WSDOT Projects

Map of the property being evaluated at the Port of Grays Harbor. See larger map. 


 

WSDOT employees and a tour group walking on the pontoons supporting the columns and roadway of the SR 520 Evergreen Floating Bridge across Lake Washington.


Waves batter the pontoons of the SR 520 bridge over Lake Washington during a winter storm.


A tour group looks at the hatches inside a pontoon.

Project Facts

• Pontoons are about as long as a football field, approximately 360 feet long.
• The anchors that hold the pontoons of the SR 520 bridge in place weigh 77 tons - about the same as 10 African elephants.
• The new pontoons will be about 20 feet tall, as tall as a two-story building.

Overview

WSDOT is advancing pontoon construction to restore the floating section of the SR 520 Evergreen Point Floating Bridge in the event of a catastrophic failure. If the SR 520 bridge failed, it could take several years to construct pontoons and restore the bridge for drivers.

Crews would construct and store pontoons until they were needed for a recovery effort. If the pontoons are not needed for emergency use, they would be used for the planned replacement of the SR 520 bridge.

We are exploring pontoon construction at an existing facility in Tacoma in addition to a proposed new facility. The existing facility, however, does not have the capacity to produce all the needed pontoons in a timely manner. We are currently evaluating a property at the Port of Grays Harbor as a potential location to build several pontoons at the same time. Various deep-water locations in Grays Harbor are also being evaluated to store completed pontoons until they are needed.

Why is WSDOT building pontoons?

Pontoons are the foundation of a floating bridge and can take several years to construct. They are large, hollow concrete structures designed to support the weight of the road, plus the cars, trucks and buses that use the bridge daily. The SR 520 Pontoon Construction Project is a critical step toward restoring the existing SR 520 bridge as soon as possible in the event of a catastrophic failure.

The timely availability of new pontoons is a critical element of restoring the bridge for drivers and maintaining a critical link - the SR 520 corridor - to the region's transportation system and economy.

The End Result

If the Evergreen Point Bridge were to fail, we would be prepared with pontoons to replace the floating section of the SR 520 bridge in a timely manner. If the SR 520 bridge does not experience catastrophic failure, the pontoons stored for catastrophic failure recovery would be used for the planned replacement of the SR 520 bridge.

Project Benefits

Safety

The pontoons for the SR 520 bridge will be designed and built to:

• Withstand a 1,000-year earthquake event.
• Withstand widnstorms up to 95 mph.

Reliability

Currently, 115,000 vehicles cross the bridge each day. There is not an available detour designed for or capable of accommodating additional traffic at equivalent speeds or travel times. Economic and social impacts on the region are likely to be substantial if the SR 520 bridge were to fail. Advancing pontoon construction would allow the region to avoid an additional three years of SR 520 bridge closure and the resulting adverse effects on the transportation system and economy.

What is the project timeline?

 2009
- Issue draft environmental impact statement (1st quarter).
- Issue final EIS (4th quarter).
- Prepare contract advertisement for pontoon construction at existing facility.

2010
- Issue contract advertisement for pontoon construction at new facility.
- Build new pontoon construction facility.
- Begin pontoon construction at existing facility.

2011
- Begin construction of pontoons at new facility.

Public Involvement

We are gathering comments from the public, community stakeholders, Tribal nations, and federal, state and local agencies on the project's draft purpose and need, range of alternatives, and environmental topics we will analyze in the project's environmental impact statement.

Please visit the project library for information presented at the Jan. 17, 2008, public scoping meeting in Hoquiam, and a summary of comments (pdf 68 kb) received during the comment period.

Environmental Protection

We are preparing an environmental impact statement (EIS) to evaluate potential effects to the surrounding environment from constructing and storing pontoons. Environmental specialists will conduct several investigations this summer to understand the context of the environment at the Port of Grays Harbor. This information will be used to evaluate if and how the proposed project may have an effect on water quality, native species and other environmental conditions. We plan to release the draft EIS for comment in the first quarter of 2009.
Please visit the WSDOT Environmental Services Web site for more information.

Increasing safety is one of our priorities

SR 520 is a critical link in the regional transportation system. A catastrophic failure of SR 520 could have severe effects on the regional transportation system and economy. Constructing and storing pontoons now would allow the region to avoid an additional three years of closure on SR 520 in the event of a catastrophic failure.

The pontoons for the SR 520 bridge will be designed and built to:

• Withstand a 1,000-year earthquake event.
• Withstand windstorms up to 95 mph.

Will this project impact tribal resources?

The project team is working closely with WSDOT's cultural resources staff to determine whether potential sites contain historic or cultural resources. The team and cultural resource experts have begun preliminary investigations at the Port of Grays Harbor site regarding historic or cultural resources, including:

• Coordination with tribes and federal and state resource agencies.
• Monitoring geotechnical borings.
• Researching local written archives.
• Conducting preliminary field investigations.
• Notifying nearby Tribes of WSDOT's interest in the site.

The team will continue to research the potential evidence of historical and cultural resources by conducting additional field studies and continuing to work with the community and the tribes.

Financial Information

The project is funded through the following sources:

• 2003 Gas Tax (Nickel Funding)
• 2005 Transportation Partnership Act (Transportation Tax Package)

This project has funding for environmental documentation, preliminary design engineering and selective right-of-way acquisitions. Depending on available funding, WSDOT plans to begin building pontoons at an existing facility in 2009, develop a new construction facility, and begin constructing pontoons at the new facility by 2011.

How can I get more information?
Contact:

For comments and questions about the project, or to be added to the mailing list or e-mail list, please e-mail pontoons@wsdot.wa.gov. 

To listen to a recording of the latest project information and leave a verbal comment or question, please call the project hotline at 1-888-520-6397.

To contact the project office by mail:

SR 520 Pontoon Construction Project
600 Stewart Street, Suite 520
Seattle, WA 98101 

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