Waste water ‘threat’ to Cape Town’s beaches
PHOTOGRAPHS showing patches of waste water in Table Bay and Hout Bay have stirred controversy. But the City of Cape Town is adamant that sewage is discharged responsibly into the Peninsula’s coastal waters.
“The bulk of the public can’t believe this. They think I’m crazy, they think I’m joking,” said Jean Tresfon, a marine conservation photographer who captured the images from his gyrocopter.
Concerns were heightened earlier this month when an application for a coastal waters discharge permit was posted on the city’s website, prompting questions about whether the city was discharging waste water illegally.
There are five deep-sea marine waste water outfalls along the city’s coastline.
The Green Point (1.6km offshore), Camps Bay (1.4km) and Hout Bay (2.1km) outfalls are managed by the city, while the industrial outfall off Milnerton is owned by the Chevron oil refinery, and the outfall off Robben Island (465m) by the Public Works Department.
Collectively, the City of Cape Town marine outfalls can discharge up to 55 million litres of waste water a day.
The city says on its website that while people may “feel uncomfortable about discharging largely untreated wastewater into the sea, it is important to consider that marine outfalls are carefully designed to safely disperse waste water deep under water, far from the shore”.
It adds that they’re also located in areas where ocean currents help disperse and carry the effluent away from the coast.
Tresfon countered, however, that the picture of the Green Point plume was taken 1.7km offshore, and stretched about “2km across”.
“All the outfalls are in bays… call it sewage, waste water, effluent or whatever euphemism you want to use, it’s not drifting away from shore,” he argued.
Megan Laird, a marine consultant at Anchor Environmental Consultants who specialises in effluent modelling and toxicity testing, adding that it was inadvisable to ever place marine outfalls in bays, as they retained waste water.
“Sensitive environments are retentive zones, like beaches, surf zones, bays and buffers around marine protected areas. We encourage that outfalls shouldn’t be situated in these areas at all… If an outfall is situated there, then waste water pumped into the sea never really makes it out. It gets retained in those environments.”
Tresfon said the day he captured the image of the Green Point plume, the conditions were calm, with no wind.
“Any other day, when the wind turns west or north-west, which is our prevailing winter wind, it will blow the plume to shore.
“The Green Point outlet is also situated in a wind shadow from the prevailing summer south-easter.”
Part of modelling outfalls includes investigating what effluent would do in different wind conditions.
Laird said: “If I model an outfall with an onshore wind, the effluent is blown towards the beach. That would be the worst-case scenario.
“An offshore wind offers an opportunity for more dilution.”
Eddy Bisset, a kayaker at Three Anchor Bay, fell ill in April after practising emergency rescue techniques in the bay.
“Water went up my nose and two hours later I was experiencing diarrhoea, stomach cramps, headaches and a slight fever… That day the water was greeny-brown in colour, and there was an acidic smell,” he said, adding that he had reported the incident to the city and to the environmental affairs department.
Vera Massie, an environmental consultant at Anchor Environmental Consultants, believes the impact of stormwater is underestimated.
“Stormwater drains discharge organic and inorganic matter: human waste, garbage, all sorts of pollutants. Ideally, treatment plants should deal with stormwater before it enters the sea, which also provides a location where stormwater quality can be tested.”
But she said this would be “spatially and financially difficult to achieve”.
Professor Edda Weimann, a medical doctor and public health specialist at UCT, said Bisset’s symptoms were “typical signs of a wastewater acquired disease”.
She raised the alarm about elevated E. coli levels on Cape Town’s beaches in a study published in an international environmental journal in 2013.
She tested sea water collected at Clifton, a blue flag beach, during February to March 2013, and recorded E. coli levels that far exceeded the recommended guidelines.
“Since then the pollution has become even more noticeable,” Weimann believes, with the growing population contributing to the escalation.
“We are part of a life cycle, and sewage water affects us, our children, but also fish, seals, whales and other mammals.
We are polluting the environment that we are dependent on.”
She said testing methods were also no longer appropriate.
“It takes weeks for a result to get on the blue flag board, and by then the water quality has changed. You’re looking
at results from three weeks previously. We should be testing our beaches every day.”
The city’s application for a coastal waters discharge permit, posted on its website on June 1, along with a call for a public participation process , comes five years after additional marine outfall permitting legislation came into effect.
Massie said “there was a transfer of responsibility”.
“The Department of Water and Sanitation used to be responsible for controlling the disposal of waste water, but they didn’t have full jurisdiction over coastal discharges. They covered estuaries.”
In 2009, the Integrated Coastal Management Act of 2008 came into effect, giving the mandate to the Environmental Affairs Department, making them responsible for the permitting system of marine outfalls.
“In the transfer from the Department of Water and Sanitation to the Department of Environmental Affairs, the latter has had to pick up the pieces associated with the gap in legislation,” said Massie.
The Department of Environmental Affairs offered the assurance that in the five years that have lapsed, and while its permit application is under review, the city’s outfalls are still legally bound under their Water Use Licence issued by the Water and Sanitation Department, and by the Green Drop regulation programme, a Department of Water and Sanitation initiative ensuring that waste water treatment plants comply with discharge standards.
City media spokesman Simon Maytham blamed much of the resistance to the outfalls on lack of awareness.
For coastal cities in developing countries, he said, the “strategy of wastewater disposal through an effective outfall with preliminary treatment is an affordable, effective, and reliable solution that is simple to operate, and with minimal health and environmental impacts”.
The costs of preliminary treatment, he said, are about one-tenth those of secondary treatment.
“Given Cape Town’s economic context, with intense pressure from urban migration as well as an ever-stretched rates budget, these outfalls are the most feasible option.”
According to Maytham, the option is also exercised in New York, Barcelona, and parts of California.
He said the system makes use of what is known as a diffusion system at the end of the outfalls.
“This system rapidly dilutes the preliminary effluent to at least a 100:1 at the immediate exit point of the outfall.
“This corresponds to a 99 percent reduction in contaminant concentrations in the receiving water, which is far beyond the capabilities of even advanced conventional treatment processes.
“This dilution instantly results in a very substantial contaminant reduction.”
Bacteria, Maytham said, were further controlled by locating the outfall so that transport of waste water to beaches or other water contact areas is “virtually eliminated”.
“Diffuser mixing is therefore usually much more important than treatment in mitigating environmental impacts.”
On recycling of waste water, an oceans and coasts representative in the Department Environmental Affairs said that if Cape Town residents emphasise their desire to see this become a reality, it will become possible.
“If the public were more favourable toward recycling waste water for reuse, there would be less of an impact on the environment from it.
“The municipality would need the buy-in from society and industry, but it is a sensitive issue.”
In Israel, 80 percent of its sewage (400 billion litres a year) is reused as irrigation water for agriculture and public works.
Countries like Singapore, Australia and Namibia are already drinking recycled water. Abroad, experts are talking about harnessing the economic potential of wastewater.
“We need to get the water industry to be known for its innovation rather than its conservatism,” said Water Smart Software chief executive Robin Gilthorpe, at the Economic Power of Water conference in San Francisco this month. Harnessing energy from wastewater streams was introduced at the conference.
“If using this energy is possible,” said Vincent Tidwell, of Sandia National Laboratories, “there’s five to 10 times more chemical and thermal energy in waste water than what is required to treat it.”
According to a 2012 Cape Argus report, South Africa’s water demands are projected to outstrip its available supply somewhere between 2025 and 2030.
The public participation process runs until July 10.
Comment, input or recommendations can be submitted to the City of Cape Town via fax 0214239540, e-mail [email protected], or by post. See www.capetown.gov.za.