OVERVIEW OF THE IMPACT OF MINING ON THE ... - IIED pubs

5.3.1.6 Human impacts on water resources (excluding mining)
The following activities can be expected to have an impact on water resources in the Little Olifants - Riet subcatchment:
• Landfills and solid waste disposal sites at all towns;
• Disposal of liquid (domestic, light and heavy industrial) effluent at all towns;
• Seepage from power station ash dumps;
• Disposal or seepage of high salinity power station cooling water;
• Moderate volumes of runoff from towns, as well as all other urbanized areas;
• Non-point domestic effluent from numerous small settlements and farms;
• Minor non-point impact from non-intensive commercial or subsistence agriculture;
• Non-point impact of agricultural return flows from intensive irrigation areas; and
• Litter and domestic garbage discarded alongside the many roads and highways that traverse the subcatchment.
Examples of the types of effluents that are discharged into this sub-catchment are shown in Table 5.4, which list
the water quality characteristics of four sewage treatment plant effluents.
Table 5.4: Representative water chemistry data for four major sewage treatment works in the Little Olifants –
Riet sub-catchment. (Data taken from Hodgson & Krantz, 1999).
Sewage Works Name
Parameter
Middelburg Naauwpoort Ferrobank Riverview
PH 7.7 7.9 7.8 7.9
Total Dissolved salts 385 562 618 628
Suspended Solids 1.0 6.4 13.2 11.6
Electrical Conductivity 76 93 96 99
C.O.D. 3.0 53 55 64
Na - 88 108 96
K - 15 13 22
SO4 250 182 249 192
Cl 62 45 54 79
Total Alkalinity 130 182 124 210
NH4-N 0.6 4.8 9.6 21
NO3+NO2-N 4.8 0.1 6.3 0.4
PO4-N 4.3 2.1 5.8 7.8
These treated sewage effluents will result in eutrophication of the receiving waters and will probably render the
water unfit for domestic consumption and irrigation on sensitive soils.
5.3.2 Mining and mineral processing operations
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