OLYMPIA – Thurston County Public Works’ August bridge installation over Beaver Creek, along Beaver Creek Road, drew national attention as a test case for construction activities within endangered species habitat. It also provided a cost-effective way to replace some of the aging culverts in the county.
Replacing the aged and failing culvert with a new bridge had more than a few logistical issues. Breeding seasons for coho salmon, and other native fish, limit in-water construction work to a window between June and mid-September. The muddy area surrounding Beaver Creek is habitat for the Oregon Spotted Frog, an endangered species protected under state and federal regulations.
Working in such an environmentally-sensitive area required multiple permit approvals and close coordination with several state and federal agencies. The presence of endangered species also meant construction crews had a limited timeframe and limited space to accommodate construction activities. Through strategic planning and coordination with the Washington Department of Fish and Wildlife, U.S. Fish and Wildlife, and the U.S. Army Corps of Engineers, county crews minimized construction impacts to sensitive species as well as residents using the roadway.
Beaver Creek Road, a narrow two-lane roadway located near Maytown off Interstate 5, exit 95, is the only access route for local residents and the corridor where power and communication cable lines are located. Power lines had to be taken down to accommodate construction equipment, and communication utilities, such as internet and phone, were interrupted twice during the bridge installation. Because none of the creek banks could be used, construction equipment had to be staged along Beaver Creek Road and residents experienced some travel delays during the heaviest periods of construction.
Yet, despite the logistical issues, the project was successfully completed in less than one month, with minimal residential and traffic disruptions.
“We worked hard to make sure that every part of this project was tightly-organized and highly-coordinated,” said Matt Unzelman, Project Manager and Senior Civil Engineer for Thurston County Public Works. “This project not only shows that construction activities can be successfully accomplished in highly-sensitive habitat areas, but these bridges can reduce construction delays because they can be installed quickly and more efficiently than traditional methods. We know projects like this can be a big disruption to the community, so we really appreciate the resident’s patience during some of the long delays they experienced.”
The new bridge installed over Beaver Creek was pre-fabricated – meaning the bridge was constructed off-site then delivered in-tact and installed using a crane. This new method of bridge installation can reduce bridge construction costs by nearly one-half. This could save the county $200,000 to $400,000 per project for similar bridge replacements in the future.
“As our roads, bridges and culverts age, they require more and more maintenance each year just to keep them in a safe condition. But, eventually, they need to be replaced,” says Scott Lindblom, the Interim Director of Thurston County Public Works. “The culvert on Beaver Creek Road had rusted completely through and was beyond repair. In this case, a pre-fabricated bridge proved to be a great way for us to save time and money, while minimizing impacts on the community.”
To receive updates on Thurston County road construction projects, follow @Thurston_PW on Twitter or visit co.thurstoncounty.wa.us/publicworks.