The health of waterways is of top priority for the City. For this reason, City officials have been working tirelessly, including through the night, to minimise the environmental impact of sewer overflow into Zeekoevlei, part of the False Bay Nature Reserve, which has resulted in the pollution being contained.

The sewer overflow was the result of heavy rains leading to significant stormwater ingress, damaged manholes in the vicinity and infrastructure damage due to illegal dumping into the sewer system. The spill has now been contained with no further seepage into the vlei. This follows successful efforts to divert most of the seepage away from the vlei and into the nearby cut off drain and wastewater pond system.

The City has been conducting regular water tests to monitor the water quality. Due to the high E. coli count, the water quality in Zeekoevlei remains above levels deemed safe for intermediate recreational contact. Water quality monitoring continues.

Efforts to date include:

• Sandbags being placed around overflowing manholes in an attempt to mitigate and divert the flow from entering the Zeekoevlei.

• Identification and repair of damaged manholes which were a likely significant contributor to the sewer overflows. Going forward, these manholes will need to be redesigned and built higher above the ground. The chimneys of the damaged manholes are currently in the process of being reconstructed.

• Emergency repairs to the inlet works at the Cape WWTW due to the overwhelming of screw pumps which had been progressively damaged by illegal dumping and wear and tear of the mechanical infrastructure. Ordinarily, the wastewater pond system would compensate for sewer overflows related to screw pump failure, but in this instance heavy rains, stormwater ingress, and damaged manholes in the area impacted the effectiveness of fail-safe measures. Nine temporary pumps were used at the inlet to assist in diverting some of the sewage away from the vlei. Most of the sewage entered into the sub surface cut off drains with some of the sewage going into the wastewater pond system.

• A draft Rehabilitation and Repair plan for Zeekoevlei sets out immediate steps between now and April 2022 regarding roads and picnic area, terrestrial ecosystem, banks of the vlei, and the water body. A consultant will be appointed to further develop this plan. Some urgent superficial cleaning of the banks is already taking place.

The City is now taking immediate rehabilitation steps, including:

• clearing of sludge, sand, litter and debris from the access road, paved side road and picnic sites;

• reinstatement and repair of brick paving;

• repair of tarred access road where subsidence has occurred;

• removal of a one metre edge of sludge, vegetation and litter;

• removal of litter washed in due to sewage flow; and

• bank shaping and revegetation.

Attention to the water body is critical and an upgrade of the main Zeekoevlei weir will be looked at to assist in improving the water quality and removing sediment, which will mitigate the inflow and accumulation of sewage.

The City will continue to engage with stakeholders to find ways to address concerns holistically, and has further responded to the pre-directive issued by the Western Cape Government’s Department of Environmental Affairs and Development Planning regarding the pollution at Zeekoevlei.

Major Infrastructure programme to improve resilience

The City is investing billions over the next decade to upgrade water and sanitation infrastructure. Upgrades will also consider how to make infrastructure more resilient against damage from illegal dumping and abuse of the sewer system.

Illegal dumping is also a major driver of damage to manholes, and the City continues to consider design innovations in response to this, while also replacing over 300 stolen and damaged manhole covers every single month.

The R350 million upgrade to the inlet works at the Cape Flats Wastewater Treatment Plant, for example, will consider the installation of mechanical screens to mitigate against infrastructure damage from material that is illegally dumped into the sewer system.

In the interim, residents are reminded that sewers should only be used to dispose of human waste, toilet paper and grey water. The City asks residents to please help spread awareness throughout their communities.

Rondevlei Rehabilitation Plan

Residents are advised that Rondevlei and Zeekoevlei are adjacent separate water bodies. Some recent sewage spills have impacted on Rondevlei, but surface-flow from Zeekoevlei will not flow into Rondevlei.

A previous sewer spill occurred on the southern end of Rondevlei between the 9-10 July due to a manhole on the Retreat/Seawinds line which was vandalised. Staff were unfortunately mugged and shot at while doing repairs, but were fortunately unharmed.

A trench was dug by the City’s Sewer Reticulation team to mitigate the impact on the nature reserve. This particular sewer spill did not enter Rondevlei itself. A mitigation/rehabilitation plan is being planned for the area. This will include scraping of areas in and around the affected areas in the nature reserve, and removing the scraped polluted material to a suitable disposal site. Ongoing water quality monitoring is taking place.

Source: City Of Cape Town