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Underground mines have had more than 900 million tons of coal removed in Indiana since the 1800's. In the early days, many mines were never surveyed, thus few maps exist to describe the extent of abandoned underground mines. Geologists estimate that up to 150 square miles of underground coalmines exist in the 26 coal producing counties in Indiana. Property owners may not be aware of an underground mine until it collapses leaving a depression or hole in the ground or causing structural damage to their homes. In the very early days of industry simple hand tools were used to extract coal close to the surface. Shallow seams were easier to extract with the technology of the times. Roof support consisted of simple wooden supports, and the occasional pillar of coal left in place. Over the course of several years these features erode and the roof can crumble. Eventually it may not support itself and collapse completely opening a large hole at ground level measuring several feet across and very deep.
The Restoration Section has been reclaiming abandoned mine lands throughout Southwestern Indiana for more than 25 years. Like any construction operation, this surface work is easily visible as large equipment and workers can be observed eliminating a variety of dangerous and obvious public and environmentally threatening features. Subsidence is different. These conditions are the result of historical underground mining and not as easy to identify. When multiple subsidence events occur in close proximity, a potential solution is to grout the mine void to minimize future ground movement. Additional information on the Division’s grouting projects can be found in the Division of Reclamation Grouting Brochure. These grouting projects focus on public infrastructure, because private property can be protected through mine subsidence insurance. This Grouting stabilization project provides a pictorial look at a grouting stabilization project.
Mine Subsidence Insurance
Conventional home-owners insurance does not cover damage caused by mine subsidence. However, insurance protection sponsored by the State of Indiana is available for home-owners through private insurance agents. In 1986, the Indiana legislature established the Indiana Mine Subsidence Insurance Fund. This insurance covers structural damage caused by old abandoned underground mines. Compensation or repairs for damage caused by active underground mining is the responsibility of the mine operator.
Property owners in the following counties are eligible for this insurance: Clay, Crawford, Daviess, Dubois, Fountain, Gibson, Greene, Knox, Lawrence, Martin, Monroe, Montgomery, Orange, Owen, Parke, Petty, Pike, Posey, Putnam, Sullivan, Spencer, Vanderburgh, Vermillion, Vigo, Warren, and Warrick. Mine subsidence protection can be added when a policy is purchased or renewed. For more information, contact your insurance agent or the Indiana Subsidence Insurance Fund at the Indiana Department of Insurance at 1-800-332-IMSI.
Mine maps are helpful in determining whether an underground coalmine might be located near your property. The Indiana Geological Survey has maps available by calling 812-855-7636.
Documentation does not exist or is not available for many of the smaller underground mines that are scattered throughout southwestern Indiana.
Subsidence that does not affect structures may be covered under the Emergency Section of the Abandoned Mine Lands Program. If you notice damage to your land or adjacent roads and property that you feel might have been caused by old underground works, visit the Emergency Section of the Abandoned Mine Lands Program.
We offer a guide to help the public and local officials further understand potential problems associated with previously mined areas.
These problems may be associated with both underground and surface mined sites and can result in serious damage to improvements.
Previously mined land may have many attractive features for development as residential, industrial and recreational sites.
Hidden dangers such as dangerous mine openings, unstable highwalls, and unpredictable ground movement have resulted in serious damages to improvements on these sites. Additional problems can result from subsidence, mine spoils, mine impoundments, and landslides.
The Indiana Division of Reclamation always suggests obtaining assistance from a qualified engineer for specific site evaluation before you buy or build on previously mined land. A list of resources is provided at the end of this booklet for additional information.