Cape Town’s Zeekoevlei to be dredged over two-year period

The City’s Spatial Planning and Environment Directorate is pleased to announce that preparations are under way for the dredging of Zeekoevlei, an operation that will take about two years as part of our efforts in improving the water quality of the waterbody. Residents living in the vicinity of the False Bay Nature Reserve and recreational users will note a beehive of activity in coming weeks as the contractor is preparing the roads and dewatering ponds, and installing two pipelines. If all goes as planned, the physical dredging of two sections of Zeekoevlei will commence in May 2025.

Zeekoevlei is located in the False Bay Nature Reserve, a Ramsar site of international importance for wetlands. The City is also accredited as a Ramsar City. Improving water quality is a key international commitment which is aligned to the Mayoral Priority Programme (MPP): Sanitation and Inland Water Quality MPP.

Over the past decades, there has been a significant build-up of sediment and nutrient rich organics in the Zeekoevlei lakebed that has resulted in algal blooms, which has been impacting the overall health of the vlei and its water quality for recreational users.

‘Improving the water quality at Zeekoevlei is one of our top priorities, and I am pleased to announce that after many months of preparations we are now at the point where the contractor is on site, getting the necessary infrastructure in place to commence with the dredging of two sections of the waterbody by May this year. The dredging of Zeekoevlei will also assist in removing pollutants and improving the overall health of this ecosystem. The intention is to dredge and remove as much of the nutrient rich sediment as possible over a period of two years or so,’ said the City’s Deputy Mayor and Mayoral Committee Member for Spatial Planning and Environment, Alderman Eddie Andrews.

Two sections of Zeekoevlei will be dredged: first Storm Bay and thereafter the contractor will move to the section known as Home Bay. The dredged material will be pumped with a slurry pipeline from Zeekoevlei to dewatering ponds where the sediment can dry out.

‘The City has not undertaken a dredging project since 1983 when parts of Home Bay were dredged.  The current dredging is much more extensive and thus, is a significant milestone event. We will, for the first time ever, use a floating suction dredger to dredge organic rich sediment from the vlei bed. Normally, dredging is done by crane from the water’s edge, but given that the two sections to be dredged are located far from the edge, the City will be using a floating pontoon instead. We are excited about this project and will let the public know once the pontoon is on site,’ said Alderman Andrews.

Dredging is an extremely complicated process and requires significant preparatory work. Residents and visitors should expect a lot of activity in these areas where the contractor will be busy installing two pipelines, and improving the access roads to the Cape Flats Waste Water Treatment Works (WWTWs) area.

Dredging information

• Two sections of Zeekoevlei will be dredged over a period of 26 months, namely Home Bay and Storm Bay
• The total volume of sediment to be dredged from Home Bay is 157 000m³ and is estimated to take about 14 months
• The total volume of sediment to be dredged from Storm Bay is 207 000m³ and is estimated to take about 12 months
• Hydrographic surveys of the dredged area will be conducted every two weeks to measure the progress
• The dredged sediment will be pumped from Zeekoevlei via a 4,3km long slurry pipeline to ponds for dewatering and storage
• The slurry pipeline will cross several roads within the area, amongst which Governors Walk and Peninsula Road
• The supernatant water will be pumped from the dewatering ponds to the Cape Flats WWTWs via a 2,3km long pipeline
• The contractor will be constructing rubble mound bund walls at the dewatering ponds to assist with the dewatering and drying of the dredged sediment
• Dewatering sumps will be constructed around the perimeter of the dewatering ponds to assist with the drainage of supernatant water to the Cape Flats WWTWs
• The contractor also needs to upgrade the access roads within the Cape Flats WWTWs area for the transportation of dredged sediment

How the dredging will impact surrounding areas and visitors

• The work will happen from Monday to Saturday, however, work may be scheduled for public holidays and Sundays when absolutely necessary
• There may be noise during working hours, and the dredging process will release an odour as organic material and sediment are disturbed
• Recreational users will have access to Zeekoevlei for rowing and sailing, but certain sections will be closed in the interest of safety
• The public will have access to Zeekoevlei, including for bird watching, but certain sections of the False Bay Nature Reserve will be restricted while the work is happening

The City will let the public know once the actual dredging has commenced; it is anticipated to be commencing in May 2025 if all goes as planned.

Caption: All-in-all, it will take about 26 months or just over two years to dredge Home Bay and Storm Bay, two sections within Zeekoevlei at the False Bay Nature Reserve. The contractor will be installing two pipelines, including a slurry pipeline, and improve access roads within the area of the Cape Flats WWTWs in preparing for this project.

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