ABERDEEN – 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.”
The cylindrical piles are 18 to 24 inches in diameter and measure 140 feet long. Laid end to end, the 900 piles would stretch nearly 24 miles. The facility must be capable of supporting the weight of six massive concrete pontoons per cycle – estimated to weigh a combined 50,000 tons, including four large pontoons weighing 11,000 tons each.
“It might seem like this a tremendous amount of pile we are driving here, but this foundation must be solid enough to support the concrete casting basin and pontoon production,” said Phil Wallace, K-G project director. “Getting these piles in place keeps us on track to open the facility by the end of the year and finish the pontoons in 2014.”
WSDOT and K-G will construct 33 pontoons at the site to replace the aging SR 520 bridge. Of these, 21 will be the largest pontoons ever built in the state and will be as long as a football field.
In January 2010, Kiewit-General was awarded the $367.3 million project to construct the casting basin facility, including a concrete batch plant and the new SR 520 bridge pontoons.
For more information about the SR 520 Pontoon Construction Project and to view project photos, visit www.wsdot.wa.gov/Projects/SR520/Pontoons