By Geoff Crook
If you were in a car today speeding across Oregon’s temporary Interstate 5 bridge over the Willamette River between Eugene and Springfield, the only major scenic changes you would notice would be the cranes, forklifts, and soundwalls involved in the construction of a new bridge alongside. If you looked a little closer, though, you would find that the design and construction of this project is fitting in with and enhancing the environment around it.
As the largest bridge replacement project in the $1.3 billion Oregon Transportation Investment Act III State Bridge Delivery Program, the Willamette River Bridge is also one of the most visible from an environmental perspective. The Oregon Department of Transportation’s (ODOT) project team is carefully executing its plans to ensure that the structure’s ecological footprint is as small as possible, leaving room for natural habitats to flourish. Although all ODOT projects strive to avoid, minimize, or mitigate their impacts, the replacement of this bridge is taking ODOT’s environmental stewardship to a new level.
Surrounding the bridge on both sides are Alton Baker Park and the Whilamut Natural Area — land covered with grass prairies, flowering plants, and giant Douglas fir and oak trees. Western pond turtles and North American beavers call the riverbanks home. Oregon chub, chinook salmon and steelhead, and bull and rainbow trout spawn and feed in this area of the river. Myotis bats, herons, osprey, hummingbirds, and butterflies find shelter in the trees and on the bridge itself. When the project is finished, ODOT wants these habitats to be equal to or better than their current condition.
The bridge is surrounded by the trees and plants of Alton Baker Park.
ODOT’s challenge was to design and construct this major crossing within the physical constraints of the river and adjacent park lands, while also meeting community needs. To accomplish this, ODOT collaborated with area residents, community stakeholders, and public agencies, such as the city of Eugene Parks and Open Space, Lane County, Willamalane Parks and Recreation District, Oregon Parks and Recreation District, and the National Park Service.
ODOT also prepared an environmental assessment, in conformance with the National Environmental Protection Act requirements, to determine whether the project would have a significant effect on the human and natural environment. The Federal Highway Administration signed its Finding of No Significant Impact for the project in December 2008.
As part of the bridge program, ODOT developed a unique set of programmatic permits based on the use of environmental performance standards to guide design and construction activities. This permit strategy helped ODOT stay on track with permitting timelines for much of the bridge work while reaching better environmental outcomes on the ground. The bridge program’s environmental programmatic permits combine more than 14 separate environmental regulations into a single set of standards to meet its streamlining and stewardship goals.
To implement this strategy, ODOT formed the Programmatic Agreements Reporting and Implementation Team (PARIT). This multi-agency, collaborative workgroup comprises 11 state and federal regulatory agencies: the Oregon Departments of Fish and Wildlife, State Lands, and Environmental Quality; U.S. Army Corps of Engineers; National Marine Fisheries Service; U.S. Fish and Wildlife Service; Federal Highway Administration; Bureau of Land Management; National Oceanic and Atmospheric Administration Fisheries Service; U.S. Environmental Protection Agency; and U.S. Forest Service. All of these agencies have an interest in how the Willamette River Bridge project integrates with the natural and human environment.
Having the PARIT liaisons available to the Willamette River Bridge project team makes it easier for ODOT’s designers and contractors to comply with performance standards and resolve issues to their best possible outcome. PARIT involvement has been important for maintaining thresholds on issues such as in-water work extensions, hydro-acoustic monitoring, and timing and need for mitigation.
Use of the programmatic permits and the PARIT has been invaluable for streamlined delivery and permit reviews, has opened up communication between agencies, and as a result has saved a significant amount of time and money.
Dismantling and rebuilding
Tearing down the original 2,000-foot-long, 50-foot-high Willamette River Bridge had the potential to be highly disruptive to water quality, while generating a large amount of construction waste. ODOT’s project team spent months planning and preparing a demolition process that greatly minimizes impacts to surrounding parks or roads, ultimately deciding that excavators should pull the obsolete structure apart from a work bridge built below the existing structure.
The project team built a wood and steel work bridge — stretching across the width of the Willamette River and about 10 feet above the high-water mark — to support workers and the machines used for demolition and the construction of new bridge bents. One of ODOT’s primary goals was to prevent all construction debris from entering the water, so the work bridge doubled as a containment structure to protect the river below. The work bridge will eventually be taken apart and reused on the other side of the new bridge for additional construction, cutting down on waste and the cost of a second structure.
Wood, concrete, and steel from the demolition process — disassembled by hammers that ran on all-natural canola oil, which reduces risk of river contamination — yielded approximately 30 million pounds of debris, which was either shipped to local recyclers for processing or reused on this or other ODOT projects as fill. Some of the salvaged beams are even being used to build spans for a bicycle-pedestrian viaduct along the south bank of the Willamette River, adjacent to the project. The new multi-use path will improve connectivity between the cities of Eugene and Springfield, and will cross area creeks that will be fully restored by the end of the project.
The bridge crew uses a “bubbleator” to reduce sound pollution.
During construction, fish populations need to be protected from hydro-acoustic impacts that can negatively affect communication and migratory patterns. To attenuate the noise from underwater pile driving, the contractor places a noise attenuator (or “bubbleator”) around each pile template, designed for two piles. The “bubbleator” is a custom-made, circular device constructed of sheet metal and lined with high-density polystyrene foam. Aluminum pipes frame the piles to produce a thick wall of frothy bubbles, thus dampening sound from pile strikes. Because of its large size, the frame of these devices also serves as a safe, sturdy work platform for crews during pile driving. Hydro-acoustic monitoring on the project has shown attenuators are maintaining noise levels below required thresholds.
When the new I-5 Willamette River Bridge is complete in 2013, the final product will be a marked improvement from the original, with an overall reduced footprint and improved aquatic function. The bridge’s deck-arch columns — on separate northbound and southbound spans, side by side, 16 feet apart — will dramatically minimize the volume of structure in the river channel by touching down in the river only once in the middle on a natural island. In contrast, the original bridge had five piers in the river, and the temporary bridge has eight.
ODOT’s management of this project includes improvements not only to the bridge but also to the park lands. The agency will repave walking and biking paths for safer use and restore twice the number of native trees and plants to the area. Monitoring and maintenance of these areas will continue for at least five years after completion.
A blue heron rests on a log near the I-5 Willamette River Bridge.
Another notable improvement will be the restoration of tributaries connecting Augusta Creek and Glenwood Slough. Over time, these upper habitats have been cut off and degraded by urban development, thus depriving fish of access. Now, the project team is removing a concrete-lined channel, restoring streambanks with extensive native plantings, and removing barriers to fish migration.
ODOT’s mission is to provide a safe and efficient transportation system that supports economic opportunities and livable communities, and the I-5 Willamette River Bridge replacement is meeting that mission. The project is about moving people, goods, and services safely through the Willamette Valley, but it is also a conscious effort to ensure long-term and meaningful enhancements for the human and natural communities that call this area home.
Geoff Crook is the environmental program manager at the Oregon Department of Transportation.