The poor disposal of waste in parts of the Durban
Metropolitan Area (DMA) has had significant negative impacts
on many aspects of the natural environment as well as
negatively impacting on the health of some communities.
Soil and Freshwater Pollution
Soil and freshwater
the DMA are vulnerable to pollution from landfills, the
illegal dumping of waste and effluent from waste water treatment works.
Soil and groundwater can become polluted by landfill sites if
leachate (the liquid formed during decomposition of disposed
waste material) moves through the surrounding soil and
enters the groundwater. In particular, the leaching of heavy
metals and hazardous chemicals can be dangerous to plants,
animals and people. Recently designed landfills are engineered
with complex liner systems to collect the leachate which
is then stored in a leachate dam for further treatment and
ultimate disposal to sewer. Older landfills, and old
cells of existing landfills in the DMA have no or inadequate liners
in place, as this was not previously required by law.
of waste on land and into rivers throughout the DMA
contributes to soil and water pollution. It is also impacting
on biodiversity and
the recreational value of open space areas.
sewage works, which
service the DMA, discharge their final return flow
directly into the main channel of the nearest river.
Within the Durban Metropolitan Area, direct discharges
into the river channel occurs in the Tongaat, Umdloti,
Ohlanga, Umgeni, Umbilo, Umhlatuzana, Umlaas, Isipingo, Mbokodweni
and Little Amanzimtoti rivers. This has resulted in instances of
bacterial contamination and eutrophication of river systems. Eutrophication
is manifest as abundant growths of Eichhornia crassipes
(water hyacinth) in the Umdloti, Ohlanga, Umgeni, and Isipingo
rivers and of Pistia stratiotes (water lettuce) in
the Amanzimtoti and Little Amanzimtoti rivers.
The disposal of waste products to the air has resulted in air quality
problems in areas such as the Durban South Basin. Landfill sites have the
potential if poorly managed to contribute to air pollution when
hazardous substances such as benzene, trichloroethylene,
tetrachloroethylene, methane and naphthalene decompose.
The decomposition creates volatile gases, and if they
become concentrated in pockets, explosions can occur if a spark
is introduced. At the Bisasar Road and Bulbul Drive
Landfill Sites this problem has been mitigated through landfill gas recovery.
Investigations are being undertaken to use this gas an a
source of energy.
Seventeen point sources
(marine pipelines and waste water works) discharge effluent
into the sea in the Durban Metropolitan Area. Some of these
are run by private companies such as SA Tioxide and AECI who
manage deepwater pipelines. Sappi Saiccor located just south
of the DMA also has a marine pipeline discharge. Two of the
larger wastewater treatment works in Durban (Central Sewage
Works and Southern Sewage Works) carry out marine disposal of
waste via deepwater pipelines. The disposal of liquid waste to
sea has, in some cases, resulted in the discolouration of
water and localised pollution of marine areas. In general,
though, Durban's fast moving marine current disperses waste
material quickly resulting in minimal pollution.
Urban litter results in marine pollution when discarded waste
is transported via the storm water drain system into
the coastal marine environment. The marine area most heavily
polluted by litter is the southern Metro region around the
Umlaas and Reunion canals. The Harbour is also severely impacted
on as stormwater drains from the Central Business District
discharge directly into the harbour, making it unsightly at
times and posing a potential health hazard.
Landfill gas causes an unpleasant
smell in poorly managed landfills. Depending on the local
topography and climatic conditions, odours may spread over a
wide area. This impacts on the quality of life of communities
as well as the market value of the surrounding land.
Complaints about bad smells are particularly common during the
wet summer season when the landfill sites are kept moist.
This together with high temperatures facilitates the
decomposition of waste and production of odours. Landfill
waste is usually covered with material such as soil and rubble
at the end of each day to reduce odour problems. At some
landfill sites e.g. Bisasar Road, deodorising chemicals are
released if the wind direction moves towards residential
Dust becomes a problem at landfill sites due
to the movement of heavy vehicles transporting and compacting
rubbish. When sites are cleared of vegetation prior to
engineering works, larger areas are left exposed and this
provides a source of dust in windy weather. This problem has
partially been overcome by the tarring and wetting of roads
and other exposed areas.
Communities located close to landfill
sites can be impacted by air pollution and landfill gas. If
not managed properly, volatile organic substances and
landfill gas can be found in residential areas adjacent to
landfill sites. These cause burning eyes, sore
throats, and headaches. In addition, local water
resources may be contaminated by leachate if not properly
managed. This can lead to illness if the water is used for
domestic consumption. Poorly managed landfill sites attract
pests such as flies and rats which can spread
to surrounding communities. The closure of the Umlazi IV
landfill site was due to public pressure, prompted by concern
regarding community health.