Efforts to improve the water quality and environmental health of the Milnerton Lagoon are gaining momentum, the City said.
At a recent quarterly stakeholder engagement meeting held to discuss options to tackle pollution at the lagoon, City officials presented a series of updates on critical infrastructure projects, ongoing maintenance activities and future strategies, including potential dredging options.
However, environmentalists say the bigger issue at hand is the overflow options into the river.
“Any failure will result in an inevitable back to square one,” a social media post reads. “Litter traps are another slow-burn response. We also need to recognise that raw sewage entering our ocean is unsustainable. Jean Tresfon’s regular flights once again showed the extent of this. Red tide and inshore fish reproduction are real issues, which the City ignores.”
The City said while it was making progress in tackling the pollution it organised the public meeting to share key updates, which collectively helped contribute to improving the water quality of the Milnerton Lagoon.
One of the issues discussed was current maintenance operations at the Koeberg Pump Station (PS). These include weekly manual screen cleaning to remove debris, and daily checks to ensure the pumps are working efficiently, the City says.
“Constant maintenance of wet well levels ensures all pumps, including a Pioneer pump, are fully operational,” said Mayco Member for Water and Sanitation Zahid Badroodien. “Upgrades at Koeberg PS have included constructing manual screens, replacing defective valves and installing a new alarm system. A fifth mobile pump has also been deployed to enhance operations. The City also recently acquired four new pump impellers and pumps.”
Looking ahead, long-term interventions at Koeberg PS involve constructing a new pump station to deliver a pump rate of 1 630 litres per second along with a new emergency overflow storage pond designed to accommodate up to four hours of emergency storage of sewage.
“Two new parallel rising mains, measuring 900 mm, will replace the existing fibre cement rising mains,” Badroodien said.
Key issues
The maintenance at Ryan’s Pond was also discussed, where the City pointed out the pond is maintained to receive spills, effectively preventing contamination of the Diep River and Milnerton Lagoon.
The broader community of Milnerton demanded the City to investigate the sewage flow rates in Joe Slovo and Dunoon which, according to residents, contribute a large part to the pollution.
Badroodien said Water Demand Management investigations in Joe Slovo and Phoenix Park revealed discrepancies between water demand and sewage-flow rates.
“Interventions, including valve checks, repairs and zero-pressure tests, have led to stable water pressure in Joe Slovo. By reducing the water pressure, water leaks in the Joe Slovo area are also reduced, which in turn reduces the amount of contaminated storm water needing to be diverted to pump stations.”
Enquiring about the Montague Drive bulk sewer upgrade, Badroodien said it was currently 50% complete for Phase 1, with several components at various stages of progress. The new sand trap and screening facility is were 30% complete, while more than 4 km of micro-tunnelling was nearing completion. Phase 2 was in the design stage, with construction planned from August 2025 to December 2026.
“Solid materials entering the Potsdam Wastewater Treatment Works (WWTW) have impacted processes and overall efficiency at the plant,” Badroodien said. “More than 30 000 cubic meters of solids, grit, sand and other inorganic materials were removed from various Primary Settling Tanks (PSTs), requiring extensive equipment and process control. It takes about eight weeks to clean one PST, and repairs to internal components such as weir plates and bottom bearings are necessary to improve effluent parameters.” He added several future plans were in place to ensure the effluent quality improves.
Potsdam WWTW upgrades
Potsdam WWTW upgrades started in April 2023 and include both mechanical/electrical and civil project components, with construction well underway. The construction phase includes ultrafiltration works, dewatering and the rehabilitation of old sludge storage ponds, along with new dewatering, ultrafiltration building, raw sewage inlet works and a Membrane Bioreactor.
“The City has evaluated several different dredging options to address the sediment and organic matter build-up in the lower Milnerton Lagoon,” Badroodien said.
“Various methods were assessed based on effectiveness, cost, social and environmental impact of the dredging and minimising waste to landfill. Following this detailed review the City has decided to proceed with a dredging plan that will dredge a key channel and remove the organic materials from the sand via cyclone technology, which will result in clean sand being returned to the lagoon and 600 cubic metres of organics and sediment being disposed of.”
He said the project was expected to cost around R70 million and last 11 months, but will first require an environmental authorisation.
