Last Friday, the American Council of Engineering Companies of Washington (ACEC WA) recognized the Padden Creek Fish-Passage Design-Build with a Silver Best in State Award. The award was presented at the chapter’s annual Engineering Excellence Awards Dinner, where a group of GeoEngineers staff was on hand to celebrate. Padden Creek is one of GeoEngineers’ most recent fish-passage projects for the Washington State Department of Transportation (WSDOT), and it came with plenty of challenges.
Padden Creek runs from Lake Padden just outside Bellingham, Washington, west through town to empty into Bellingham Bay. Historically, the creek supported runs of salmon and steelhead, but the culverts conveying the creek beneath SR 11 and I-5 prevented fish from accessing quality upstream habitat. GeoEngineers joined a design-build team with friends at KPFF Consulting Engineers and Granite Construction to compete for and then complete the project.
The Washington State Department of Transportation (WSDOT) faced a unique challenge; build a sustainable fish habitat beneath an active interstate and near a busy intersection—and do it with minimal traffic disruptions. The team used innovative design and accelerated construction techniques to build 1,000 feet of new stream channel with more than 100 habitat features, two fish-friendly culverts and two bridges that restored fish passage under SR 11 and I-5 and provide access to more than five miles of upstream rearing and spawning habitat.
The team used a combination of creative top-down construction sequencing and innovative engineering to decrease the total number of traffic impact days on I-5 from 400 to just 225 and built the entire southbound bridge in just 37 days. They overcame complex geotechnical conditions, construction obstructions, and unexpected changes to regulatory policy to successfully replace the old crossing with two full-span bridges for north and southbound I-5 and a 53-foot-wide buried arch at an adjacent street.
The Padden Creek crossing at SR 11 is in a congested area, adjacent to a busy intersection, a senior living facility, and several businesses. The project team listened to community concerns and worked with the city to develop modified detour plans for both traffic and pedestrians that would allow full-time and direct access to businesses. The team minimized road closures once again by building the 20-foot by 8-foot culvert during a single weekend closure of SR 11, ultimately completing the entire culvert and reopening the road in just 52 hours.
The project team also added habitat-enhancing features that will evolve with the stream system over time. At the SR 11 crossing, the team shifted the stream alignment from the conceptual design location to create an entirely new off-channel habitat for fish. Stream engineers also placed large woody material (LWM) like fallen trees and root wads throughout the project reach according to a complex matrix, providing essential habitat for young fish.
Within two weeks of finishing construction at the SR 11 site, salmon, steelhead and other fish were observed swimming and spawning throughout the restored Padden Creek reach, demonstrating the immediate success of the stream crossing and environmental features.
The GeoEngineers team helped WSDOT replace the two fish barrier culverts beneath I-5 and SR 11 with four fish-passable structures, and they did it with minimal traffic disruptions. The project’s success depended on close collaboration and trust between teaming partners, WSDOT, and regulatory agencies—and WDFW is already using it as an ideal example of a fish-passage project that delivered effective habitat enhancement on time and on budget.