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Ongoing care for water quality is one aspect of Red Wing Bridge project

Mark Anderson

Mark Anderson is the MnDOT construction project manager for the Red Wing Bridge project. He can be reached at 507-205-6402 or mark.w.anderson@state.mn.us

Have you seen large blue containers around our construction site, especially on the Minnesota side of our work zone? They perform a special duty for our project and in the process are keeping the Mississippi River clean.

During the work leading up to construction, we took tests of the soil in the area to determine if there were any contaminants. Results ranged from chemicals to petroleum products depending on what was on the land previously. In one case, there was an old gasification plant on the site near Barn Bluff in our construction zone and the soil testing detected oil, petroleum and slag from the plant.

And that's where the tanks come into play.

As we dig in the soil and remove water or use water during the work, we pump it into the tanks, where it is treated through a series of tanks. This ensures that any water that has passed through the soil or been in contact with contaminated soil is treated before it is put back into the sanitary sewer system. We could have tested the water to determine what water was contaminated and needed treatment and what wasn't, but didn't. Instead, we decided to treat all water as contaminated to ensure there were not mistakes in making that determination.

We have worked with the city of Red Wing's water treatment plant to verify the results and be sure that the water met its quality levels. They have tested it to be sure.

On the Wisconsin side, water is pumped through a filter bag to filter out the sediment during the work and is allowed to then flow back into the waters. When the contractor is drilling shafts for the piers and doing the work for cofferdams, the water is moved to a tank and neutralized with carbon dioxide, which reduces the pH, then it's filtered and eventually returned to the river.

If you drive by a bridge construction project of this size your focus is likely on the towering cranes, the earth moving equipment and all the workers in hard hats. That is the core of the work, but it's important to note all that goes into these projects and the care we give to water and the environment in which these bridges are built.

Work won't stop because of colder temperatures or the winter season. If you want to look ahead, here's what you might see:

• Curb and gutter, and paving on Bluff Street. We're also hopeful that pedestrian ramps at Third and Plum will be completed. We would like to get curb and gutter and temporary paving on Third from Plum to Potter done, but as with all work, it will depend on what the temperatures are for this but I don't know if it will happen with the forecasted temperatures.

• The last drilled shaft was poured on Monday, Nov. 5. There should be a lot of activity on Pier 1 for the next two months. Zenith Tech Inc., our contractor, will also be working at Pier 2. They will also continue on retaining walls around the project.

This $63.4 million project is a strong partnership that includes the Wisconsin Department of Transportation, the city of Red Wing, the Federal Highway Administration and Zenith Tech.

As part of team's efforts, you will see City Engineer Jay Owens and me together at various community events or on a bridge tour. We'd be happy to visit with your group or provide your organization or business with the necessary information about the project so you can keep your employees informed. We've found that if you know more about the project, you can help others understand it and minimize any possible disruptions it might cause. We do regular updates on the Community Access Channel 6, so you can catch us there as we provide updates and field questions.

We have a lot of good information that can help explain the project. You can learn more about the project or sign up for email updates by going to MnDOT's project web site www.dot.state.mn.us/d6/projects/redwing-bridge/ or you can follow us on Facebook athttps://www.facebook.com/RedWingBridgeProject/.

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