Evaluation of management options for intermine flow and associated impacts in the Central Witbank Coalfield
| dc.contributor.advisor | Usher, B. | |
| dc.contributor.author | Hough, J. J. H. | |
| dc.date.accessioned | 2018-04-04T08:43:23Z | |
| dc.date.available | 2018-04-04T08:43:23Z | |
| dc.date.issued | 2003-07 | |
| dc.description.abstract | English: Research into the identification, quantification and impact assessment of the intermine flow on the groundwater and surface water quality of the Witbank and Highveld coalfields was undertaken as part of broader research initiatives The study area of this thesis included the coal collieries of the Central Witbank Coalfield. Intermine flow areas were previously identified in studies by Grobbelaar et al., 2001 and Grobbelaar, 2001. The aim of this thesis was to develop a quantitative prediction of long-term intermine flow in the central Witbank coalfield, using the available data collected in the project. From the quantification of these flows and different hydrochemical techniques, likely water quality profiles at these collieries were determined. The quantification on the intermine flow direction as well as the flow volume was predicted through numerical groundwater modelling using Modflow. Local and regional models were compared and it was found that regional models (relative to including the whole extend of the voids in the model area) yielded the most accurate answer of the two models in the study area. The quantification of the predicted impact on water qualities was done through the use of mass balance approximations and an empirical sulphate generation rate method (developed in this study for predicting future sulphate concentrations in underground workings) using available hydrochemical and acid base accounting data. It was calculated that the sulphate generation rate for the underground workings is in the order of 0.1 - 1.5 kg/ha/d depending on the degree to which the void is filled. An evaluation of water management strategies, which will minimise the long-term influence of intermine flow on the groundwater and surface water quality, was also done. A compartmentalization system to mining opencast pits has been suggested for opencast pits with low decant elevations, to inundate a maximum percentage of the spoils to limit AMD reactions. The implementation of artificially created, high recharge areas on opencast pits and underground workings also was investigated to reduce fill-up times of voids as to limit the exposure of oxygen to the acid generating materials. The research indicates that intermine flow can be potentially detrimental to the groundwater- and surface water systems depending on the flow volumes and quality of the intermine flow water in the Central Witbank Coalfield. Flow volumes predicted through numerical modelling was quantified to be considerable enough to be potentially detrimental to mining voids into which the intermine flow water flows. It was also found that the intermine flow could influence the fill up times of the mining voids (both opencast pits and underground workings). The evaluation of different management options identified viable alternatives to manage intermine flow in such a way as to yield future optimal water qualities for the Central Witbank Coalfield. | en_ZA |
| dc.description.abstract | Afrikaans: Navorsing is gedoen om moontelike areas van inter-myn vloei te identifiseer, te kwantifiseer en om die impak daarvan op die grond- en oppervlak water te bepaal. Die studie area sluit die steenkool myne van die sentrale Witbank steenkool veld in. Meeste van die inter-myn vloei areas was deur Grobbelaar et al., 2001 en Grobbelaar, 2001 vasgestel in vorige studies. Die doel van die studie was om kwantitatiewe voorspelings tegnieke en metodes te ontwikkel om die lang termyn impak van inter-myn vloei te bepaal deur die gebruik van bestaande data. Deur middel van die kwantifikasie en verskeie hidro-chemiese tegnieke is verskeie moontlike hydro-chemiese profiele vir die tesis bepaal. Die kwantifikasie van die inter-myn vloei is bepaal deur numeriese modellering, deur die gebruik van Modflow. Daar is geëksperimenteer met lokale en regionale grondwater modelle en dit is bevind dat die regionale modelle meer akkurate antwoorde lewer. Die kwantifikasie van die impak op die grondwater en oppervlak water is bepaal deur die gebruik van massa balanse, die empiries sulfaat generasie metode (ontwikkel vir voorspeling van sulfaat konsentrasies in die ondergroundse werke) en ander hidro chemies tegnieke, deur die gebruik van bestaande data. Dit is bepaal dat die sulfaat generasie tempo in orde van 0.1 - 1.5 kg/ha/d gekoppel aan die mate wat die ondergrondse werke gevul is met water. "n Evaluasie van sekere grondwater bestuurs stratigieë is gedoen om die lang termyn impakte van inter-myn vloei te beperk op die grondwater en oppervlak water bronne vir die studie area. In die tesis is "n stelsel van kompartimentilisasie voorgestel vir oopgroef myne met "n lae "decant" elevasie om sodoende die maksimum persentasie van die "spoils" onder water te hou om sodoende die suur generasie reaksies te beperk. Die implimentasie van verhoogde grondwater aanvullings areas om sodoende die ondergrondse werke sowel as die oopgroef seksie vinniger met water te vul om die blootsteling van suur produserende materiale aan suurstof te beperk. Die navorsing toon dat inter-myn vloei potensiaal skadelik vir die grond- en oppervlak water kan wees, afhangende van die inter-myn vloei volumes en kwaliteite van die inter-myn vloei waters. Deur numeries modellering is vasgestel dat die vloei volumes groot genoeg is om potensiaal skadelik te wees vir die myn werke wat in die inter-myn vloei waters invloei. Dit is ook bevind dat inter-myn vloei die opvul tempo van die mynbou werke beinvloed. Deur evaluasie van sekere bestuurs stratigieë was dit bevind dat daar wel sekere bestuurs stratigieë is wat geimplimenteer kan word om optimale water kwalititeite te verseker in die toekoms. | af |
| dc.identifier.uri | http://hdl.handle.net/11660/8096 | |
| dc.language.iso | en | en_ZA |
| dc.publisher | University of the Free State | en_ZA |
| dc.rights.holder | University of the Free State | en_ZA |
| dc.subject | Coal mines and mining -- South Africa -- Mpumalanga | en_ZA |
| dc.subject | Water quality management -- South Africa -- Mpumalanga | en_ZA |
| dc.subject | Coal mines and mining | en_ZA |
| dc.subject | Dissertation (M.Sc. (Institute for Groundwater Studies))--University of the Free State, 2003 | en_ZA |
| dc.title | Evaluation of management options for intermine flow and associated impacts in the Central Witbank Coalfield | en_ZA |
| dc.type | Dissertation | en_ZA |