The Waterberg coalfields represent the last area in South Africa, which contain large
quantities of coal resources. According to Dreyer (pers. comm. 2009) the Waterberg
coalfields contain nearly 50% of the remaining coal resources of South Africa. Given the
great demand for coal both local and abroad, primarily to be used as a fuel source for the
power generation, the Waterberg coalfields have been targeted for large scale developments
in order to exploit the coal. The primary method for exploiting coal is through mining. Mining,
in any setting and any location has a diverse and often very serious impact on the
environment.
A scoping level study was under taken in order to determine the effect the mines will have on
the groundwater resources and the pre-mining conditions of the aquifers and the quality of
the groundwater. At present there is one operational colliery in the study area, the
Grootegeluk mine. This mine has been in operation since the 1980âs and has had a well
planned and operated monitoring system in place since the beginning of mining operations.
This mine was used as a model to determine the impact new mines will have on the area.
From the investigations it became apparent that the coalfield is situated in the Karoo
Supergroup geology with the Mokolian Supergroup being represented in the study area by
the Waterberg group quartzites. The coalfield is delineated by three major geological
structures, the Daarby-, Eezaamheid- and the Zoetfontein faults. With the Daarby- and
Eenzaamheid faults being impermeable according to Dreyer (pers. comm. 2009), The Daary
fault serves to divide the study area into an area west of the fault with shallow coal and an
area east of the fault with deeper coal. Only the shallow coal will be mined. According to
Dreyer (pers. comm. 2009), all of the planned infrastructure for the new mines will be located
on the Waterberg group rocks south of the Eenzaamheid fault or on the Karoo rocks east of
the Daarby fault.
To determine the impact the mines would have on the groundwater of the study area, aquifer
parameter testing (pumping test and slug tests), water quality determinations (inductively
coupled spectrometry), acid-base accounting and numerical modelling were conducted. The
results of the aquifer testing indicated low yielding aquifers with the harmonic mean of the
transmissivities indicating a low transmissivity of 0.4 m2/d. In addition the recharge for the
study area was calculated by means of the Cl and E.A.R.T.H. methods, resulting a value of
1.5% for the area. The average water level for the area was found to be approximately 28 m.
The water quality determinations for areas that had not been affected by mining, indicated
waters that had high EC values, near neautral pH value and medium to high Cl and sulphate values. The areas that have been affected by activities such as power generation and
mining, displayed higher EC, Cl, and sulphate values than the unaffected areas.
To more accurately determine the impact the mines would have on the area, numerical
modelling was done. Three scenarios were simulated using similar parameters to determine
the expected inflow into the mines and whether the mines would ever decant. The results
indicated that the worst possible scenario there was an influx varying between 755 m3/d and
1283 m3/d depending on the location of the pits. For the decant models, 50 years after mining
had stopped there was a rise of 3 m in the pits themselves. With the pits being simulated
being 110 m deep it is concluded that the mines in the area will never decant.
The results of the project indicate that the addition of new mines to the area will have an
effect on the groundwater quality and quantity and steps should be taken to minimise this as
much as possible.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-11182010-083011 |
| Date | 18 November 2010 |
| Creators | Bester, Michael |
| Contributors | Dr PD Vermeulen |
| 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-11182010-083011/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. |
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