An Engineer’s Report
Swimmer and engineer Gareth Floweday sheds some light on the recent spate of sewage spills across Cape Town’s gorgeous beaches. He says that he is encouraged by the relationship between civil society and the civil authorities…
There is much to do still in understanding and conserving the oceans we cherish. My tiny participation in the Beta Beach pump station improvement initiative was educational for me on many fronts and I have been tremendously encouraged by the passion, dedication and approachability of CoCT’s Coastal Management and the NSRI.
Over the 2022/2023 festive season the media informed the public about multiple sewerage pump stations around the Cape Peninsula experiencing overflows to beaches. Details were often not clear from the reports, but load-shedding and poor management of infrastructure development and maintenance were included in the commentaries, with numerous beaches being closed to the public for short periods to allow the pollution to disperse and assimilate.
One of my swimming mates, Dave Meinert, had become involved in a community initiative to engage the City of Cape Town (CoCT) regarding the recurring spills from Bakoven’s Beta beach sewerage pump station. I got chatting with him about it on 16 December and was particularly curious regarding why the problem kept recurring despite the focussed and collaborative attention it had received.
The more he told me, the more my engineering addiction was captured, “hook, line and sinker” by the collection of challenges and elusive solutions. Dave suffered my barrage of questions and promised to send me the initiative’s correspondence and assessment report. After reading the report collaboratively written by various CoCT departments and collated by the Head of Coastal Management. I was impressed by the serious intent and rigor of the assessment.
However, I did feel that something had been overlooked among the potential solutions considered. The primary cause of the spills related to the sump pumps not receiving power during loadshedding, the sumps filling up and overflowing into the sea. While a backup generator option had been assessed and deemed non-viable for various reasons, consideration of an industrial battery uninterrupted power supply (UPS) was not evident in the report.
Such a solution would be expensive, but I was curious whether there was a reason for not including its consideration in the report. I was also not convinced that the prioritised solution of telemetry hardware and a strategy of pre-loadshedding pumping would provide a robust solution since power failures will never be 100% predictable. If a UPS was technically feasible but challenging to CoCT budgets, perhaps the funds could be raised by the significant body of swimmers, divers and residents invested in obtaining a solution?
I therefore queried the UPS idea with the head of Coastal Management and the NSRI Station Commander, Luke van Riet, who was also actively involved and invested in the initiative. To his credit, the Head of Coastal Management responded promptly and very positively to the UPS suggestion. He promised to punt it to the CoCT engineering team and push for implementation via solution specification, quotes, procurement and installation. Luke was similarly agreeable to the proposal and promised to support and provide site progress feedback.
Within a week, the specifications had been generated and an approved vendor quote obtained. Within another week the UPS and “soft-start” variable speed drives (VSDs) for the pumps had been installed! The system has been monitored and has proven effective in powering the pumps and preventing load-shedding related spills since its installation.
On Sunday 22/01/2023, I joined the customary 9am Hot Chocolate community swim at Camps Bay. Having looked forward to the swim due to reports of warm, flat conditions, I was disappointed by what transpired to be the most polluted sea water I have ever been immersed in. It seemed that everyone who swam that morning was pretty disgusted and unhappy about the state of our precious bay.
Many (including me) assumed that it was related to the recently reported Beta beach pump station spill. I was disappointed to hear of the spill and certainly unhappy after experiencing such polluted water. I enquired with NSRI and Coastal Management about the recent spill and pollution levels and again received prompt and helpful information.
On 19/01/2023 the power to the Bakoven substation tripped out, robbing the pump station UPS of power for an extended period. The UPS system powered the pumps until the batteries depleted whereafter a spill occurred. Coastal Management was alerted, closed Beta Beach and monitored the E. coli levels before reopening the beach on 22/01/2023.
This event has triggered further CoCT planning for installation of cameras and sensors monitoring the Beta pump station to further improve the robustness of the solution against power eventualities other than simple load shedding.
The Beta pump station UPS system remains in successful operation and CoCT is currently assessing feasibility of UPS installations at other pump stations around the peninsula. Coastal Management and NSRI also provided helpful information regarding a distinction between the sewerage spill at Beta beach and the filthy water in Camps Bay. According to substantial research data including flow monitoring and water test data, sewerage spills at Beta Beach do not generally affect the water quality in Camps Bay due to the speed at which the spills dilute and assimilate in the sea.
The filth in Camps Bay on Sunday 22/01/2023 was proven by water testing to be non-human organic waste, mainly resultant from the decaying aftermath of the recent algal bloom. These algal blooms occur naturally due to the ocean upwelling of nutrients in the Atlantic and the decaying aftermath can linger in patches unless the prevailing south-east “Cape Doctor” winds push it out to sea. Additionally, marine organic waste such as partially digested krill and shrimp, and human rubbish normally further out at sea is blown into the Camps Bay bowl by longer periods of north-west (onshore) winds, such as those experienced the week prior to that Sunday.
While Dave teased me about hooking some local hero status for suggesting a UPS, I’m fully aware of more than a year of dedicated collaboration surrounding the pump station’s improvement and ongoing efforts mentioned. This for me is a ray of hope that penetrates the doom and gloom that has been so prevalent in our local and national society lately.
Urbanisation and societal challenges are real and complex, but perhaps with a bit of awareness and collaboration we can conserve our natural heritage and enjoy more glorious swims together!