WSDOT: Port of Tacoma possible site for SR520 pontoon construction

Washington State Department of Transportation (WSDOT) crews have started preliminary fieldwork to determine whether the Port of Tacoma would be a feasible site to build pontoons and anchors for a new State Route 520 floating bridge that will open to drivers in 2014.

WSDOT needs 77 total pontoons in various sizes for the new six-lane floating bridge. Crews are scheduled to begin construction on the initial 33 pontoons at a casting basin in Grays Harbor in spring 2011. This fieldwork study will help to determine if the Port of Tacoma site could be used to build some of the remaining 44 pontoons. WSDOT has also identified the Concrete Technology Corporation site in Tacoma, in addition to the Grays Harbor site, as potential pontoon construction locations.

Fieldwork at the Port of Tacoma is planned Monday through Friday for up to 20 working days. Crews will drill four borings measuring up to 150 feet deep, including two groundwater observation wells, and conduct other soil tests.

“The Port of Tacoma could provide contractors with an optional location for building floating bridge pontoons,” said SR 520 Program Director Julie Meredith. “We have an aggressive schedule to open a new floating bridge to drivers in 2014. We want to provide maximum flexibility to the contractor who will be responsible for constructing the new floating bridge.”

Earlier this year, WSDOT awarded a $367 million contract to Kiewit-General Joint Venture to build a casting facility and 33 pontoons in Grays Harbor. These 33 pontoons will either be used for emergency replacement of the current four-lane floating bridge or will be stored until needed for a new six-lane bridge. The Grays Harbor facility will not have enough capacity to build all of the pontoons needed for the entire six-lane floating bridge.

In August, WSDOT launched its search for qualified design-build teams to build the new six-lane floating bridge, including production of the remaining 44 pontoons. The floating bridge project is estimated to be valued at $700 million to $900 million and proposals are due next year. As part of the proposal process, WSDOT will make feasible pontoon construction sites available to the contractor teams, including the Grays Harbor and Concrete Technology Corporation sites, as well as other possible sites identified through fieldwork studies.

The state Legislature set the SR 520 program budget at $4.65 billion for improvements from I-5 in Seattle to SR 202 in Redmond. Toll revenue and state and federal funds provide about $2.37 billion for the SR 520 improvements. WSDOT will continue working with the state Legislature to identify additional funding to complete improvements in the corridor.

More information about the SR 520 Program is available at .