Pierce County officials have added the nearly 60-year-old Fox Island Bridge to their list of bridges that need replacing after an underwater inspection discovered holes up to several feet deep in concrete foundation footings.
The discovery led officials to add a “structurally deficient” designation to the 1,950-foot-long bridge, the longest of 141 spans owned by the county.
The bridge now has a sufficiency rating of 7.33 on a 100-point scale, down from 33 last year and well below the threshold of 50 for priority replacement.
But the county has no immediate plans to repair or replace the bridge, which connects Fox Island and its more than 3,500 residents to the Gig Harbor Peninsula.
The estimated replacement cost is $50 million to $60 million.
Kraig Shaner, the county’s bridge engineering supervisor, said the bridge is safe. He said the footings are stable, and the bridge’s foundation isn’t compromised, despite gouges found in all 12 of the bridge’s piers with concrete footings.
“They’re not catastrophic, but they’re something we want to track and watch and see if it’s getting worse,” Shaner said.
“Structurally deficient” means a bridge’s condition or design reduces its ability to carry its intended load. The Fox Island Bridge already had posted weight limits and is designated “functionally obsolete” because it is only 22 feet wide from curb to curb.
Replacement of the bridge could still be as many as 20 years down the road, depending on the availability of federal funding, Shaner said.
But given the hefty price tag, he said the county needs to start planning to replace it as soon as possible.
Shaner made that recommendation during a status report last week on the county’s bridges. The County Council requested the report after the Interstate 5 bridge over the Skagit River collapsed in May.
The two-lane Fox Island Bridge was constructed in 1954, replacing a ferry that ran eight times a day and attracting growth from the mainland.
Today it is one of the county’s busiest bridges, handling 6,400 vehicles per day. The speed limit is 35 mph for cars and 25 mph for trucks.
Fox Island had a reported 3,633 residents at the time of the 2010 Census.
An underwater inspection of the bridge completed by the state’s bridge preservation office last year revealed the holes in the footings. The state did the work from July to October and issued its report to the county in November.
In December, public works and utilities started talking about the need to replace the bridge, Shaner said.
The inspection found gouges ranging from 9 inches to 6 feet deep extending several feet into the face of the underwater footings.
The steel-reinforced footings — one per pier — are massive. The biggest gouges were found on footings larger than the bridge’s original design called for, he said.
“In the grand scheme of things, there’s still a whole lot of concrete there,” Shaner said.
Even so, the state has downgraded the bridge’s substructure from a satisfactory rating of 6 to a poor rating of 4, on a scale of 0 to 8.
The holes could have occurred during construction or could have developed over time, Shaner said.
Most of them are 1 to 2 feet deep.
“It doesn’t go all the way through, and it doesn’t go all the way around,” Shaner said.
The bridge preservation office had noted less specific “voids” or holes in some footings in prior inspection reports, he said. The latest inspection was much more detailed.
Besides the 12 piers with holes in their footings, eight other piers on the approaches to the bridge are in good condition, Shaner said.
The state Department of Transportation recommended that underwater inspections continue every five years. It didn’t recommend immediate repairs but said the county should start planning for potential repairs, which would cost millions of dollars, Shaner said.
If the holes are worse in five years, the county might start working on plans to repair the bridge, he said.
Fox Island resident John Ohlson has driven the Fox Island Bridge since 1979 and was surprised to learn it needs to be replaced.
If the county had to close down the bridge or repair it, he said, that would “definitely cause a great deal of hardship for the residents of the island.”
But Ohlson, who has worked in construction, said he’s not alarmed by the discovery of gouges.
“A big chunk of concrete — even though it has a hole in it — still has a significant amount of structural integrity,” Ohlson said. “I’d be comfortable driving on the bridge.”Steve Maynard: 253-597-8647