The flood reduction at South 180th aimed to address longstanding flooding issues in the area caused by a ditch with inadequate capacity. A critical areas assessment developed solutions focused on the goal of reducing flooding through flow control and additional conveyance capacity.
A Critical Area Assessment to Solve Persistent Flooding
Flooding at 180th would happen several times a year. An evaluation of flood risk to adjacent properties as well as capacity for the ditch and downstream drainage system delivered alternatives using both conventional or natural drainage systems. These alternatives considered factors such as construction cost, right-of-way availability, property acquisition, erosion in downstream ditches, and permitting requirements. Otak played a critical role in this project, providing project management, topographic survey, hydraulic and hydrologic modeling, and stakeholder engagement. The evaluation has the South 180th Flood Reduction project well-positioned to succeed in its mission to reduce flooding and protect the surrounding properties and community.
An evaluation of options to manage hydrology in the Smith and Bybee Lakes complex led to the restoration of its connecting channel and subsequent mitigation of seepage found in an existing levee. The design adds capacity to the connection channel through excavation, allowing Metro to better manage water levels in the lakes. Otak led the hydraulic modeling of the system to compare the benefits derived from varying levels of channel excavation for the resulting restoration design as well as alternatives analysis of proposed remedies for the levee hazard mitigation design.
Levee Seepage Mitigation and a Restored Channel for Improved Hydrology Management
From the simulation of spring freshet floodplain functions to control of invasive species and habitat for migratory waterfowl, Metro manages water levels across the seasons in Smith and Bybee Lakes for a variety of objectives. A control structure was constructed in 2003 to aid in this management. However, the water levels in Smith Lake were not responding to control structure manipulations due to sedimentation and partial obstruction in the channel connecting Smith Lake to Bybee Lake. After comparing options, a design concept to excavate the channel and restore capacity was developed along with the construction documents. After construction, an inspection revealed seepage in the levee near the control structure and also identified burrowing animals which further increased a risk of levee failure. An alternatives analysis to resolve the issue led to a 200-foot-long sheet pile cutoff wall with segments on either side of the water control structure. With the piles driven 20-feet below ground surface, the design increases the sub-surface flow path to reduce seepage to minimal levels while providing a physical barrier that prevents animals from burrowing.
In November 1805, the Lewis and Clark Expedition reached a site along the lower Columbia River they named Station Camp. Located in current-day Washington state, the riverfront site was redesigned to become a National Park Unit of the broader Lewis and Clark National Historical Park.
A Historic Site with Tribal Heritage Designed to Benefit the Public
While the site carries significance to the Lewis and Clark Expedition, that event represents only a small part of its history as a long-time summer village of the Chinook Nation. Once an important trading site for tribes on the Columbia over the course of centuries, Middle Village / Station Camp Park is now designed to serve as an outdoor commemorative park and interpretive landscape with elements that tell the important story of the location. After an unintended archeological discovery at the site, revised plans moved forward in meeting the broader vision of promoting the region’s rich history. The updated park master plan and final design plans for the site also address parking and pedestrian circulation, as well as low impact measures for stormwater facilities, earthwork, and wetland mitigation. Visitor orientation, accessibility, safety, and site connectivity were all included as important design considerations. In leading the design, Otak also developed the NEPA Environmental Assessment and worked closely with representatives from the Chinook Indian Nation and other tribes throughout the course of the project.
The Ash Creek Bridge on F Street in Independence, Oregon had become structurally and functionally inadequate. A modern structure that supports the transportation infrastructure of the community and enhances the surrounding public spaces – including a unique historic bridge railing system – was designed by Otak as its replacement.
Modern Bridge Replacement, Improved Transportation Infrastructure
As a timber-supported concrete structure on a local collector, the Ash Creek Bridge was only sufficient to pass light, local traffic. The replacement turns that existing three-span concrete bridge into a single-span prestressed concrete bridge, enhancing the route for local traffic as well as community use. The design introduced new raised sidewalks for bicycle and pedestrian traffic while also including a new urban bridge rail that increases protection for pedestrians without causing a blunt end issue for vehicles. With the addition of low-level pedestrian lighting and ornamental handrails, the bridge was configured to enhance the adjacent Inspiration Garden public park. Stormwater treatment allows for sustainable runoff into Ash Creek and sheet pile scour protection prevents water from undermining the bridge foundation while remaining fish friendly. The team lead regular monthly discussions with the client throughout the process, reporting on progress issues and decision points. This collaborative process involved various stakeholders throughout delivery, which included survey, geotechnical, roadway design, bridge design, environmental permitting, and hydraulics analysis.
