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Indiana Department of Natural Resources

Indiana Department of Natural Resources

Reclamation > Indiana Coal > Mining Process Mining Process


Mining may not take place until a permit is issued by the Division of Reclamation.  Learn more about the Division's permit process.

Topsoil Removal and Storage is the first stage of mining.  The mining operation plan shows how the soil will be removed and where it will be stored on the permitted site so that it can be replaced during reclamation.  The topsoil is "stockpiled" and protected from erosion with a grass mixture.  Sometimes the topsoil is removed ahead of the mining operation and immediately trucked back to a mined area that has been covered with overburden and ready for final covering and re-vegetation.

Topsoil depth must be determined before mining to assure proper replacement for growing row crops or other vegetation identified in the mining reclamation plan such as trees.  The replaced soils on areas designated as prime farmland must be at least 48 inches of topsoil and subsoil. 

Overburden is removed after the topsoil.  Often this rocky material must be blasted and may also be stockpiled until it can be trucked back to the pit after the coal is removed.  Overburden may contain layers with pyrite which when exposed to air and water can produce acid.  Operators must thus control water during mining so acid runoff is captured in ponds and not allowed into adjacent waterways.  When the overburden is buried back in the pit, any pyrite is mixed with neutral materials and its exposure to oxygen is blocked so it will not leach acid into surface or underground water systems.

The subsoil layers are placed on top of the graded rocky overburden to assure that a suitable rooting material is available for cropland production.  Any toxic overburden must be treated or covered with an adequate layer of nontoxic, noncombustible material.

Mining Plans detail how the coal operator plans to mine and reclaim the site.  These plans are submitted as part of the permit application.  The coal operator describes how soils and overburden will be removed, stockpiled and replaced after the coal is mined.  The types of vegetative covers to be used on stockpiles and after reclamation are identified.  Post-mining land uses are explained in the reclamation plan.  The coal operator gives a timetable for completion of each step and an estimated cost for reclamation.  The operator must bond his permitted operation as assurance that all applicable laws are complied with; otherwise, not only will the permit be revoked but also the bond used for reclamation.

Protection/Restoration of the natural resources before, during, and after mining are closely regulated. Learn more information on how these resources are protected. You may find additional information under the "Protect Resources" button on the Division's Homepage.

Reclamation begins with rough grading of the mined overburden back into the pit.  Rough grading must be done within 180 days of coal removal.  There may be no more than four un-graded spoil ridges behind the active pit unless a temporary variance is approved due to unusual conditions such as weather, equipment failure, or other conditions.  When this first phase of reclamation is completed, restoring the land to its approximate original contour, part of the operator's bond can be released after inspection by the reclamation specialist.

Materials from the initial pit or box cut must be graded to blend with un-mined land.  Final grading must be completed in a timely manner, usually in time for the next growing season.  This includes any subsoil or topsoil replacement and installation of erosion control measures such as terraces, diversions, grass waterways, and drains.  To ensure the soil will support vegetative growth, the operator tries to use equipment that will minimize soil compaction.  Most plans specify a crop of wheat or oats followed by a grass-legume mix that helps restore soil structure and bacteria needed for good plant growth.  When the land has been re-vegetated, the operator can request release of the next portion of bond.

Reclamation ends when vegetation is fully established in accord with the post-mining land use plan.  Additionally, operators must establish row crop production on prime farmland areas.  Field test plots are the most common method used to verify vegetation growth.  A count of vegetation covering the ground is used on land uses other than row cropland.  For trees, it is 450 trees per acres that have shown evidence of satisfactory growth for three years.  A five to ten-year vegetation liability period begins when all grading is completed and the land is planted to a crop capable of supporting the post-mining land us. At this point, final bond is released and the permit terminated.

Award winning reclamation is not unusual by today's mining standards.  Many Indiana operators have won national acclaim for their innovative reclamation work.  The days of abandoned mine lands and unproductive spoil ridges or acid water have been replaced by conscientious attention to the environment.  Indiana has a viable coal resource that will provide many years of energy supply to public utilities while ensuring that coal mined lands return to a capacity that will also be productive well into Indiana's future.