Is your home over a mine? Check this map to find out

Newcomers to the metro-east might be surprised to hear the region is riddled with dozens of abandoned coal mines.

To find out if your home or business is located over a coal mine, you can type your address into an interactive map produced by the Illinois State Geological Survey. If you see large cracks in your sidewalk, driveway and/or walls in your home, you may have a problem known as “mine subsidence,” according to the Illinois Mine Subsidence Insurance Fund.

The Illinois State Geological Survey map shows that Wolf Branch Middle School at 410 Huntwood Road is on the edge of an undermined area in Swansea. On Monday, Wolf Branch School District officials said cracks in walls and buckling of floor tiles have been found in the middle school.

The Illinois Department of Natural Resources Office of Mines and Minerals began investigating the Wolf Branch site on Monday and has determined that “sag subsidence is impacting an area of about 3 acres,” according to agency spokesman Ed Cross.

Sag subsidence is the most common type of mine subsidence and “appears as a gentle depression in the ground and can spread over an area as large as several acres,” according to the Illinois Mine Subsidence Insurance Fund. This sagging in the ground is usually caused by the collapse of pillars supporting the mine roof, the insurance fund reports.

Scott Elrick, head of the coal section of the Illinois State Geological Survey, said his agency’s interactive map will help Illinois residents who have this basic question: “Is there a mine underneath me?”

Elrick, who was part of the team that produced the interactive map, recommends the map for anyone who is “curious” about underground coal mines.

“The lofty goal is to be the definitive work on the underground coal mines in Illinois,” Elrick said. “That’s the goal.”

Elrick is not investigating the Wolf Branch case but he said the damage reported is “certainly a warning sign” that mine subsidence has to be considered based on the location of the school near the Summit Coal & Mining Co. mine that was in operation from 1894 to 1940, except for two years during the 1930s.

Homeowners who suspect their home has been damaged by mine subsidence are encouraged to contact their insurance agent, said Kathy Moran, manager of industry relations and consumer education for the Illinois Mine Subsidence Insurance Fund.

“The way mine subsidence can work, though, is one homeowner might experience damage and the neighbors on both sides may have none,” Moran said.

The Illinois Mine Subsidence Insurance Fund is a non-government organization but it was created in 1979 by the General Assembly with the support of several metro-east lawmakers. The purpose of the fund is to help people pay for repairs when their property has been damaged by mine subsidence.

In the past four years, the fund has received an average of 350 claims per year but most of the claims are determined to not be related to mine subsidence. Moran said St. Clair County has the highest number of confirmed mine subsidence cases in the state.

Here is some information the insurance fund offers Illinois residents:

Q: How much does mine subsidence insurance cost?

A: The premium for a home worth $100,000 is $44 annually and the premium for a $200,000 home is $71.

Q: Is mine subsidence insurance required?

A: By statute, all insurance companies must provide coverage of mine subsidence. In 34 counties where most of the state’s underground mining has occurred, including Madison, St. Clair, Clinton, Bond, Washington and Randolph, state law requires mine subsidence to be included in both residential and commercial policies. However, the property owner can reject the coverage in writing.

Q: Where can I go to get more information about mine subsidence before I buy a house?

A: The fund’s website at www.imsif.com is full of reports, brochures and a video to help homeowners navigate this issue.

Is your home undermined? Check with this interactive map

This story was originally published September 12, 2017 at 4:07 PM with the headline "Is your home over a mine? Check this map to find out."