With the City of Burien receiving a grant through the Washington Department of Ecology, a multidisciplinary Otak approach led design and construction engineering support for the stormwater retrofit of Moshier Park. Plans for the project include a comprehensive design for park improvements to benefit local waterways as well as the community at large.
Low Impact Development Stormwater Management Meets A Community Center
Restoration and preservation are an increasing priority in King County, Washington which is home to various native fish species including Coho Salmon. The Moshier Park public works project balanced a number of priorities with the ultimate goal of improving water quality to the Miller Creek watershed. Designed to mimic functions of the region’s naturally forested area, a number of green stormwater management techniques would return aquatic habitats to healthy levels while also addressing localized flooding that’s caused erosion along Miller Creek. Those improvements include two infiltration galleries, permeable pavement in the parking lot and sidewalks, onsite bioretention facilities, and biofilter treatment structures. Design of these features are seamlessly integrated with broader objectives for 15.2-acre public park’s place in the community. Adjacent to a high school and Burien’s Art Center, Otak coordinated with multiple stakeholders to build consensus around planned reconstruction of the concessions/restroom building and retrofit of the primary athletic field and parking lot to optimize the multi-purpose park’s usage as a true community center.
For coastal communities, resilience design has shifted from nice-to-have to necessary
With a rapidly warming planet and increasing ferocity of weather patterns, coastal adaptation through resilience design has an added emphasis for today’s built environments.
It’s for good reason too. Currently, more than 50% of the US population – some 164 million Americans – live in coastal watershed communities while generating 58% of the nation’s gross domestic product (GDP). And that number is only growing as more than 1.2 million move to the coast each year.
These coastal communities often bear the brunt of unpredictable weather and seismic events. Vulnerable communities like these must be resilient by design, and able to bounce back after even the most intense storm, tidal wave, earthquake or other catastrophic event.
Sustainability in planning and design, a core tenant of Otak’s mission, aligns directly with an approach to coastal adaptation. In this piece, we’ll discuss how a focus on coastal adaptation planning and resilience design translates into stronger coastal infrastructure and communities, at a time when they’re needed more than ever.
Coastal Resilience is defined as “building the ability of a community to bounce back after hazardous events such as hurricanes, coastal storms, and flooding—rather than simply reacting to impacts.”
Resilient design is a matter of preparedness, of being ready for natural hazards before they happen, and of informing clients to be aware of all factors in the design-build process. For example, the overdue cascadia earthquake presents a significant challenge in designing along the coastal fault line. Decisions and plans need to be made to anticipate and mitigate these environmental inevitabilities.
An illustration of how resilience design allows for quick recovery and multi-purpose utility of building operations during a catastrophic event
Why is Coastal Adaptation and Resilience Design Important?
Such high priority is placed on the resilient design of coastal communities for a variety of reasons. Among them is the simple fact that it’s a matter of survival. Not just the survival of the people in that community, but also the survival of critical infrastructures like power grids, water management systems, bridges, and schools.
This causes us to ask unique questions when we go to work. For instance, how will this community function when, not if, a major environmental event happens? How can existing structures be made into multi-use facilities in times of crisis? Most of all, how can the community adapt to these impacts? It all comes back to how these questions are answered during resilience design and planning.
4 Elements of Coastal Adaptation and Resilience
While there are a variety of variables that come with each specific situation and environment, there are also some overarching factors that impact any coastal resilience planning. These factors help assess vulnerabilities, investigate possible solutions, and set priorities among options that address those highest risks.
As a foundation for designers and planners, these factors can help communities, cities, regions, and governments quantify their vulnerability and risk, while prioritizing people, ecosystems, and economics into their plans.
