Working as a sub-consultant to HunterH2O, Australia, Otak undertook water resources assessments for water supply in three towns in Papua New Guinea. The assessments included installation of hydro-logical monitoring systems and hydro-geological assessments (pumping tests and groundwater modelling) to confirm the most suitable water source, or combination of sources, to meet demand projections, with due consideration for climate change. Otak also prepared an outline environment management plan and social impact assessments for each water supply system, requiring household surveys and focus group discussions.
Expertise: Environmental
Rocky Mountain National Park Fall River Entrance Improvements and Environmental Assessment
The existing structures at the Fall River Entrance Station, built in the 1960s as part of the Mission 66 program, were aging to the point of contributing to employee health and safety concerns. Along with an entrance station needing to handle increasing visitation numbers, updates to the facilities would be designed.
Addressing Park Health, Safety, and Congestion with a New Facilities Design
Rocky Mountain National Park had concerns with the Park Fall River Entrance included poor air quality from exhaust fumes of queuing vehicles and inadequate space for completing shift reports, taking breaks, and coordinating work tasks. The entrance station also needed to be updated to address these problems and to handle increasing numbers of visitors as well as even more diverted traffic from Beaver Meadows to reduce traffic congestion and delays in Estes Park on US Highway 36. Through this task order, Otak is completing an integrated process following NPS protocols and requirements that includes predesign and schematic design of alternatives, completion of an environmental assessment and assessment of effect (EA/AEF) and preparation of a full schematic design report.
Rain Garden Handbook for Western Washington
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.
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.).
Zackuse Creek Restoration and Culvert Replacement
With the potential to support a large kokanee spawning run, 450 linear feet of Zackuse Creek was identified to be reestablished and restored. The effort includes replacing an existing downstream culvert on East Lake Sammamish Parkway with a fish passable box structure.
Supporting Fish Spawning and Passage with a Restored Stream
Despite favorable fish features, an evaluation of Zackuse Creek revealed that spawning kokanee had been frequently observed in low numbers below the East Lake Sammamish Parkway barrier culvert. Over several decades, the lower reach of the creek experienced sediment deposition in an alluvial fan wetland from natural and developed conditions. The creek channel has migrated to converge on East Lake Sammamish Parkway SE, causing embankment failure and the introduction of roadside pollutants. This work included altering channel morphology to enhance the way the stream transports its sediment load as well as restoring, improving, and sustaining aquatic habitat.
Warren G. Magnuson Park
The Seattle Department of Parks and Recreation envisioned transforming a former U.S. Navy airfield into a restored wetland and natural habitat that’s fully integrated with an urban park. A trail system within the wetland complex would also provide access to five newly constructed athletic fields.
One of Seattle’s Largest Wetland Mitigation Plans
In what was at the time the largest compensatory wetland mitigation plan in the City of Seattle, Warren Park also included continued extensive wetland monitoring. That monitoring would include collecting data on vegetation performance, water quality, amphibians and macroinvertebrates, among other parameters. The unique habitat design that combines wetland mitigation with a public park also retrofitted the existing stormwater system to improve water quality and provide hydrology to the wetland. Otak led the environmental design and extensive permitting across local, state and federal levels for the 65-acre habitat and park.
US 20 PME Hydraulic Engineering and Environmental Mitigation
The US 20 project is of statewide significance as it provides transportation system efficiencies and improved safety that increased economic activity between mid-Willamette Valley and the Oregon Central Coast. The project replaces a ten-mile segment filled with hairpin turns and narrow lanes with a new straighter 5.5 mile segment.
Steep Stream Channels Designed for Statewide Transportation System Efficiency
Otak was the project hydraulic engineer on the ODOT led project delivery team for Phase 3 & Phase 4, including the design of steep stream channels, slope pipes, outfall energy dissipators, water quality treatment facilities, stormwater flow control facilities, and revisions to the Stormwater Management Plan. Otak was the prime consultant hired to design and then administer construction for Environmental Mitigation (Phase 5) which involved floodplain reconnection, wetland creation, large wood installations, and revegetation at 7 different sites. Otak was the design engineer on a team that delivered Turnkey Environmental Mitigation (Phase 9), including the protection of forested headwater areas, removal of a fish blockage, restoration of a creek, floodplain reconnection and wetland creation.
Hood Canal Estuary Restoration at Cattail Lake
After more than 60 years artificially isolated from tidal influences, the opportunity to restore Cattail Lake was initiated as part of mitigation for construction at nearby Naval Base Kitsap. A new bridge, selective revegetation and complete permitting strategy are features of this mitigation plan to restore intertidal functions.
A Bridge Design and Mitigation Plan for Estuary Restoration
Restoration of the estuary off the Kitsap Peninsula in northwest Washington included the eight-acre, freshwater Cattail Lake that had been impounded on Hood Canal. The design reestablishes intertidal, riparian, and upland habitats with selective revegetation while a new bridge replaces two under-sized culverts to provide anadromous fish access to the watershed. Hydraulic analysis determined the new stream channel width as well as its scour potential. That analysis informed the single span bridge design, from its 100-foot length to the recommended riprap and deep foundations installed as scour countermeasures. Through research and design, Otak led this project while also playing a key role in coordinating with the Army Corps of Engineers, National Marine Fisheries and US Fish and Wildlife Services, Washington State Department of Ecology, and Washington Department of Fish and Wildlife for necessary permitting.
Bend Whitewater Park
A dam built on the Deschutes River at Colorado Avenue in 1911 was a significant safety hazard and required the 160,000+ annual river users to exit the river and portage around the impediment. In replacing the Colorado Avenue Dam, three channels were created in the river to provide locals and tourists with river recreation experience, right at the center of Bend, Oregon.
Balancing Recreation with River Health
Bend Whitewater Park features a number of elements intended to meet the overarching goal of balancing recreational access with health of the Deschutes River. The design removed life-threatening rock and steel pilings and enhanced protections for natural habitats while expanding recreation opportunities by creating two whitewater channels (one for expert and one for beginner river enthusiasts). In accounting for a 100-year flood event and revising flood insurance rate maps, a conditional letter of map revision (CLOMR) and letter of map revision (LOMR) were developed. The project also replaced the bike/pedestrian bridge that connects McKay Park to Miller’s Landing Park on either side of the river and provides a platform for public observation of the river recreation in the Whitewater Park.
Beaver Creek Bridge
The Beaver Creek Bridge, located on Hwy 47, is approximately 10 miles south of Vernonia, Oregon. Due to structural deficiency and stream constriction the single span bridge would be replaced.
A Seismic-Resilient Replacement for a Bridge with Structural Deficiency
Due to a deep soft layer of soil discovered during geotechnical explorations, the bridge is design to be supported on piling while the abutments are supported by tied back sheet piling. This is to preclude lateral spreading during a seismic event. Additionally, cellular concrete will be used for a portion of the roadway fill to minimize settlement. Rapid bridge construction techniques were incorporated into the project to limit the overall road closure time to two months.