A combination of river flow regulation and human manipulation of natural levee formations had resulted in the disconnection of the Sturgeon Lake floodplain, on Sauvie Island, from the Columbia River.Working with CREST (client) and HDR (bridge designer) W2r led this project to replace two undersized culverts with a 96-foot bridge over Dairy Creek and reconnect the Columbia River through the creek to Sturgeon Lake.W2r’s management of the project and design ideas reduced construction costs by over $4M from a prior design proposal.
W2r’s role included managing the consultant team, analyzing hydraulic patterns to develop a stable channel and provide inlet protection, designing bridge scour protection, and designing stream and floodplain habitat enhancements.
Analyses supported a bridge design variance (low chord clearance deficiency) due to the relatively low-lying Reeder Road (levee), and minimizing debris and sediment accumulation at the Dairy Creek mouth was a key component of the restoration.
The design also included several features to meet landowner and habitat requirements including irrigation withdrawals, bank scour protection, low-flow connectivity, and fish passage. Scour countermeasures (bioengineered natural rock toe with willows/habitat logs) met habitat and stability objective to satisfy both County and BPA HIP reviews.