1. Structurally Sound Built Environments
The first step to designing these communities is making sure all buildings are structurally and architecturally sound.
Regional specifics inform these design choices for coastal structures, like adding stilts to houses to account for sea-level rise, among others. It’s about taking a long-term view of creating a space, being mindful of how the community lifecycle will function in 50-100 years into the future.
2. Design for Environmental Sensitivities
Local environments have a direct impact on the vulnerabilities and potential hazards that need to be considered during coastal resilience planning. Those details, such as water restoration, also factor into the design of structures themselves and how recovery will affect the surrounding area.
Especially when talking about environmentally sensitive sites, the design should match those nuances and be able to respond to the natural environment accordingly. This can inform decisions down to the last detail. For example, the choice between building with stainless versus galvanized steel can be critical in ensuring the resilience of the structure.
3. Efficiency and Sustainability in Upkeep and Recovery
As hazards and extreme events become more commonplace, the question now often becomes not how does coastal adaptation planning avoid damage, but rather, how does it allow structures (and communities) to recover after the fact?
What happens in the aftermath of a catastrophic event can be equally, if not more important than what happens during. The ability for infrastructure to remain functional, despite sustaining damage, can be all the difference when the fundamentals for survival are at a premium.
How a built environment operates outside of a catastrophic event also has an impact. Limiting the amount of maintenance and upkeep increases preparedness while efficiency and sustainability factors help ensure that built environment isn’t contributing to the underlying causes of climate change while also keeping the costs of waste at a minimum.
4. Planning for Community Vulnerabilities
The process of coastal adaptation and resilience is a constant state of analysis, an ongoing attempt to answer the question of how these communities will function both before and after a catastrophic event.
Building resilience and equity into planning is ultimately about protecting people and saving lives. And it’s important to recognize that certain areas or demographics of a single community can often be more vulnerable than others. Addressing these disparities should come through in the design of infrastructure and the intent behind its built environments.
Adaptive-use structures, or buildings with more than one purpose, are just one way to account for this issue. This means designing spaces like schools that can become shelters with their own generators in case of power grid failure, or we add height to bridges to account for flooding. When we design with intention of keeping people safe, communities are better able to respond on their own until help arrives and are ultimately more prepared to survive.
Pre-Existing Structure2D Modeling for 100-Year-PlanningConstruction of Three-Span BridgeOnce considered the second most hazardous bridge in Oregon, Lommen Bridge was at risk of collapse. Using the latest resilience technology, Otak replaced the structure while designing for sustainable elements like rain gardens, erosion control, and drainage features.
How to Approach Coastal Adaptation with Resilience Design
While there are a multitude of factors that must be accounted for when planning a community’s resilience design, the approach is often threefold:
Assess regional risk in resilience design by understanding the locations, unique environmental factors, cost details, and most importantly opportunities for improvement in any building phase.
Plan how structures will function during hazardous events, and be converted for multiple uses in times of crisis.
Considerthe sustainability of the structure and how it will be used 50-100 years from now, understanding the current carbon footprint and how to reduce it.
However, there are societal and social factors that go into how resilient communities are designed which should also be taken into account.
Identifying Social Vulnerabilities
It is critical to note here that climate change and weather events affect lower-income and houseless people to a higher degree than those with more resources. Clients need to be advised of the social impacts their projects entail because there is a relationship between houseless populations and how we plan for resiliency.
The lack of reasonable, low-income housing is just one issue that exacerbates this reality, which is why resilient communities must account for the whole of the population. Encouraging clients to think about these ideas ultimately makes for a stronger structure that can serve everyone, regardless of socioeconomic background. The reality is natural hazards do not discern between social standing, and communities that are truly resilient are also built with equity and the marginalized in mind.
Accounting for Climate Change Adaptation
While designing with resilience in mind, it’s imperative for coastal communities that projects come down to client goals. It’s important to gauge how clients feel they play into a municipality’s ability to adapt, using this information to inform how we present solutions to their problems.
During resilience planning and design, it’s of utmost importance to stress what the intent of the development truly aims to accomplish. Again, all pieces of infrastructure must be structurally and architecturally sound while meeting those goals.
