Waste generation is a widespread phenomenon around the world, of which the majority is
disposed by landfilling. In landfills, waste constitutes an integral part of the hydrological
system, and thus poses a threat to down-gradient groundwater and surface water
receptors. This research was undertaken with the purpose of determining the interactions
between landfill and the underlying Karoo aquifer, investigating the impacts of a
domestic waste landfill on the aquifer and further predicting the magnitude of future
contamination.
A domestic waste landfill site at Sasol Synfuels (Secunda), located on the Karoo aquifer,
was investigated in order to achieve these objectives. This site (Charlie I Landfill) has
been used by the refinery to dispose of all non-hazardous/general waste produced for the
past twenty years. It is not lined. There is no information available on the type and
volume of waste disposed, and the impact on groundwater was not quantified.
The landfill is classified as GMB+ (i.e. producing significant amounts of leachate), with
the bord-and-pillar mining method taking place underneath the site at the depths of 90-
120m. This implies a lower probability of subsidence at this position. Field
investigations indicate that there is a contaminant plume emanating from the landfill,
which is mostly concentrated in the upper part of the soil horizon. This horizon is mainly
composed of clayey loams and clay, averaging 3m in depth with a laboratory estimated
maximum hydraulic conductivity of 0.0128 m/day. It is underlain by the Karoo
sediments (sandstones and shales).
Regional groundwater levels have been disturbed by the presence of the landfill site, with
the higher water table closer to the site and the deeper water table moving away from the
site. According to the blow yields obtained, slug tests for boreholes and piezometers, as
well as the pumping tests, an average K- value of 10-2 was obtained for the aquifer,
except in regions where a dolerite sill or fractures exists. Soil and water quality analyses
indicate little contamination to groundwater; while contamination is mainly concentrated in the upper soil zone (i.e. originates from the surface leachate springs at the edge of the
landfill). Modelling of the contaminant plume also indicates a slow migration of the
plume to the adjacent areas.
The physical properties of soils indicate that retardation (by biochemical reactions,
sorption, cation-exchange etc.) of contaminants will occur with only very small quantities
reaching groundwater. The presence of leachate springs and low levels of contaminant
concentrations in groundwater indicates a limited vertical movement of contaminants.
Therefore, leachate produced by the landfill site does not infiltrate into the groundwater
system.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-05182009-120700 |
| Date | 18 May 2009 |
| Creators | Mndaweni, Sakhile Sibusiso Edwin |
| Contributors | Dr BH Usher, 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-05182009-120700/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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