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Submitting Firm: Otak
Location: Clark County, Washington
Client/Owner: Clark County
Other Consultants/Key Participants: GRI, Lee Contractors, SWCA Environmental Consultants

The Manley Road and Stream Improvements Project is a mile-long roadway safety improvement project on a rural county road. The project area included a complex stream enhancement design with the replacement of four fish barrier culverts.

The roadway design included adjusting the horizontal and vertical alignment of the roadway to improve steep grades, sharp curves, and short sight distances. The design and construction phasing took into account an operating quarry that is located within the project area that required relatively heavy truck access. The culvert replacements varied in complexity from steep (12 percent) slopes and large drops to much flatter areas prone to deposition and frequent flooding. The stream parallels the road through the middle portion of the project and was pinned up against the 20-foot road embankment.

The project restored fish passage and stabilized the streambanks through bottomless culverts, detailed cascade-pool channel design, and bioengineered bank stabilization techniques.

The project required a large team of many disciplines including surveyors, biologists, geomorphologists, structural engineers, transportation engineers, hydraulic engineers, construction inspectors and contractors.

鈥淥TAK has been quick to respond to issues throughout construction. During a storm event in January 2021, heavy rainfall coupled with a plugged culvert upstream of our work led to that culvert washing out. 鈥� OTAK quickly arrived onsite to assess the damage and make recommendations on how to address the issues the storm created,鈥� wrote Brad Fisher, PE, Clark County Public Works project engineer, when recommending the project for ACEC recognition. 鈥淏udget was becoming an issue in the second season of work on this project. OTAK ensured that we covered the necessary work 鈥� and that we came in on budget.鈥