The result is a resilient community with that also benefits from a reduced carbon footprint in the process.
Climate Change is Impacting the Risks Faced by Coastal Communities Including Increased Flooding
Lake Shorelines versus Ocean Shorelines
It’s also important to note, not all coastlines are the same. Resilience on shorelines doesn’t just apply to coastal communities. In fact, inland lake shorelines (not to mention river, creek and other shorelines with their own unique properties) must also be planned with a resilient design top of mind. The differences are plenty, however, there is a key distinction between the two.
For instance, if a coastline is not fraught with natural disasters every day, clients can take advantage of good weather conditions by harnessing alternative energy sources like solar power, wind power, and hydraulic power.
Inland lakes lack a tidal risk factor, meaning that communities along ocean shorelines must contend with events like king tides, or tidal shifts that can drastically affect the ferocity of coastal storms. While wind hazards are risk factors for both types of shorelines, there are decisions that need to be made when dealing with one versus the other.
Coastal Resilience Examples: How Otak Builds Resilience in Coastal Communities
Much like the weather events we’ve discussed, Otak’s work is also defined by intersections, and one of the biggest of these is the relationship between our built and natural environment. So, what makes our approach unique?
For one, Otak’s experience is multinational, meaning we have experience across different types of coastlines worldwide and have utilized design solutions that other firms may not have access to.
As a globally positioned organization, Otak has a unique vantage point that cannot be replicated. Just one example of our experience with different locales is our work for the Nestucca Valley School District, a rural educational model that satisfies our requirements of resiliency in an area at risk of wildfires. The school was renovated for existing students but designed for the whole community as a multi-use facility. With a full generator system, and grass fields big enough for helicopter transport, the school can house 3000 people with full power for 3-4 days.
Nestucca Valley Emergency Use Project
Second, Otak’s experience with public infrastructure sets us apart. Not only are we designing for structures that can stand up to harsh weather events, but we’re also planning for how quickly these buildings can bounce back, post-event. This can affect systems like a community’s water supply, wastewater management, and transportation infrastructure.
That’s why we build redundancies into existing systems. From making sure bridges are high enough to account for sea-level rise, to making sure secondary routes are available for evacuated motorists, to installing multiple pipelines in case of earthquakes. When it comes to resilience design, Otak’s work with coastal communities means we can walk our talk.
Want to discover more sustainable projects? Check out more examples of our work in sustainable, resilient design spaces and see how they aim to serve every aspect of the community.
All three bridges on Salmon Creek south of Battle Ground in Clark County were categorized as scour critical. Installation of subgrade riprap as a scour countermeasure would be required as part of repairs and a self-mitigating design.
Scour Repairs Meet Mitigation Planning
In addition to scour repairs and the associated permitting, the Salmon Creek Bridges required substructure repair. Improvements to Lehto Bridge would also include new soil nail wingwalls. The permitting approach involved design of subgrade riprap to not adversely affect fish habitat and the inclusion of channel grading that maintains no-rise of the regulated floodplain. Additionally, creative identification of existing issues, including derelict riprap at the streambed surface, allowed the project to be considered self-mitigating and not require off-site mitigation. The Otak team led the design and permitting in repairing these structures while protecting local habitats.
It isn’t often that our engineering profession delivers infrastructure projects that actually enhance and create salmon habitat by allowing the restoration of natural processes. This was the case for the 750-foot long river-worthy and salmon-friendly Dungeness River Pedestrian Bridge constructed in 2015 for the Jamestown S’Klallam Tribe. Now, six years later, the bridge and habitat restoration have proven to be a real benefit to the river, salmon habitat, and the 1000+ pedestrians and bikers who cross the bridge daily. The increased bridge traffic has also brought new opportunities to the Jamestown S’Klallam Tribe and plans for a bridge extension and new nature center are underway.
The bridge design allows the Dungeness River to naturally migrate, increasing the potential for fish-bearing habitat.
