Geophysical Technologies for Detecting Underground Coal Mine Voids:
An Interactive Forum
Using Helicopter Electromagnetic Surveys to Identify Flooded Workings in Underground Coal Mines
Presenter: Richard Hammarck
Mailing Address: P.O. Box 10940
Pittsburgh, Pennsylvania 15236-0940
The U.S. Department of Energy's National Energy Technology Laboratory (NETL) has used helicopter-mounted electromagnetic (HEM) surveys to identify mine pools within active and abandoned underground coal mines in the eastern United States. Currently, two types of HEM surveys have been tested: frequency domain electromagnetic surveys (FDEM) and time domain electromagnetic surveys (TDEM). Preliminary results of this evaluation indicate that FDEM surveys can identify flooded mine workings in areas where overburden is less than 50-m thick. In areas of thicker overburden, TDEM may be preferable. A demonstration of TDEM for the detection of deeper mine pools is currently underway.