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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