Fourth cycle of State Route 520 pontoons leaving Aberdeen casting basin April 15

The fourth cycle of pontoons headed for the State Route 520 bridge will be floating out of the Aberdeen casting basin late tonight. Deputy Executive Director at the Port of Grays Harbor Leonard Barnes told commissioners last week, the giant concrete structures will be floated to other terminals for inspection and preparation. Some are stored at a moorage facility in the harbor, North of John’s River until they are towed 260 nautical miles around the Olympic Peninsula to Lake Washington for the new State Route 520 floating bridge. Ian Sterling with WSDOT tells KBKW they have another six pontoons for the new SR 520 floating bridge ready to float out from the casting facility in Aberdeen. Crews plan to work through the night on Tuesday, April 15, with the first pontoon scheduled to leave the casting basin close to midnight to coincide with the high tide necessary for float-out. These six pontoons represent the fourth cycle built in Aberdeen, meaning two-thirds of the 33 pontoons being constructed there are now complete. Other bridge pontoons are being built in Tacoma. All told, 52 of the 77 total pontoons needed for the new bridge are now complete.
Six more SR 520 pontoons wait for high tide in Tacoma
Six more SR 520 supplemental stability pontoons are towed out of their Tacoma casting basin in pairs each evening, as the high tides allow.

Repair Work to Delay Float-Out of Pontoons

Seattle, WA- With the heavily planned and much anticipated 520 floating bridge pontoon construction project underway the Washington State Department of Transportation are now facing a delay of the float-out of SR 520 bridge pontoons built in Aberdeen after damaged concrete was discovered.

Work is planned on four of the six concrete pontoons under construction in Aberdeen and is preliminarily expected to take four to six weeks to complete. As a result, the completed pontoons are not expected to be towed out of the casting basin until July or August, depending on favorable tides. 

The Washington State Department of Transportation is working with contractor Kiewit-General to analyze the cause of the damage "We have a plan, and by making these repairs and modifications before the pontoons leave Aberdeen, we can assure that the new SR 520 floating bridge will safely carry traffic for 75 years or more," said Julie Meredith, WSDOT SR 520 program director.

The damage was discovered May 11th after construction crews completed post-tensioning on a longitudinal pontoon measuring 360 feet long, 75 feet wide and more than 28 feet tall. Crews plan to de-tension the steel tendons, remove concrete and add steel rebar reinforcement needed to contain the steel tendons. 

WSDOT and contractor KG are focused on making the modifications carefully and swiftly, but say it is too early to say how much the repairs will cost or how costs will be assigned.

Pile Driving Begins on Pontoon Construction Site in Aberdeen

ABERDEEN, Wash. - The sounds of progress start echoing through the State Route 520 Pontoon Construction project site this week as crews begin to drive hundreds of support pilings to form the foundation of a pontoon casting facility.

The Washington State Department of Transportation (WSDOT) and contractor Kiewit-General (K-G) are constructing the foundation for the casting basin where they will build the concrete pontoons that will form the backbone of a replacement SR 520 floating bridge. Crews must drive as many as 900 steel piles 125 feet into the ground. During the three-month process, K-G will have up to 20 pile drivers working at the site, and nearby residents and businesses will notice hammering sounds.

“This work is critical in that it literally lays the foundation for the pontoon construction that will start later this year,” said Dave Ziegler, WSDOT principal engineer. “As we finish sections of piles, we’ll begin excavating the site to create the basin.”

WSDOT Begins Fieldwork on Pontoon Project at Port of Tacoma

SEATTLE – 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, safer 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.