In addressing the City of Camas immediate needs while providing new piping for future demands, a new pedestrian bridge over the Washougal River was designed to connect a regional trail system and carry a new water main. Otak was chosen to manage a full-service design team addressing water and utility design. That team included civil engineering, trail and landscape architecture, environmental analysis and permitting, structural and geotechnical engineering and archaeological investigation.
A Structure to Connect a Trail System and Carry Utility Infrastructure
Working in an area with archaeologically sensitive sites and important fish habitat would pose a challenge to any single project, yet the City of Camas sought three concurrent projects in just such a space: nearly two miles of a regional trail system, a new 24-inch water transmission main and a new bridge to carry water and sewer over the Washougal River. The full-service design process assessed the site to determine the ideal bridge type while limiting impact to the environment and avoiding disruptions to any culturally-sensitive resources. This effort included river hydraulic analysis and scour design as well as the geotechnical engineering and archaeological investigation. In meeting the active transportation goals of the trail system, landscape architects focused on reviewing trail alignment options, in-field direction of vegetation clearing along the preferred trail route, and construction drawings and specifications.
A decade of stream flow and water quality data collected by the County was used to develop and calibrate hydrologic and water quality models of the 12-square mile Whipple Creek basin. Using future build-out assumptions and BMP effectiveness data, stormwater management options were modeled and developed to meet existing and designated uses.
Hydrologic and Water Quality Models for a Complete Stormwater Plan
After 100 years away, Salmon returned to the Hunter Point Road culvert following its rehabilitation along with the stream it facilitates. Thanks to the investment by Thurston County, Washington, including state grants, a deep ravine and large drop downstream of the Hunter Point Road Culvert to remove a barrier to fish passage.
A Complicated Stream Restoration Design for a Top-Priority Culvert Replacement Project
Thurston County received state grants for culvert replacements, and Hunter Point Road was their highest-priority fish passage project. The project involved a new bridge and complete stream reconstruction. Complications included high road embankments, a single access road (dead end), a stream confluence immediately upstream of the crossing, and the need to provide habitat function to the stream beneath the bridge structure. After consulting with the tribes and the Washington Department of Fish and Wildlife, the team elected to include large woody debris in a variety of configurations along with specific stream bed geometries and materials. During construction, the County fish salvage team relocated approximately 500 fish from the downstream reach, indicating the high potential of future use upstream of the project. Otak structural engineers designed an 80-foot-span bridge to replace the existing four-foot-diameter culvert. Shortly after construction was complete, spawning salmon returned, after almost a century-long absence. The project represents a historic moment, and a tribute to the funding agencies and Thurston County for funding this project and hiring Otak to bring it to fruition.
Once considered the second most hazardous bridge in Oregon, Lommen Bridge in Tillamook County was at risk of collapse during an earthquake or tsunami. Its replacement represents a lasting solution, designed and constructed with a focus on environmental sustainability, for this critical connection to the region’s coast.
A Resilient, Sustainable Bridge Connection to Oregon’s Coast
A new, three-span bridge was constructed next to the existing structure that was cracking and leaning. This allowed traffic to be kept open at all times during the project. The bridge replacement was constructed as one of only two bridges in Oregon to use the latest seismic-resilient technology of lead-rubber seismic isolation bearings. The innovative project solved all of the County’s challenges while coming in under budget and also prioritizing a sustainable approach to local ecology. Otak teams were responsible for the design, construction and environmental science that resulted in the much needed Lommen Bridge replacement.
The Smith Island estuary restoration is one of the largest efforts of its kind. By removing agricultural levees and dikes—thereby reconnecting Union Slough’s historic tidal marshlands—Snohomish County created more than 300 acres of habitat for endangered Puget Sound salmon and secured the long-term well-being of its local farmers, communities, and infrastructure.
Restoring a Wetland to Expand Endangered Species Habitat and Improve Community Infrastructure
Restoration efforts involved close collaboration with a multi-agency coalition of county, state, federal, tribal, and local stakeholders to design, permit, and prepare the construction documents for this large-scale restoration project, located near Interstate 5 outside the city of Everett. The Otak-designed improvements addressed concerns related to interior drainage, saltwater intrusion, and flood protection, as well as the protection of a nearby liquified natural gas pipeline. Specific elements include safe breaching and removal of remnant dikes and agricultural drainage features, along with the installation of drainage pipes and check valves, a stormwater pump station, and a public parking area. The restored estuarial wetlands include five types of tidal channels and four types of wood structures and rock revetment for scour protection.
