction. The model improves coordination, mitigates risk and enhances cost and schedule certainty, according to the release from Atlanta-based FlatironDragados.
“In partnership with Aecon, we worked closely with USACE, Tacoma Public Utilities and other stakeholders throughout the collaborative design phase,” FlatironDragados COO Richard Grabinski said in the release. “As we advance to construction, we will continue that approach through the IDaC delivery model that will enable ongoing coordination, proactive risk mitigation and safe, efficient project delivery for the Green River watershed.”
The collaborative design phase has concluded, which means the project is advancing into construction of the enhanced fish passage, ecosystem restoration, water supply reliability and flood risk reduction.
The dam is located about 35 miles southeast of downtown Seattle. The JV will construct a passage for juvenile out-migrating salmon to bypass the existing dam while mitigating flood risk in the region.
The facility will include a fixed multiport collector, steep slope bypass, deceleration tunnel and outfall stilling basin structures.
“This project significantly expands our water storage, ensuring a reliable supply for thousands of homes and supporting the future economic growth of the region, while also providing salmon access to nearly half of the Green River habitat above the dam,” USACE Seattle District Commander Col. Kathryn Sanborn said in the release.
Construction is slated to begin in the second quarter of 2026.
