In particular, the report lists 18 pipelines on the Witwatersrand that it places in category five, the highest possible risk category.
It also warns of a potential threat to other metallic infrastructure, including gas pipelines and railway tracks.
Together with their proximity to disused mine dumps and wetlands, risk factors include age. Fifteen pipelines are more than 50 years old – the recommended design life is 30 years – and one was laid in 1912.
Gauteng’s 12-million human consumers are not the only ones at risk. A well-placed source warned that one critical pipeline on the West Rand, which carries the highest risk rating of all, sustains the entire platinum industry.
“If that pipeline failed, within 24 hours the industry would be on its knees,” the source said.
Threat of acid mine drainage
The report also underscores the threat of acid mine drainage (AMD) pollution to “critical biodiversity areas” in Gauteng, including the Krugersdorp Game Reserve and the Cradle of Humankind, a world heritage site.
The report was compiled by 10 environmental scientists from Umvoto Africa, an earth sciences consultancy based in Cape Town. It was commissioned by Rand Water and submitted in November 2012.
Although it does not directly address the “cascading consequences of pressure-induced pipeline failure … like loss of water supply, home/business/infrastructure damage [and] habitat destruction”, it calls for them to be dealt with in further risk-assessment upgrades.
Rand Water spokesperson Justice Mohale agreed that AMD poses a potential risk to pipelines, but said: “Rand Water has a mitigation plan to protect its entire pipeline network.”
He said the solution involves “supplying a specific cluster of customers separately from our current bulk potable water infrastructure”.
Rand Water was reasonably confident that its capital expenditure programme “will enable [it] to continue supplying world-class clean water 24 hours a day”.
However, Mohale did not respond to amaBhungane requests for details of the mitigation plan and its cost. The source said he is not aware that any of the report’s recommendations have been implemented.
Report being buried?
Curiously, the report does not appear to have been shared with the water affairs department or the national treasury.
In response to questions, Rand Water claimed to have passed it on to these departments, but, when questioned, both denied having seen the report.
AmaBhungane was told that the utility had kept the report underwraps because it shows the exact location of vulnerabilities in the pipeline infrastructure.
“More importantly, the report shows to what extent this water infrastructure is beyond its design life. This is extremely sensitive in terms of investor confidence,” said the source.
In the report, the scientists warn of the threat posed by uncontrolled pollution from old mines in three areas of the Witwatersrand – the western basin (Mogale City), the central basin (Johannesburg) and the eastern basin (Ekurhuleni).
It calls for “immediate and decisive action in mitigation”.
It also calls for Mvoto’s risk assessment methodology to be applied to other infrastructure, as electricity power lines, gas pipelines, railway lines and municipal infrastructure all face a similar risk.
“Anecdotal evidence suggests it is happening. This is why burying the report is damaging, as it prevents other parties from sharing the knowledge,” the source said.
The report found that the western basin, whose pipeline network is 638km long, is the most urgent area because AMD has been decanting there for 10 years.
It also contains the longest lengths of pipeline exposed to the highest risk, particularly the segments running parallel to Main Reef Road.
The central basin west, including the Gold Reef City tourist mine, contains the next projected decant site and is thus second in strategic importance, the report found.
Other findings were:
• Two pipelines in the western basin, P01 and P02, are threatened by AMD-polluted groundwater from a tailings complex at the headwaters of Tweelopiespruit and Rietspruit.
These are, in turn, linked to environmental threats to the Krugersdorp reserve and the Cradle of Humankind.
• Seven other pipelines around the Zuurbekom pump station in Vanderbijlpark are threatened by an acid water plume from a tailings storage facility.
• In the central basin a pre-stressed concrete pipeline and older steel pipelines are at risk, posing environmental threats to an “irreplaceable” biodiversity area near the Klipriviersberg, 5km from Soweto. Also under threat are pipelines through the Crown Mines “super-dump complex” that deliver bulk water to the northern suburbs and the West Rand.
The Crown Mines tourist mine, the report said, is at risk of imminent flooding.
• In the eastern basin there are risks to the N04 and N06 pipelines from AMD “plumes” related to old mining areas in Daggafontein, near Springs, and tailing sites where the pipelines cross the nearby Blesbokspruit.
The project director, Chris Hartnady, referred all queries to Rand Water, saying that the scientists had signed a confidentiality clause.