3. Study area

In the Upper reaches of the Limpopo Basin's land use (see Figure 8 [10]), polluted mine water decants from underground and flows from the Randfontein mining environment into Tweelopiespruit stream and the surrounding farming lands [17, 37, 39]. The massive discharge has altered the nature of this water course. Bologo et al. [21] estimated that about 50 ML is decanted into the Randfontein receiving environment each day. Some effluent enters the Tweelopiespruit wetland on the mine grounds via surface seepage [39].

Previous studies as reported by [25] identified the quality of water in the receiving karst groundwater environment as comprising a mixture of acid mine drainage and treated wastewater. This has compromised the sustainability of biodiversity (both plants and animals) in the KGR. This degeneration process currently (2013) poses a threat to the Cradle of Humankind, which has a geological formation of dolomitic rocks that are susceptible to attack and dissolution by AMD.

Figure 8. Tweelopiespruit land use (Software platform: ESRI [10]. Source of shapefiles: Internet).

treated effluent, especially as the Tweelopiespruit supports wildlife in the Krugersdorp Game

• What are the trends in water quality of Tweelopiespruit and selected sampling sites around

• What is the overall downstream water quality impact of the treatment plant intervention? The overall aim of the research was to assess the impacts of treated AMD effluent on

• To evaluate the quality of water in the study area by analyzing and trending for SO4

, Fe, pH, and electrical conductivity (EC).

• To assess the impact of intervention (treatment plants) on Tweelopiespruit's health using

The results from this study were to be submitted to the Team which was carrying out the overall neutralization process at the Randfontein AMD treatment plant. The report could assist them in assessing the impacts of the treated effluent on receiving waters, judging from the

In the Upper reaches of the Limpopo Basin's land use (see Figure 8 [10]), polluted mine water decants from underground and flows from the Randfontein mining environment into Tweelopiespruit stream and the surrounding farming lands [17, 37, 39]. The massive discharge has altered the nature of this water course. Bologo et al. [21] estimated that about 50 ML is decanted into the Randfontein receiving environment each day. Some effluent enters the

Previous studies as reported by [25] identified the quality of water in the receiving karst groundwater environment as comprising a mixture of acid mine drainage and treated wastewater. This has compromised the sustainability of biodiversity (both plants and animals) in the KGR. This degeneration process currently (2013) poses a threat to the Cradle of Humankind, which has a geological formation of dolomitic rocks that are susceptible to attack and dissolu-

2− , Cl<sup>−</sup>

, Ca2+, Mg2+, Na+ and K<sup>+</sup>

, Fe, pH, and

2− , Cl<sup>−</sup> ,

Reserve (KGR).

346 Water Quality

2. Research problems and objectives

electrical conductivity (EC)?

, K<sup>+</sup>

Specific objectives were:

Ca2+, Mg2+, Na+

3. Study area

tion by AMD.

This research sought to answer the following questions:

Tweelopiespruit's receiving and downstream ecosystem.

• What are the characteristics of the different water sample sources?

the spatial and temporal trending patterns of the parameters.

resultant water quality samples from the specified study monitoring sites.

Tweelopiespruit wetland on the mine grounds via surface seepage [39].

Randfontein plant, using the parameters SO4

Tweelopiespruit, which carries the sampling sites for this study, is a defined stream network thus it is identifiable as a hydrological unit and the seven sampling sites are clearly marked in Figure 9. Except for F1S1 and F11S12, five of the monitoring sites are located inside the KGR.

During the period of the study, the stream received both treated effluent AMD from three treatment pilot plants located at the Randfontein experimental site, as well as AMD that was decanting from underground within the surrounding environs. At one of the pilot treatment plants, AMD tertiary treatment was being employed, where a fraction of its volume (about 50% of decant volume by three treatment plants), was collected and treated in a dedicated neutralization plant that used lime (Ca(OH)2) [35]. Two of the three pilot plants that treated AMD used this method while the third one employed a different treatment technology. The lime process was reported by Khorasanipour, Moore [41] as a preferred method to others like the alkaline method, claiming that it had a high removal efficiency for dissolved heavy metals, relatively low cost, and was insensitive to seasonal temperature fluctuations. In all the three treatment plants, AMD was pumped from underground shafts to the surface for treatment before the treated effluent was released to Tweelopiespruit. It was expected that by pumping and treating the AMD, the underground level of the mine waste water would fall below a critical level to allow stoppage of the decantation process.

For this research, the sampling points were chosen to represent the flow of effluent and treated water within the micro-catchment. This allowed for trending based on spatial locations of the sampling sites as well as temporal and spatial analysis of the data. Table 1 describes the sampling sites using the same identification which is used by the Department of Water and Sanitation (DWS).

Figure 9. Sampling points along Tweelopiespruit (Software platform: ESRI [10]. Source of shapefiles: Internet).


Table 1. Sampling sites on Tweelopiespruit.
