A new opencast coal mining operation is proposed in the Belfast region in
Mpumalanga, South Africa. This proposed operation is the study site that was
investigated in this thesis. The Belfast opencast operation is expected to be
operational for 29 years and coal from mainly the number 2 and 3 seams will be
mined.
The inflow rate of the groundwater was determined by using both analytical and
numerical groundwater methods. The rate at which groundwater flows into the
mine voids are important to estimate before mining commence since this will
determine at what rate groundwater needs to be pumped from the mining pits to
ensure dry and safe working conditions.
In order to obtain site specific data for the study area, several field investigations
have been conducted. These investigations include a geophysical survey, drilling
of monitoring boreholes and pump testing of the monitoring boreholes. These
investigations are done to obtain a better overview of the aquifer conditions in the
study area.
For the study area a numerical groundwater flow model was constructed and the
groundwater inflow was determined by making use of a water budget function.
The analytical approach to determining the inflow included four different methods.
A sensitivity analysis was done on the recharge with the numerical and analytical
methods.
The results from the numerical and analytical approaches were compared to
determine whether the analytical approach is in fact a good way of obtaining
values that relates with the numerically obtained results. If there is a good
correspondence between the analytical and numerical results, the analytical
approach can be regarded as a save and representative way to obtain
groundwater related values. Especially during the early stages of mine planning
analytical methods would be supportive to quickly determine mine related issues
as this will assist in decision making and related cost estimates. From the results obtained in this thesis it can be concluded that the analytical
approaches used during this study, although giving close to numerical answers,
cannot be used in an effective manner in determining groundwater inflows during
the early planning of mining.
The fact that the analytical approaches did not reveal representative values for the
groundwater inflows and also do not correlate with the numerical model results,
does not mean that this will be the case at another site with different
geohydrological characteristics. It is important to note that assumptions are
always made in analytical methods.
It is suggested that further research be conducted in relation with analytical and
numerical modelling of opencast mines. Research should be performed at several
mines to determine whether the relation between the numerical and analytical
approaches display similar trends than was found during this study. These mines
should preferably be on similar geological areas to compare with each other. The
only way to determine whether the analytical methods can in fact be used to get a
representative result is by repetition on several mining sites and also comparing
these values with the numerical model results and also the actual inflow rates from
the mine once mining has started.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-05272013-120359 |
| Date | 27 May 2013 |
| Creators | Boshoff, Elida |
| Contributors | Prof I Dennis, Prof GJ van Tonder |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-05272013-120359/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
Page generated in 0.0023 seconds