Carey Creek Culvert Replacement

The existing culvert where 276h Ave SE crosses Carey Creek in King County, WA, is undersized and creates a barrier to fish passage and disrupts the passage of sediment and wood. King County retained KPFF Consulting Engineering to complete preliminary design for a replacement crossing.  

KPFF retained WSE to provide hydraulic and geomorphic engineering support.  WSE was tasked with using a 2D HEC-RAS hydraulic model to evaluate the hydraulic performance of the existing bridge and three bridge and channel alternatives. WSE also completed a geomorphic investigation to evaluate sediment and wood delivery to the site and to support bridge design for sediment and wood passage.

Role/Services: 

• 2D HEC-RAS hydraulic modeling for a variety of existing and proposed bridge and
  channel configurations.
• Geomorphic investigation to identify sustainable waterway width and assess wood and
  sediment transport influences, and channel migration and avulsion potential to support bridge design. 
• Scour evaluation and calculations
• Recommended crossing and channel dimensions as well as scour countermeasures.

Outcome: WSE provided recommendations for bridge sizing, scour, scour countermeasures, channel layout, bridge and roadway protection, and large wood conceptual design to support permit applications. The project is moving into 60% design.