The City of Cape Town is concerned about the possible health risks of sewage overflows from the 9 000km-system, which is almost 50 years old.
Pumping stations, some of which are more than 20 years old, are experiencing system failures which also lead to overflows.
There are 3,2 million people in Cape Town and each one generates about 160 litres of waste each day, the city says.
It would take R5,6-billion to replace the sewer network and a further R500-million to replace the city's 382 pumping stations.
Mayor Helen Zille told delegates at this week's conference of the Institute of Municipal Finance Officers that the demand for the treatment of wastewater was increasing by 7 percent a year in rapidly growing parts of the city.
"We are investing R1-billion over the next three years to prevent public health and environmental disasters," she said.
This three-year rehabilitation of wastewater conveyance is to include replacement of old systems and creation of new bulk infrastructure.
In a report to the utility portfolio committee, Lungile Dhlamini, of utility services, said the complexity of the city's wastewater system meant there were many potential points for sewage to be discharged accidentally into the environment.
"The impact on human health will depend on the duration of exposure to an oveflow and the levels of pollutants in the overflow."
Sewer overflows and spills of untreated sewage contain disease-causing organisms, including bacteria, viruses and parasites.
Of the overflows between June 2006 and June this year, 17 percent arose from mechanical failure, 45 percent from electrical problems, 21 percent from blackouts, 7 percent from flooding and 7 percent from vandalism. Broken gravity and pressure mains accounted for the remaining 3 percent.
The reasons for the failures included "historical neglect" in planning and funding the long-term rehabilitation of the sewer system and poor replacements at the former seven municipalities.
Many of the sewer pipes are corroded, broken or poorly connected, which allows winter rainfall to leak into the system.
The city's sewers are intended to collect or convey only sewage or wastewater.
Dhlamini said the rehabilitation of the sewer network would require specialist and costly techniques. There are a limited number of contractors available for the specialised work.
Some of the sewers and pumps are too small to carry the volume of sewage from newly developed areas.
Many pipes are corroded and cracked. Pipes get blocked by grease or tree roots. Cable thefts also lead to system failures.
Dhlamini said the city would work with the transport, roads and stormwater unit to monitor the overflow of sewage into vleis, rivers and wetlands.
Most of the major sewage spills, on to beaches and into streams, have been in the South Peninsula, Tygerberg and Blouberg areas.
- Cape Times
Pumping stations, some of which are more than 20 years old, are experiencing system failures which also lead to overflows.
There are 3,2 million people in Cape Town and each one generates about 160 litres of waste each day, the city says.
It would take R5,6-billion to replace the sewer network and a further R500-million to replace the city's 382 pumping stations.
Mayor Helen Zille told delegates at this week's conference of the Institute of Municipal Finance Officers that the demand for the treatment of wastewater was increasing by 7 percent a year in rapidly growing parts of the city.
"We are investing R1-billion over the next three years to prevent public health and environmental disasters," she said.
This three-year rehabilitation of wastewater conveyance is to include replacement of old systems and creation of new bulk infrastructure.
In a report to the utility portfolio committee, Lungile Dhlamini, of utility services, said the complexity of the city's wastewater system meant there were many potential points for sewage to be discharged accidentally into the environment.
"The impact on human health will depend on the duration of exposure to an oveflow and the levels of pollutants in the overflow."
Sewer overflows and spills of untreated sewage contain disease-causing organisms, including bacteria, viruses and parasites.
Of the overflows between June 2006 and June this year, 17 percent arose from mechanical failure, 45 percent from electrical problems, 21 percent from blackouts, 7 percent from flooding and 7 percent from vandalism. Broken gravity and pressure mains accounted for the remaining 3 percent.
The reasons for the failures included "historical neglect" in planning and funding the long-term rehabilitation of the sewer system and poor replacements at the former seven municipalities.
Many of the sewer pipes are corroded, broken or poorly connected, which allows winter rainfall to leak into the system.
The city's sewers are intended to collect or convey only sewage or wastewater.
Dhlamini said the rehabilitation of the sewer network would require specialist and costly techniques. There are a limited number of contractors available for the specialised work.
Some of the sewers and pumps are too small to carry the volume of sewage from newly developed areas.
Many pipes are corroded and cracked. Pipes get blocked by grease or tree roots. Cable thefts also lead to system failures.
Dhlamini said the city would work with the transport, roads and stormwater unit to monitor the overflow of sewage into vleis, rivers and wetlands.
Most of the major sewage spills, on to beaches and into streams, have been in the South Peninsula, Tygerberg and Blouberg areas.
- Cape Times
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