Here’s where it stands now.
MARION COUNTY, Iowa — The Marion County sinkhole is becoming a growing eyesore. It first appeared last year, then re-opened in June.
Local 5 was there checking out the scene in early June. Back then, the hole didn’t even touch the road. Now, it covers the entire width of the roadway.
Needless to say, the road is still closed.
Retired Iowa State professor Bill Simpkins explained the basics of how sinkholes work to Local 5.
“Any place that you have a rock that will dissolve and water gets to it underground, you can basically dissolve a big hole and then the top will fall in,” he said.
That hole starts underground, invisible to passersby and can take hundreds of years to reach the surface then causing the collapse, said Simpkins.
And rain or adjusting rocks can cause sinkholes to grow.
“Usually a sinkhole does not stay the same size. The tendency is for them to expand until there’s some limit, you know, laterally, where it can’t get any bigger and that might be constrained by a different rock type,” Simpkins said.
The Iowa Department of Agriculture and Land Stewardship determined that a nearby limestone mine operated by Bruening Rock Products caused the original sinkhole.
The agriculture department sent Local 5 the following statement:
The Mines and Minerals Bureau within the Iowa Department of Agriculture and Land Stewardship issues licenses and registrations to all the mineral mining facilities in the state. We also have experience managing underground coal mine subsidences (sinkholes) and reclaiming abandoned surface coal mines. When this sinkhole formed last spring, our team worked with Marion County to investigate the cause of the sinkhole. If a sinkhole is determined to be caused by a historic coal mine, we have financial resources at the Department to help remediate it. However, in this case, the investigation determined the cause was as a result of a limestone mine operated by Bruening Rock Products. The company is then responsible for fixing the subsidence and backfilling the hole. Unfortunately, those closure efforts turned out to be inadequate as the sinkhole has now returned. It is our understanding that the company is now working with an engineering firm to fix the situation. Our team at the Department is available to provide additional technical assistance as needed.
According to Marion County engineer Tyler Christian, this isn’t the county’s first sinkhole.
In fact, in 2009, a limestone mine-related sinkhole formed just half a mile away on the road.
He said there was a coal mine-related subsidence five to ten years ago that impacted county roads. However, it wasn’t anywhere near the current sinkhole.
Read More: The Marion County sinkhole is growing