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Home News CSIR confirms sewage outfalls pose no significant risks

CSIR confirms sewage outfalls pose no significant risks

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A study by the Centre for Scientific and Industrial Research (CSIR) into the City’s sea marine outfalls has confirmed that they pose no significant risk to human health and do not measurably affect inshore water quality or the wider environment. 

The 24-month long study was commissioned by the City of Cape Town in response to concerns about the impact of the wastewater outfalls on the marine environment and human health. It has also been reviewed by external scientists.

The City appointed the Council for Scientific and Industrial Research (CSIR) in 2015 to undertake a detailed assessment. The study took place over a 24-month period starting in late 2015 and was completed in mid-2017.

The findings of the study have confirmed the City’s position that the outfalls are not outstripping the assimilative capacity of the ocean. It also found that there are no measurable risks to human health posed by the outfalls through either swimming at the beach or consumption of fish caught off our coastlines. In addition, near-shore pollution (when it occurs) is as a result of urban run-off. This is typical of all urban environments.

To ensure a comprehensive assessment the study was designed to assess and measure:

             the quality of the sea water near the outfalls

             the possible accumulation of substances in ocean floor sediment

             the possible accumulation of synthetic chemicals in animal tissue.

             the characteristics and toxicity of the effluent

The final full report, data and analysis has also been externally reviewed by Dr Robin Carter from Lawndale Technologies, who found it to be scientifically robust, and who supported the findings and conclusions by the CSIR.

The CSIR Report, the External Review and the proposed long-term monitoring programmer has been submitted to the Department of Environmental Affairs and Development Planning as part of a new license application for the outfalls. The City will now continue with the ongoing long-term programmer of monitoring the outfalls to ensure public confidence and transparency going forward.

In addition to the natural waste our bodies produce, effluent contains a variety of synthetic chemicals from sources such as cosmetics, household cleaning products, bath and shower water, dishwashing water and laundry water. However, based on the chemical characteristics of effluent, and various effluent dilution scenarios in the receiving environment, the analysis shows that most chemicals and compounds in the effluents are likely to be diluted to concentrations protective of marine fauna and flora shortly after discharge (i.e. within a small distance of points where the effluent is discharged).

Trends in the concentration of metals, polycyclic aromatic hydrocarbons, polychlorinated biphenyls and non-steroidal anti-inflammatory drugs in the tissue of black mussels and west coast rock lobsters collected at sites along the Atlantic Seaboard of the Cape Peninsula in 2016 also provided no evidence that mussels or rock lobsters collected inshore of the outfalls had accumulated these chemicals to excessive concentrations in their tissue.

‘Our society produces a lot of waste and it is unavoidable that this waste eventually finds its way back to the environment in one form or another. There are over 84 000 synthetic chemicals that have been made by humans and no wastewater treatment plant is able to remove all of these components from effluent. This study confirms, however, that at current levels this waste can be safely assimilated by the ocean,’ said the City’s Mayoral Committee Member for Informal Settlements, Water and Waste Services; and Energy, Councilor Xanthea Limberg.

In addition to testing for the accumulation of synthetic chemicals, the study also looked at whether bacteria from the outfalls was reaching the bathing areas, finding that this was nothing for bathers to worry about. Bacteria dissipated within 300 meters of the diffusers (the outfalls are 1,7km off-shore), which is echoed by the results of our coastal waters monitoring programme, and the continued status of Camps Bay and Clifton as Blue Flag beaches.

‘Given the often negative and sensationalist coverage around these outfalls we are happy to have conclusive proof that disposing of waste in this way is not posing significant risks to bathers or the marine environment.

‘Going forward, the City has developed an extensive monitoring program with the assistance of four external expert marine scientists. This monitoring programme was submitted to the Department of Environmental Affairs and will be implemented as part of our permit to operate the outfalls,’ said Councillor Limberg.

The full CSIR Report, the Lwandle Review as well as the long-term monitoring programme as developed by four top external scientists is available here http://resource.capetown.gov.za/cityassets/Media%20Centre%20Assets/CT-Outfalls-Report.zip

Issued by: Media Office, City of Cape Town

Media enquiries: Councillor Xanthea Limberg, Mayoral Committee Member for Informal Settlements, Water and Waste Services; and Energy, City of Cape Town, Tel: 021 400 1299 or Cell: 073 271 2054, Email: Xanthea.limberg@capetown.gov.za (please always copy media.account@capetown.gov.za)

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