Willapa Bay is a significant ecological resource with a community dedicated to its restoration and conservation. Through physical investigation, modeling, alternative analysis, and design, tidal inundation to 100 acres of estuary habitat would be restored as well as fish passage to Smith Creek, a tributary to Naselle River and Willapa Bay.
Restoring a Estuary Habitat and Designing a Bridge for Climate Change Resilience
Development and levees on the Naselle River floodplain had kept juvenile salmonids from prime rearing habitat and reduced the tidal flux into Smith Creek. In addition, the crossing at the mouth of Smith Creek is formed by an embankment with two 72-inch culverts with collapsed and failing tide gates. In restoring the natural connection, the gates would be replaced with a 100-foot-span bridge to achieve unconstrained tidal flux, fish passage, and scour designs. A cross levee protects nearby private land and roads. To inform a resilient design, high-magnitude flood models were used to assess conditions resulting from climate change and mapped historical channels in the floodplain to improve salmonid habitat.
Otak carried forward a project at the 60% design phase at the site of the old Boise Cascade Mill on Pringle Creek in Salem, Oregon. Otak designed a new stream channel through this urban reach to restore a more natural stream condition and improve fish passage. We also provided large wood structures for habitat, performed restoration design calculations for bed gradation and channel geometry, and developed construction plans for the site.
Resolving Stream Issues and Fish Passage Constraints
The project was punctuated by a restricted design schedule. Otak moved quickly and used available data to begin design while additional field data was being collected. Through frequent communication with the City of Salem, Otak was able to efficiently deliver a design that met the City’s needs and within the restricted design time frame.
Dedicated to conserving and restoring Tillamook County’s estuaries and watersheds, the Tillamook Estuaries Partnership is a nonprofit organization addressing the critical problems of habitat loss, decreased water quality, sedimentation, and flooding.
A Bridge Designed to Replace a Fish Barrier
In conjunction with Tillamook County Public Works and the Salmon Superhighway Partnership, the county hired Otak to lead design of a fish passage/culvert replacement project on Peterson Creek, a tributary to the Miami River on Oregon’s North Coast. A 60-foot span bridge will replace a six-foot culvert that blocks fish passage upstream, opening up several miles of potential habitat. Since this is an emergency evacuation route, the replacement structure will be constructed in stages to keep traffic and freight moving.
The Mt. Hood Community College Salmon-Safe Clean Water Retrofit project adds low-impact development stormwater improvements to a five-acre, actively used parking lot where runoff from impervious areas had been discharging directly to nearby creeks for decades without treatment or attenuation.
Low-Impact Development for Improved Water Quality and Salmon Habitat
Led by the Sandy River Watershed Council, the project was designed to improve water quality and salmon habitat in Kelly and Beaver Creeks. This voluntary retrofit project features stormwater planters, drywells, a highly visible rain garden, and depaved parking spaces with “Reserved for Salmon” signs in English, Spanish, and Chinook. The Otak team provided engineering design, landscape architecture design, permitting services, public outreach support, and construction administration. The project was made possible by multiple partners including East Multnomah Soil and Water Conservation District, Metro, City of Gresham, Spirit Mountain Community Fund, Depave, and the Oregon Department of Environmental Quality.
After Colorado’s 2013 flood, the state received funding from the Natural Resources Conservation Service Emergency Watershed Protection Program to address extensive damage to homes, businesses, and road infrastructure.
A Reconnected Floodplain and Restored Stream to Mitigate Future Flooding
During the flood, high sediment loading quickly plugged undersized culverts at road crossings and caused threatened life and property. Improvements included floodplain reconnection, restored riffle-pool and step-pool sequencing, offset protection at critical assets, bank stabilization, and native revegetation. Public stakeholder meetings facilitated discussions with property owners, completed 1D and 2D hydraulic modeling, and provided sediment transport analyses to meet technical design and floodplain permitting requirements. This project has made the area much safer for its residents, with resiliency protections, reduced flood risk, and stream health improvements. The river will perform better during future floods with reduced damage and faster recovery time. Working closely with Lefthand Watershed Oversight Group and property owners, Otak led the analysis and design for this high-visibility project and provided construction support.
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