Kuils River Upgrade by Zutari for City of Cape Town, Western Cape

WINNER Kuils River Upgrade by Zutari for City of Cape Town, Western Cape

Development in the Stikland Industrial Precinct of the Western Cape was prevented by frequent flooding caused by the limited capacity of the Kuils River channel.

The 2 km long section of the Kuils River was in poor condition, with progressive and uncontrolled lateral and vertical erosion of the sandy bank and beds. Historical and more recent encroachment of existing developments into the floodplain and towards the river channel were problematic for the City of Cape Town in terms of managing this area. Periodic, aggressive clearing of invasive riverine vegetation had contributed to destabilising the river channel, putting sections of the City’s water and sewerage infrastructure at risk.

Therefore, a sustainable and environmentally acceptable river corridor plan had to be created in collaboration with the City of Cape Town.

To prepare the plan, a multidisciplinary project team was commissioned to provide hydraulic engineering design consulting services. The team had to ensure a natural-looking river that promotes biodiversity and protects adjacent properties from flooding.

Zutari went through several iterations and options during the design phase for the river cross section. The design had to be able to convey the 100-year flood within the 50 m river corridor, keep the annual flood (1-year flood) within the low-flow channel, and ensure that the cycle track is located above certain recurrence interval floodlines – as required by the City of Cape Town’s Floodplain and River Corridor Management Policy.

The approved plan for the upgrading of the 2 km long section of the Kuils River Stikland/Bellville comprised: • a 50 m wide river corridor made up of terraced, trapezoidal grass floodplain to contain the 100-year flood • a 150 m long by 3.5 m high gabion retaining wall • a 50 m long gabion drop structure • a 2.4 ha seasonal and permanent wetland to compensate for the loss of wetland habitat in the development area. The Kuils River Upgrade is an excellent example of a project that embodies the vision of the City of Cape Town’s Liveable Waterways Programme and will assist Cape Town in transitioning towards a watersensitive city by 2040. It also exemplifies what can be done when the public and private sectors work together to achieve a solution that is ultimately beneficial to all parties.

PROJECT TEAM

Client: City of Cape Town Developers: Redefine Properties and VDMV Property Holdings River Engineer: Zutari River Contractor: Burger & Wallace Construction Landscape Contractor: Cape Contours Landscaping Architect: Greenspiration Environmental Consultant: Gibb Freshwater Ecologist: Blue Science