Published in American Longwall Magazine
Earlier this year the Mine Safety and Health Administration (MSHA) awarded a $283,777 contract to energy and mineral resources group Marshall Miller & Associates to demonstrate the use of in-seam seismic technology for locating both air and water filled mine voids from an exposed coal seam outcrop.
The contract was awarded as part of a $10 million appropriation to detect mine voids and digitize mine maps in the wake of the 2002 inundation at the Quecreek mine in Somerset, Pennsylvania.
Marshall Miller, together with TECO, the Virginia Department of Mine, Minerals and Energy, and Virginia Tech, will uncover Sassy No.1 mine’s Splashdam seam outcrop adjacent to an existing mine void, perform verifiable surveys of the underground mine works and surface, and conduct a seismic survey.
“Safety is an important feature of this work that will assure continued mining operations will not result in exposing mine workers to areas previously mined and unmapped. Additionally, when locating and designing refuse impoundment areas on the surface, seismic surveys will assure mine operators can accurately locate previously unmapped mine areas,” Marshall Miller & Associates said.
The now idle Sassy No.1 mine was chosen for its accessibility in performing an accurate underground survey. The mine has both dry and flooded workings, accessible outcrop locations, and existing survey controls in place on the surface. TECO was in full support of the project.
Seismic technology works by generating an energy wave in the seam which propagates until it contacts a discontinuity such as a void or a fault. The wave reflection is measured at receivers also placed in the coal seam.
A seismic survey, utilizing the in-seam method, is capable of detecting both flooded and dry areas of the mine void. The sensitivity of the in-seam technology and its ability to detect mine voids is subject to geology and other subsurface features. There is no adverse environmental impact with in-seam technology.
Marshall Miller’s fieldwork will be completed by the end of the year and interpretation of the data is expected to take eight months. Interpretation will be carried out by Virginia Tech’s Dr. Matthias Imhoff and Marshall Miller. During this process the data collected will be shaped using the latest computer modeling technology and an image will be produced which accurately depicts the mine voids in both flooded and dry areas.
The end result of the work will be a documented procedure which can be used by the mining industry. A final report to MSHA is expected by November 2005.
