Special Report: Into Duluth's Tunnels

Posted at: 11/13/2013 7:22 PM
Updated at: 12/11/2013 3:35 PM
By: Alan Hoglund

All over the city where you live, is infrastructure you depend on, but will likely never see. In the City of Duluth some of it is more than a century old.

The flooding of 2012 is making upkeep and repairs a bigger job. To see the damage firsthand and close-up, Todd Carlson and Tom Johnson, both city employees, lead us inside two of Duluth's biggest storm water tunnels.

The Chester Creek tunnel entrance is located around 13th Avenue East and Superior Street. Carlson told us carries rain and runoff about 700 feet under Superior Street, London Road, and the interstate to the shore of Lake Superior.

We enter carrying flashlights and oxygen meters. Carlson said "that's our safety measure. We use them every time we enter."

The 14-year city worker said, for example, fuel spilled up the creek could quickly flow downstream and make the atmosphere in the tunnel dangerous. While graffiti on the walls shows plenty of people have been inside, he doesn't recommend you enter any tunnel in the city because of the risks.

Carlson said initial construction started around 1910. At about 12 feet in height, the Chester Creek tunnel shows its age like rings on a tree. A change in the building material can mean the time period the section was built is different as well.

According to Johnson, the art of building tunnels like this one is long gone. "You look around at this old construction and the methods of stone and brick there is nobody that really does that anymore."

While the monstrous pipe to the lake was built more than a century ago, Carlson and Johnson told us it is fully functional.

During our interview with Johnson in the middle of October, he said "just within the last couple of weeks we had staff down here doing an inspection."

But around midway through it was apparent some things need fixing.

Pointing his flashlight upward, Carlson said "the water started to push the tunnel up here because we had an obstruction right there."

We had stopped where the tunnel passes under the Armory. The force of the high water during last year's flood event lodged branches, logs and concrete in what's left of the ceiling.

Carlson and Johnson told us the tunnel was filled to the top with water - something that hasn't happened since. They said during a typical storm, water will only reach levels a few feet high.

Looking through the massive hole in the tunnel ceiling we could see sunlight. Carlson said we were looking out one of the windows of the Armory's basement. On the other side was the traffic on London Road.

During our interview a few weeks ago, Carlson was unsure about when the damage might be repaired. He said "it is not an urgent fix but it's something that needs to be fixed."

But on Tuesday the Duluth City Council approved an almost $800,000 repair plan. Also getting the OK was about $50,000 more dollars to fix an even bigger, older, and longer tunnel about four miles away.

Starting near Third Street, Miller Creek dips below 26th Avenue West. "This one must be a quarter mile [long]," Carlson said.

"This is a unique tunnel," Carlson said. "It's a little bit bigger than the other one."

Five or six years ago, Carlson said the tunnel, which carries water to the Harbor, got a new concrete floor. It's equipped with a foot-deep channel running through the middle to allow the trout to swim through.

"I have actually seen a fair amount of fish move through this area," he said.

Flood damage isn't as visible in this tunnel but some debris remains, including a truck tire, branches and a big stone. Carlson said "a full fridge was up there. We had to have that removed."

He said there are more than 400 miles of storm water pipe underneath the City of Duluth.

Johnson said "I would say 30 percent is in rough shape." They said when repairs are made to infrastructure like the tunnels depends on many factors, one of which is the number of people affected.

"A storm sewer that crosses through the downtown section is a higher priority than a failed culvert on a one way street in a rural part of town," Carlson said.

While it has been almost 1 1/2 years since flooding damaged the Chester Creek tunnel under the Armory, it's not affecting anyone, because for now, the building is vacant.

So what does the storm water system look like overall?

When we asked Carlson whether a lot of it needs repair, he said it's a tough question to answer. "An emergency repair, no. Does it need to be repaired in the next few years, yes. Will some of it last 10 years, yes. Will some of it last 50, yes."

In a program rolling out next year, Johnson said the city will rate all the pipes in the storm water system. He said it will help them better time when certain sections need replacing.

It will all eventually need help, some parts sooner than others. And most of it is invisible to the people at home who depend on it.

Carlson said "all the infrastructure we have is underground. It's out of sight and out of mind."

While it won't be cheap, the tunnels, and the rest of Duluth's infrastructure have to be ready for another flood should it ever come.