Tshwane's sewage-polluted land could take 100 years to fix

15 March 2021 - 07:18
By Paul Ash
Roodeplaat Dam, seen here clogged with invasive water hyacinth, has been further polluted by raw sewage flowing from Tshwane's broken water treatment infrastructure.
Image: Alaister Russell Roodeplaat Dam, seen here clogged with invasive water hyacinth, has been further polluted by raw sewage flowing from Tshwane's broken water treatment infrastructure.

Farmer Theuns Vogel, 68, was hoping that his vegetable farm on the banks of the Apies River would be his pension.

Instead, his wheat crops have failed, allegedly as a result of the raw sewage that has flowed unchecked from the Rooiwal wastewater treatment plant for the past few years.

“The collapse of the Rooiwal plant has totally destroyed the agricultural network in the area,” he said.

Vogel was speaking to TimesLIVE a week after the SA Human Rights Commission heard submissions from desperate Tshwane residents about the near-collapse of the city's wastewater treatment infrastructure.

“North of Pretoria, the Apies River is all raw sewage,” he said.

Vogel, who has been farming in the area since 2003, is one of six farmers whose water is supplied directly from the Rooiwal plant.

However, tests done by hydrologist Johan van der Waals have shown an E. coli count of 520,000 parts per 100ml.

According to the accepted standard, there should be no detectable E. coli in drinking water.

Untreated sludge flowing from the works has been spread onto nearby farms by heavy rains and leached into the groundwater.

Vogel and his neighbours now get their drinking water from five water tankers sent out by the city daily.

An estimated 40 tankers also supply the residents of Hammanskraal who have been unable to drink their tap water for almost a decade.

“It must be costing them billions,” said Vogel. “Why don’t they use that money to fix the plants?”

Dewatering excess sewage sludge is a critical part of the treatment process in which the water in the sludge is squeezed out in a belt press and filtered while the solid matter is fed into a hopper.

The collapse of the Rooiwal plant has totally destroyed the agricultural network in the area.

Vogel claims that only three of the plant’s 10 belt presses are currently working and the raw sludge has merely been dumped into the river.

Normally the sludge would be spread out in an open area — known as “sacrificial land” — where it is dried and turned into manure.

The sacrificial land at Rooiwal, however, spanned 50ha over the headwaters of a catchment area.

“So the guy downstream is receiving all of this,” said Van der Waals.

“The land can’t handle any more,” he added, “it’s saturated.”

The land could be rehabilitated in 5-10 years if the city embarked on an intensive programme, he said.

But leaving the land to recover on its own — even if the city stopped pumping raw sewage into the rivers — would take 100 years.

The city’s water pollution is also being felt at Roodeplaat Dam where a combination of raw sewage flowing into the dam from the Pienaars River and spreading invasive water hyacinths have all but made the dam unusable as either a water supply or for recreation.

Kobus Fell, who owns a resort at the dam, said the water hyacinth was spreading out of control with as much as 45% of the dam’s surface now covered by the invasive plant.

“On the 460ha dam that means more than 200ha is covered,” he said. “It’s horrific.”

Fell estimated that as much as 50,000 tonnes of plants would soon be rotting at the bottom of the dam.

“With all those decaying plants, the water is being degraded.”

Water and sanitation department officials visited Fell at Roodeplaat last week where he presented a plan to clean up the dam using a combination of manual removal and aerial spraying of herbicides where workers could not reach the plants.

If the programme was maintained through the winter there would be few plants remaining to reproduce and cover the dam, he said in the presentation.

Department of water & sanitation spokesperson Sputnik Ratau said the department was swamped with proposals but people did not want to follow the required processes.

“If we don’t follow process, we will fall foul of the water act,” he said.

Any interventions, such as manual plant removal and herbicide spraying that Fell had proposed, needed to be first proven to be effective solutions, he added.

“These are all the things that impact on it.”

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