2015 Flooding Destroys Existing Trestle
In February 2015, during a large flood event, the Dungeness River avulsed laterally approximately 100 feet and destroyed two bents of the existing bridge trestle. The trestle carried the popular Olympic Discovery Trail near Sequim, WA and the closing of the damaged bridge sent ripples through the community. The owner, the Jamestown S’Klallam Tribe, immediately began applying for grant funding to restore the crossing, and after months of effort, secured several grants that were primarily focused on salmon recovery.
Otak was selected and began design work in May 2015. Preliminary meetings with the Tribe and the stakeholder group allowed an expedited alternatives evaluation and selection process, and the final design was completed by the end of July 2015.
New Design Reinforces Stability
The new bridge design included four main spans of 185-feet each, which were prefabricated steel trusses with a concrete deck and a 30-foot wide section in the center to create an overlook area. The bridge piers had a buried pile cap with driven piles down to bedrock and a single concrete column supporting a hammerhead cross beam.
A robust pier design ensures stability after deep scouring below the pile caps, including lateral water pressures on debris buildup. To make the bridge river worthy, the piers had to withstand river avulsions anywhere along the span. Because of the stoutness of the pier’s limited ductility for seismic performance, the superstructure was supported on seismic isolation bearings on top of the pier caps. Restrainers were incorporated into the design to limit maximum seismic displacements.
Dungeness River Pedestrian Bridge extension preliminary design.
Expedited Procurement, Permitting
To expedite procurement, the bridge sections were pre-ordered in July, with the main construction bid in August 2015. The site contractor was then selected and mobilized in September 2015. Environmental permitting was expedited including the US Army Corps of Engineers permit, which was applied for in June and granted three days before mobilization.
Spawning Salmon and Habitat Reformation
During the pre-construction walk-through, a pool in the Dungeness River was almost completely black—filled with more than a thousand spawning salmon. Because of the sensitivity of the river, caution was taken to minimize disturbance near and over the water. After the foundations and piers were complete and the bridge spans erected, a notice came in late November that heavy rains were predicted. The contractor immediately removed the temporary bridge over the river, and three days later a flood hit, which not only washed out the section of the river where the temporary bridge was but shifted the thalweg another 80 feet to the west—completely exposing one of the buried piers. Not to worry though, the bridge foundations were deep and structurally robust enough to withstand the river shifting and meandering. And, by doing so, new habitats are constantly being formed.
The complete removal of the existing trestle and replacement with longer spanning structures allows the Dungeness River to naturally migrate and thereby significantly increases the potential for fish-bearing habitat. As such, the bridge has been deemed salmon-friendly. The trestle replacement not only required a high level of engineering skill, but also engineering that had an appreciation for the natural sciences, with equal focus being on salmon recovery as well as the restoration of the popular trail linkage.
The grand opening of the bridge occurred on December 30, 2015, only eight months from the start of the design. Randy Johnson, Habitat Program Manager, Jamestown S’Klallam Tribe expressed the tribe’s appreciation for the new bridge the following November, stating “In contrast to the old bridge, the new Otak-designed bridge is environmentally friendly and river worthy. It has already been tested by several floods and has performed with flying colors. Trail users are enthralled with the bridge.”
Conceptual drawings: Dungeness River Pedestrian Bridge, nature center, and amphitheater.
Fast forward six years to the present and the tribe, working together with Otak, is beginning work on an extension for the bridge, as well as the partial removal of an existing levee to make the flood plan even wider. The bridge extension structure will essentially replace the portion of the levee being removed. In total, this will allow the river to run more freely and will further enhance ongoing river restoration. Designs are being finalized for the new bridge extension, which is on track to be completed in the summer of 2022.
Reconstruction of the nature center on the east side of the river began earlier this year. The new extension will provide improved access for visitors to the new Dungeness River Nature Center from the bridge, as well as access to a trail to a natural amphitheater and a bi-pass for pedestrians and commuters from Port Angeles who traverse the bridge and Olympic Trail daily.
King County, in Washington, is situated within a natural watershed, home to various native fish species, including Coho Salmon. Restoration and preservation have become a priority focus across the region with salmon runs declining due to loss of habitat, barriers to fish passage, and poor water quality. For cities like Burien, with sensitive Coho salmon-bearing creeks running directly through them, there is an urgency to address water quality and pollution from stormwater run-off.
