Collapsed main contaminates stormwater system

The sewage spill which washed into the Sandriver Canal on Saturday April 21 is being cleaned by the City of Cape Town.

Mayco member for informal settlements, water and waste services and energy, Xanthea Limberg, said a bulk sewer main in Overcome Heights informal settlement had collapsed 3m underground, and effluent had contaminated the stormwater system and reached Zandvlei.

“The repairs and maintenance of the pipelines is the responsibility of the water and sanitation department, “she said, adding: “The repair work and clearing of the blockage will be carried out by an appointed contractor. Treatment of the stormwater system using bio-enzymes was carried out where sewage spillages occurred.”

In addition, Zandvlei estuary mouth was opened on Sunday April 22, to allow sea water in and to avoid trapping sewage in the vlei with the expected rains.

A by-pass pumping system was put in place, preventing any further spillage into Zandvlei.

Ms Limberg said that an alert informing users of the spill was put out through the Zandvlei Nature Reserve’s Protected Area Advisory Committee (ZPAA).

Monitoring of the area by testing of water samples would continue.

A loud siren-like noise on Saturday night April 21 had residents of Marina da Gama peering over their back walls trying to fathom its source. Ms Limberg said the noise had come from the vacuum tanker trucks which were used to reduce the sewage levels at the pump stations, to minimise the effect of the spill.

The Zandvlei Protected Areas Advisory Committee (ZPAAC) website posted news of the sewer collapse and spill on their website, and updated this as the situation progressed. Initially people were warned to stay out of the water.

By Tuesday, the spillage from the sewer was almost completely eliminated.

ZPAAC representative, Bernelle Verster, said in that public notice that the contractor was sourcing at least one additional pump to act as a standby in case of a breakdown, and also to assist with keeping the sewer flowing at peak times.

Ms Verster said on the website report that the structures built over the collapsed sewer were being moved, and the appointed contractor was on site and busy with repairs.

“Also, we note with gratitude that the new litter nets managed by residents of Marina de Gama (Mike Ryder and volunteers) seem to have done a good job of preventing the bulk of the oil slick relating to the spill from entering into the main Marina waterbody,” she said.

Ms Verster added: “The ZPAAC is an advisory body, of which the City is an equal stakeholder, just like the residents and recreational water users. The ZPAAC does not have the mandate to respond to the public. It is composed of representatives that the general public can turn to if they have anything to contribute.”