Articles & Case Studies


Posted: Friday 15th July 2011

In partnership with its South African licensee, concrete product supplier, Construction Supplies and Services, Hanson Formpave, a specialist paving manufacturer has supplied over 5,500m2 of its industry leading permeable paving system, AquaflowTM,for the construction of the parking areas of a new multi-million social housing development in Steenberg, a restructuring zone and suburb of Cape Town.

Developed out of a need for quality, affordable housing options for the rental market, namely low-income households and disadvantaged members of the community, the 450 unit housing development, undertaken by the Social Housing Company (SOHCO), is the first social rental housing project in the Western Cape.

Following the launch of the revised Management of Urban Stormwater Policy (May 2001) by the City of Cape Town, with particular focus on SUDS and situated on flat terrain, underlain by aeolian sands, this site was seen as the perfect opportunity to specify and install permeable paving.

Designed by consulting engineers, De Villiers Sheard, under the guidance of Hanson Formpave, Peter Wium, design engineer at De Villiers Sheard commented: “The success of projects such as this are integral to the future of housing and community within South Africa. We have witnessed far too much the exclusion of low-income families from the housing market, by working with SOHCO we are now able to offer social housing in good locations to low-income tenants.”

“By using materials like Aquaflow and adopting other eco-friendly building solutions like solar water heater systems, we can help guarantee that these housing schemes are sustainable solutions for the future of Cape Town,” concluded Peter.

The Technology

With its ability to deal with stormwater in a controlled manner, the Aquaflow permeable paving system was the ideal choice, helping to relieve the already overloaded stormwater infrastructure and outfall canal. The system is installed using an infiltration system so that the water is filtered and cleaned – to a pH neutral standard, before filtering downwards to the underground aquifer. There is, therefore, no impact on the existing infrastructure and watercourses. Receiving the full support of the City of Cape Town, Aquaflow’s performance is perfectly suited to the erratic and temperamental weather conditions of Cape Town.

Initial tests proved that the permeability of the site subsurface soils was approximately

3.5 x 10-5 m/s, allowing for full filtration into the sub-base and the receiving Cape Flats aquifer.

Predominantly laid in the parking areas of the development, over 5,500m2 of Aquaflow will deal with surface run-off as well as roof and verge flow. Tests also showed that there was penetration of sand into the 3mm grit between the pavers, to as much as 1cm, so, where necessary, sand traps were introduced at strategic locations around the housing development to trap wind blown sand – a notorious problem across the region.

Future Water Management

Plans have been set to inspect the paving at regular intervals, with both the government authorities and private sector working together to assess the success of the installation, ease of maintenance and above all, the system’s suitability as a Best Management Practice (BMP) option for the control and treatment of stormwater. A water table monitoring system has also been installed to monitor the aquifer below the social housing development, which, over time, can be used to review the performance of the permeable paving above.

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