Abstract:
This study assessed the groundwater quality around two municipal solid waste landfill
sites, in the city of Bloemfontein, Free State Province, South Africa. The two landfill sites are located
in two contrasting geological terrains, with both lacking some basic facilities found in a welldesigned
landfill. A total of eight groundwater samples were collected from pollution monitoring
boreholes near the two landfill sites, with five samples representing the northern landfill site and
three samples representing the southern landfill site. The samples were collected in the autumn and
winter seasons to assess any possible seasonal variations. They were analysed for physicochemical
(pH, electrical conductivity (EC), total dissolve solids (TDS), chemical oxygen demand (COD) and
total organic carbon (TOC)) and microbiological parameters (Escherichia coli, total coliform). The
results of the analysis showed that the waters from both landfills were generally dominated by Ca,
Mg, SO4, and HCO3 ions. Some of the major anions and cations in the water samples were above
the South African National Standard (SANS241:2015) and World Health Organisation (WHO)
permissible limits for drinking water. Majority of the boreholes had total dissolved solids and
electrical conductivity values exceeding the SANS 241:2015 and WHO permissible limits. Piper
trilinear plots for the two landfill sites showed that Ca(Mg)HCO3 water type predominates, but
Ca(Mg)SO4 and Ca(Mg)Cl were also found. These water types were further confirmed with
expanded Durov diagrams, indicating that that the boreholes represented a water type that is
seldom found which is undergoing ion exchange, typical of sulphate contamination. From the SAR
diagrams, boreholes in the northern landfill site had a high salinity hazard with only one borehole
in the southern landfill site having a high salinity hazard. The geology was found to play a
significant role in the distribution of contaminants into the groundwater systems in the study area.
The study concluded that the northern landfill site had a poorer water quality in comparison to the
southern landfill site based on the analysed physicochemical parameters. However, the southern
landfill site showed significant microbial contamination, due to the elevated amount of E. coli and
total coliform concentrations. The high permeability of the weathered dolerites in the northern
landfill site might have enabled the percolation of contaminants into the groundwater resulting in
the poorer water quality.
