Image: From GreenBayPressGazette.com

Early indications are that the settlement of the pier at the Leo Frigo Bridge in Green Bay, Wisconsin is the result of corrosion of the piling that supports the pier.  Randy Post over at Geoprac.net  has a post up with video and a link to this story in the Green Bay Gazette Press.  From the story:

Corrosion of steel pilings below a support pier on the Leo Frigo Memorial Bridge in Green Bay caused Pier 22 to buckle last week, creating a long, deep dip in the bridge deck and forcing the bridge’s indefinite closure.

The 100-foot-long pilings under the pier were degraded from a combination of water and the composition of soil surrounding the bridge support, Wisconsin Department of Transportation officials said Thursday.

It appears that the suspect piers are in an area of fill, the composition of which may be contributing to the corrosion of the piles:

The investigation is focused on the area from the Fox River east to North Quincy Street on the east side of the bridge, where fill materials like foundry sand and organic materials are part of the soil profile.

“We’ve encountered all kinds of different things,” Buchholz said about soil samples in that area.

In addition to investigating the cause of the settlement of the pier, the bridge has been inspected by the Wisconsin DOT and is not in danger of collapse.  As a precaution, the bridge remains closed during the investigation.