A guide for design, installation, and maintenance, this handbook will guide you through the following stages: plan, build, plant, and maintain. The handbook is written for conditions specific to western Washington, including appropriate plant selections and sizing recommendations based on regional soils and rainfall patterns.
Expertise: Water Resources Engineering
Willapa Hills Trail Bridges
Three long-span bridges were needed for Willapa Hills Trail. The first two were replacements for the Dryad and Spooner bridges over the Chehalis River after the existing structures were washed out during an extreme weather event. The third structure, Littell Bridge, eliminates a dangerous at-grade crossing over a very busy State Highway. Together, with an Otak-led environmental assessment and structural design, all three structures provide safer, accessible, and more complete crossings as part of the local trail system in this Washington State Park.
Designing Multiple Structures to Create Safe and Resilient Trail Crossings
During the weather event that compromised the two existing structures, floodwaters swept the truss spans downstream and removed most, if not all, of the approach span structure. The resulting bridge debris removal occurred two years later. The Dryad and Spooner bridge structures are single span 300-foot-long post-tensioned steel trusses with precast concrete deck panels. Adding the Littell bridge near the Adna trailhead provides users a safe overhead crossing over SR 6. Previously trail-goers had to cross the road to continue their journey along the 56-mile Willapa Hills Trail that connects Chehalis in Lewis County with South Bend in Pacific County. In designing the structures for each crossing, this multidisciplinary effort also provided information on baseline river, geomorphic, and riparian habitat conditions and facilitated the permitting processes necessary for the project. This included SEPA documentation and compliance, impacts analysis, and aquatic permitting applications and support documentation (HPA, Lewis County critical areas compliance, etc.).
185th and 145th Street Light Rail Station Subarea Plans
To provide greater access to the region’s transit system and create vibrant transit-oriented neighborhoods, subarea plans were designed that propose future development around two new light rail stations in Shoreline, Washington. The subarea planning processes for both station areas engaged stakeholders and the community in shaping the future plans for the neighborhoods.
Transit Oriented Development Plans that Maximize Land Use and Community Mobility
The plans focused on maximizing short and long-term land use opportunities presented by the light rail stations, including a mix of residential, employment, and commercial uses. An emphasis on pedestrian and bicycle access between uses enhances development in the area while establishing a comfortable, attractive, and vibrant public realm. Creating effective transitions between the newly planning transit-oriented community and adjacent uses also maximizes opportunities for housing across a range of income levels and enhances the ridership base for the expanded transit system. In close coordination with Sound Transit, Otak completed the station subarea plans while also conducting analysis around an environmental impact statement, property values, fiscal conditions, and alternatives for an urban design that best suits the neighborhood in preparation of the station area plan.
Mae La Refugee Camp Water Resources
Otak worked closely with Solidarites International staff and the Mae La refugee camp ‘water committee’ to evaluate all existing water sources, storage and supply assets and develop a maintenance plan to improve water supply operations to all camp residents. Evaluated alternatives for a new water source to augment the supply during the dry season to increase drought resilience of the water supply system. These alternatives included additional springs, deep bores, a shallow alluvial aquifer, and an adjacent river. A dry season river flow assessment was undertaken and was deemed the most appropriate new water source. A new river intake 5km upstream of the camp and associated gravity-fed infrastructure was specified, including detailed costing and BOQ.
Abaiang Drought Management Plan
Otak developed a community drought management and response plan for the Island of Abaiang. This required detailed consultation with local government and community stakeholders to develop a pragmatic plan to prepare for, respond to, and manage the impacts of drought at village and island level. National level consultations were held with Ministry of Public Works and Utilities, Ministry of Internal Affairs, as well as the Disaster Risk Management Unit (advisers to Cabinet) to align with national policies and ensure an effectively streamlined communication plan – including when and how national emergency assistance will be coordinated. With Kiribati Met Service, we developed a simple method for triggering three warning levels of drought risk, including drought declaration. We provided capacity-building training to appropriate parties at a national and island level.
Whipple Creek Watershed-Scale Stormwater Plan
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
The final plan, approved by Ecology, presents a clear analytical approach, findings, and conceptual implementation plan, including cost estimates for stormwater retrofits.
Check out the completed Whipple-Creek watershed-scale stormwater plan on the County’s site. Otak helped Clark County complete its watershed-scale stormwater plan and comply with its NPDES Phase I municipal stormwater permit.
Columbia Palisades Subdivision
On a prime piece of 90-acre property overlooking the Columbia River, The Washington State Department of Transportation planned for an exclusive lifestyle community. The resulting Columbia Palisades Subdivision contains luxury residences, offices, parks and open space, a hotel, commercial buildings, and an open-air amphitheater.
A Public-Private Master Plan for Underused Lands While Maintaining Natural Resource Mitigation
Located on a historic rock quarry, the site has a 180-foot elevation change. At least 180,000 cubic yards of rocks and boulders were excavated to clear the way for 8,500 linear feet of roads, including a roundabout for efficient traffic flow. The complex stormwater design includes right-of-way catch basins, conveyance piping, and mechanical stormwater treatment and regional detention/discharge facilities. Close coordination with the City of Vancouver to create a subarea plan led to the Columbia Palisades Master Plan. Working with The Washington State Department of Natural Resources, planning included preparation of a quarry reclamation plan and natural resources mitigation plan. A successful public-private partnership, this important project is a prime example of redeveloping underused lands. Otak led various facets of master planning as well as land use permitting and infrastructure design in making this community a reality.
Lommen Bridge Replacement
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.
Shoreline Interurban Trail
The Interurban Trail follows its namesake trolley route from downtown Seattle to northern residential and rural communities in Shoreline and Snohomish County. Instead of rail cars packed with 20th century commuters, the trail is travelled by bicyclists, pedestrians, and equestrians seeking to enjoy the Puget Sound region’s natural beauty and evolving landscape.
A Trail Designed for Community Connectivity
Connectivity and community define the trail and its creation. In design development for the 24-mile corridor the Shoreline community was engaged in an extensive outreach program, while coordinating and meeting the needs of each of the route’s affected agencies and jurisdictions. Features include view lookouts, informational kiosks, gateway elements, and trolley-related wayfinding and mile-marker signage. Otak developed the preliminary design as well as construction and management for the trail’s three-mile north, south, and south-central sections in Shoreline.
Pringle Creek Stream Restoration
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.