JACKSON, MI (WILX) -- There are a lot of things that contribute to Michigan's lousy roads like weather, heavy trucks, and a lack of money. Now you can add coal mines to the list.
Samuel Sorenson, a construction engineer with the the Michigan Department of Transportation (MDOT) said that they knew there were coal mines in the area when they developed the plans for I-94 and Cooper Street, but to not look at the area where the eastbound exit ramp was located ultimately came down to a cost-saving decision.
After completing the new eastbound off-ramp three-and-a-half weeks ago, MDOT realized there was a crack in the pavement. An 8 to 12-inch settlement, or sinking, was found.
They drilled 66-feet below and discovered a void that was most likely related to a century-old coal mine.
"This interchange has been over these mines for well over 50-60 years and there's only been one known settlement near the westbound interchange," Sorensen said.
MDOT had nearly $4 million set up to fill in mine voids around the I-94 bridge, but Sorensen said that it would've been far more expensive to fill-in the possible voids outside the perimeter the experts had recommended.
The engineer said that if they had included the entire project which includes the eastbound off-ramp, the project would've been tens of millions of dollars.
"From a financial stand-point, it wasn't easy to drill numerous holes and hope to get all of the voids."
Sorensen said that before they found the void, they did listen to consultants when they recommended putting a blanket of geotextile fabric in the area of the eastbound off-ramp which he said may have helped minimize the overall settlement in the area.
Crews will now have to fill the underground void with grout and replace the damaged pavement and drainage system. The cost of repair is between $50-to $100,000, but Sorensen said that they're still in line to stay under budget for the overall project.
The work will delay the opening of the eastbound off-ramp until mid-September, per MDOT.
Sorensen said that they'll be monitoring the road for settlement for years to come and they'll research the best course of action to take if there's another one.
You can find more information about the I-94 project, including photos of the construction progress by clicking here.
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