ICGCM Papers:
Fundamental Research Studies
 
 
Evaluation of Potential Impacts to Stream and Ground Water Due to Underground Coal Mining
35th International Conference on Ground Control in Mining
Evaluation of Potential Impacts to Stream and Ground Water Due to Underground Coal Mining
by
Christopher NewmanZacharias AgioutantisGabriel Boede Jimenez Leon, University of Kentucky, Lexington, United States
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[Conference] 35th International Conference on Ground Control in Mining
[Price] Free  [Comments] 0
[Topical Area] Fundamental Research Studies
[Author] Christopher NewmanZacharias AgioutantisGabriel Boede Jimenez Leon, University of Kentucky, Lexington, United States
[Abstract] 
Key Conclusions:
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The work presented in this paper focuses on further developing the SDPS to provide mining and regulatory engineers with the means of more accurately predicting the effect of underground mining operations on surface and subsurface bodies of water. The new Pillar Punching Calibration Routine in SDPS allows a better determination of an increased surface subsidence trough, and therefore ponding potential, due to pillar punching through the determination of site-specific modeling parameters. The hydrogeological feature implemented in SDPS allow industry engineers to more accurately depict mining induced effects on ground water flows through overburden material. Applying these newly developed features in SDPS can aid industry engineers in establishing optimum extraction sequences for underground mining operations for the protection of water sources through more accurate prediction of mining induced deformations and ground water flow magnitudes.
Key Findings:
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Through the implementation of new features to the SDPS program, users are able to better predict the possible effects of underground mining on surface and subsurface bodies of water. Although SDPS capabilities include variable surface topography and yielding or strong chain pillars, the case of weak underlying floor strata was never addressed in detail. More specifically as pillars are further displaced into the immediate floor material, field measurements have shown an increase in the subsidence profile creating larger surface ponding area. A newly developed calibration routine is now available to negotiate the issue of pillar punching and provide a more accurate determination of site-specific subsidence parameters and thus better prediction of surface deformation indices. Overall, SDPS can calculate a number of deformation indices that can be used to establish parameters that may affect the flow of surface water bodies, such as ground slope, potential for pooling due to subsidence, etc. In addition, as the strata deforms in the vicinity of mining operations, there are inherent changes to the hydrogeological properties of the overburden. The principal effect of these mining induced deformations within the overburden is dewatering (Elsworth, et al, 1994). Mining induced stress and strain within the overburden have been previously correlated to changes in the hydrogeological properties of rock and soil (Materic, et al, 1995). Results will be shown of preliminary work performed that ties potential changes to ground water flow parameters to mining.
Objective of the Paper:
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Developed 25 years ago, the Surface Deformation Prediction System (SDPS) software package has been consistently updated with new analysis and prediction features that provide users with a reliable and versatile program for today’s practicing mining engineers. SDPS primarily utilizes the influence function for the calculation of deformations in the overburden due to underground mining with respect to mining geometries, overburden properties, variable topography, etc. The objective of this research is to analyze ground movements due to longwall mining operations which could potentially damage the hydrological balance within as well as outside the mine permit area in the form of increased surface ponding and changes to hydrogeological properties. This paper will present the methodology to calculate surface deformations along linear water bodies as well as a newly developed calibration routine for the prediction of ground movements due to, “pillar punching” which has a direct bearing on surface water protection. In addition alternate procedures for analyzing ground water behavior due to mining induced deformations within the overburden material will be critically evaluated.
Problem Statement:
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Recently, the Office of Surface Mining Reclamation and Enforcement (OSMRE) has completed a public comment period on a newly proposed rule for the protection of streams and ground water from adverse impacts of surface and underground mining operations. These proposed regulations call for an increase in baseline data collection, pre- and post-mining monitoring, mitigation/restoration practices, as well as increased focus on possible mining induced damages to the hydrological balance of the mine permit area. The work presented in this paper focuses on further developments to the Surface Deformation Prediction System (SDPS) to provide users with a means of accurately calculating surface deformations along linear water bodies (e.g. streams), under various underground mining conditions including pillar punching in soft underclays. In addition, a first attempt to quantify hydrogeological changes due to mining activity is attempted by calculating strains at different ground water horizons. Through the implementation of these new features of SDPS, industry personnel have been provided with the means of more realistically predicting the potential effect underground mining operations have on ground and water movement. These features seek to further increase environmental protection through the optimization of underground extraction sequences while maintaining coal reserve production and miner safety.