Public works projects need to balance multiple priorities against available funding and budget restrictions. So, when Otak was hired by the City of Burien (City) to do the final design of a stormwater retrofit at Moshier Park along Miller Creek, the team took a multi-disciplinary approach. The goal was to resolve a complex set of issues and provide maximum benefit in conjunction with other planned park improvements.
Addressing Untreated Stormwater Runoff, Flooding
Miller Creek, a natural waterway for spawning Coho Salmon, crosses through urbanized areas and ultimately discharges into the Puget Sound. Due to the amount of untreated stormwater runoff draining from the creek basin, the health of the creek is greatly degraded and conditions are poor for supporting the aquatic habitat. In addition, localized flooding and erosion along the creek’s banks have resulted from existing vegetation being converted to impervious or less pervious surfaces.
Moshier Park is a 15.2-acre public park that features lighted athletic fields, a community arts center building, and a large parking lot that is also used by Highline High School for events at Highline Stadium. The park was identified as an area for a stormwater retrofit project, funded in part by the Washington Department of Ecology, which would have the highest benefit value to Miller Creek.
Balancing Priorities, Maximizing Opportunities
While the project’s primary objective was to retrofit Moshier Park to provide stormwater flow control and runoff treatment, Otak saw the greater opportunity to incorporate other park improvements the City wanted to complete. Otak project engineer, Tyson Hounsel, explains that “by packaging some of the other park improvements into the design and construction timeline, we were able to save the city both time and costs. Plus, through all of our teams—survey, architecture, landscape architecture, water and natural resources, and engineering—we could develop a comprehensive design that includes the stormwater facilities, as well as a synthetic sports field, and a new restroom and concessions building at the park.” Otak also aided in obtaining the necessary environmental permitting and will act as the construction manager to oversee the retrofit and park improvements through completion.
One of these key improvements will be converting the large asphalt parking lot to less-impervious surfaces and installing an underground water detention tank and treatment facility that will capture stormwater runoff. Interpretive signs will also be installed in the park, which will be used by the neighboring high school as well. The project will break ground later this summer and is slated for completion in 2022
In the end, the City will have a newly designed and updated multi-purpose park that, as Tyson states, “will be a real community center.” Miller Creek will also benefit from improved water quality and will provide a more hospitable environment for spawning Coho Salmon.
Otak is proud to announce that Ryan Makie, Water Resources Group Manager, has received the Patriot Award from the Employer Support of the Guard and Reserve (ESGR) program. Ryan was nominated by Army reservist and Otak Stormwater Planner, Cody Kent.
The Patriot Award is given to a soldier’s supervisor who offers support to the Army Reserve’s missions through measures such as flexible schedules, time off prior to and after deployment, caring for families, and granting leaves of absence.
“The whole office has been really supportive, and I wanted to recognize Ryan personally as a representative of Otak’s culture. Before deployment, I felt Ryan supported my service in the Army Reserves. During deployment, he went above and beyond and really shined. My wife and I had our first child in 2019 and, of course, 2020 was an incredibly stressful year for everyone with the pandemic and wildfires. Ryan kept me connected to Otak and reached out to both me and my wife to offer his support throughout the year. When I came back, despite all the changes, he helped me jump right back into work, and I quickly felt like I hadn’t left,” said Cody. Army Reserve soldiers commit to training one weekend each month and for two weeks every summer. They can also be called into full-time service to support Army combat missions, as was the case for Cody, who was deployed to Jordan for nearly all of 2020. He nominated Ryan when he returned to Otak in January 2021.
Ryan received the award during an online ceremony held June 9, 2021.
Ryan’s award reflects Otak’s commitment to stand behind our soldiers and the work they do to protect our country. We are happy to work with our employees who are in the Army Guard or Reserves and support the important commitments they hold outside of their employment with us.
“We are grateful for Cody’s service to our country and proud of the work he has done while deployed. The important skills Cody has gained during his service reinforce his professional growth here at Otak. We are honored to be able to support Cody and his family while he is hard at work with the U.S. Army Reserves,” Ryan commented.
Congratulations, Ryan, and thank you for your service, Major Cody!
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