Dungeness River Bridge and Floodplain Restoration Sequim, Washington

Once constrained by by a 585-foot-long railroad bridge, the Dungeness River floodplain was restored while reusing that existing trestle structure to design its river-worthy, salmon-friendly replacement. Located on the Dungeness River at Railroad Bridge Park in Sequim, this multifaceted project supports Olympic Discovery Trail and the broader redevelopment of the Dungeness River Nature Center.

Working with a Local Tribe to Repurpose a Bridge, Reconnect a Floodplain, and Enhance Aquatic Habitats

The restoration and structural design was accomplished in coordination with the Jamestown S’Klallam Tribe with the goal of redesigning multiple features that constrained the floodplain process. Along with the railroad trestle, a parking lot would also be replaced with 350 feet of side-channel and log revetments. Along with levee setbacks, these improvements enhance the local salmonid rearing and spawning habitat. A unique no-rise analysis including two-dimensional hydraulic modeling and large wood stability calculations was used for the dynamic river setting. In utilizing the existing railroad bridge, a unique wishbone approach connects the trails and nature center. From preliminary to final design and preferred alternatives, the Otak team prepared each step of the process including permitting, technical specifications, costs, and bid documentation.