Mechanical, Electrical, Geotechnical

Coal Mining Equipment Damaged from Cave-In

28 February 2022

Envista was called in to investigate the nature, extent, and cause of loss to a continuous mining machine that occurred following a cave-in at a coal mine in the Midwest United States. Envista’s Civil/Structural and Mechanical engineering teams conducted an on-site investigation, which consisted of an inspection of the pit mine and underground mining area. 

Following a discussion with the insured, it was determined that while boring through the earth in an underground coal mine, using the room and pillar method of mining (a method where layers of coal are partially mined, leaving large pillars of coal intact to support the overlying layers of rock1), at about 100 feet down into the pit and 800 feet of boring through the sidewall, a cave-in occurred. 

In a typical continuous mining machine, the continuous miner cuts a three by nine-foot path in the sidewall of a pit and uses conveyor cars to remove the coal to the pit. After the cave-in occurred, the insured made several attempts to pull the continuous miner and conveyor cars out of the mine, but they remained unsuccessful. 

Discussions were then had to bring in Envista’s Geotechnical team to investigate the cave-in from above, along with using a robot to go into the mine to confirm the cave in. Envista’s team considered bringing in a drone or track robot, but this was not finalized, as the insured made the choice to stop pumping water from the pit, flooding the pit, and rendering further discovery from happening.

Following Envista’s inspections and review, our expert team was able to confirm that several miner and conveyor cars became stuck inside the mine due to a coal wall and ceiling cave-in and that the cave-in was unavoidable. In addition, the miner and conveyors could not be removed from above without disturbing the watershed land above, which was regulated by the Department of Natural Resources (DNR) of the state. They deemed the wetland above to be inaccessible for any use, as it was delineated as a protected wetland. Replacement of the machine was approved, but only at Actual Cash Value (ACV).

1 Room and Pillar Mining - an overview | ScienceDirect Topics

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About The Author
Keith Nygaard
Keith Nygaard
Principal Consultant

Principal Consultant With over 20 years’ experience, Mr. Keith Nygaard provides consultation to the insurance and legal communities in matters of multiple types of losses in multiple industries involving design, manufacturing and project management and over 12 years in the insurance industry. At Envista, Keith provides electrical, mechanical and forensic engineering evaluation along with origin and cause investigations for equipment and machinery failures and fire investigations in the USA, Canada and Asia. Additionally, he is highly knowledgeable in contamination losses and restoration processes relating to high tech equipment. Some of his projects have involved manufacturing plants, hospitals, universities, power plants, city and government facilities and construction sites. 

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