SMOKING OUT ILLEGAL STORMWATER AND SEWER CONNECTIONS

These overfalls typically occur in winter, when the increased rainfall puts added pressure on the City's sewer system due to stormwater ingress. Some individuals or companies illegally connect their stormwater to the sewer system. This can potentially overload the wastewater treatment works and dilute incoming sewage, which paradoxically makes its treatment difficult owing to lower concentrations of organic matter in the water.

The smoke-detection technology is used to trace pathways, making it easy to identify sections where water by-laws have been contravened. The process involves a machine known as a smoke blower, which is placed over a manhole leading into a sewer pipe. Once the machine is turned on and

Councillor Zahid Badroodien, MMC for Water and Sanitation, with the Water and Sanitation Directorate’s Water Pollution Control branch conducting smoke detection testing in Gordon’s Bay heats up, it pumps smoke through the pipeline. The smoke travels the path of least resistance and quickly shows up at sites that allow surface water inflow. Surveillance teams then note where the smoke leaks out and identify any broken manholes, illegal connections, or weaknesses in the sewer infrastructure like cracked mains and laterals.

Smoke detection also enables the City to identify gutter downpipes that direct rainwater into the sewer system, and detect connections where backwash incorrectly deposits straight into the stormwater system. Furthermore, it becomes easy to locate unkerbed sewer gullies, which are those without a barrier wall to stop stormwater from draining into the sewer system.

If violations are discovered, the owners of the property receive a notice detailing the City’s findings and providing instructions for required repairs.

So far, the City of Cape Town has exceeded targets by testing 272 km of sewer pipeline in the 2022/23 financial year. The team is now well on the way to reaching its target of testing 170 km in the current 2023/24 financial year.

Areas are selected based on reports of:

• increased inflow into the nearest wastewater treatment works

• increased sewer blockages

• problems related to stormwater ingress

• sewer surcharges.

More recently, testing has been concentrated in Gordon’s Bay. A total of 6 370 properties have undergone a combination of smoke testing and door-to-door inspections. In the coming months, work will continue in Strand. The aim is to complete testing of 74 km of pipeline that passes through approximately 5 000 households.