Every ship that passes under the Duluth/Superior harbor lift bridge is a sign of a healthy, working, international port. but for this to exist, requires steel. Nearly 14-miles of underwater metal.
Loading facilities, docks and shorelines, the shipping canals; the very foundation of industry here is built on an underwater steel infrastructure. But it’s corroding, and failing.
It’s falling victim to an aggressive form of fresh water corrosion.
Chad Scott is with an engineering company based in Superior. He first discovered the unique form of corrosion back in 1998 and brought it to the attention of the scientific community.
Today, his focus has turned to helping repair the harbor and protect it from further damage.
“There were a couple of projects in the harbor we were called to inspect that had already completely failed. They had gotten so thin and with the forces on them, the steel actually bent so you can’t repair it at that point,” Scott said.
Replacing all the steel in the harbor would be a monumental task, taking years and costing hundreds of millions of dollars. But does it all have to be replaced? Not necessarily, if the corrosion is caught early enough.
It also depends on individual docks. There are some docks that have actually commenced replacement projects and there are other ones that have gone through protective procedures.
Good news for the port, because it owns such a large amount of steel shoreline. Last summer they repaired this entire dock line, a $6 million fix.
From federal to local, that effort includes UMD’s Biology Department, and Dean Dr. Randall Hicks. Dr. Hicks says it’s a multi-agency battle because there are global implications.
“Corrosion is a major problem world-wide. it’s responsible for huge economic losses and there’s a lot of effort put in to try and prevent corrosion, even on your cars with better primers and paints. The problem is in a harbor you have steel that’s submerged and it’s very expensive to replace it or to mitigate the problem.”
Dr. Hicks said we are beginning to understand the problem. But in order to find real, long term solutions, additional research needs to be done. and research takes money.
“We are doing our best to gather as much information as we can so we can keep the study moving forward. But without additional funding it’s not going to go forward.”
The short term goal is to save the steel that can still be saved. Long term, researchers hope new alloys and materials will be developed for future construction that can stand up to this aggressive corrosion.
Divers have been measuring corrosion rates over the last two years, both in and outside the harbor. It’s research that may not only help us, but ports around the world.