ARTICLE
7
BLUE ROUTE mall – a green guide for responsible urban development South Africa’s largest sustainable urban drainage system (SUDS) and permeable paving project to date was completed in August at Blue Route Mall, a new shopping centre in Tokai, Cape Town. Spanning some 45 000m² of combined parking and drainage area, the development complies with the City’s Management of Urban Stormwater Impacts Policy which aims to reduce the negative impact of impermeable surfaces on aquatic eco systems. These measures are referred to in the Policy
but upsets the delicate balance of aquatic
as Best Management Practices (BMPs)
eco systems in natural water courses
and they fall into two groups, structural
such as rivers, streams and vleis, and
controls and non-structural controls.
unless remedial action is taken to reverse
The top layer of Inbitex® sheeting is laid at Blue Route Mall.
According to Martin Thompson, Cape
this process, the absorption, attenuation
Town’s head of Stormwater Catchment
and quality improvement associated with
Planning (South Peninsula), the primary
natural run-off are lost. Permeable paving
reason for the deterioration of urban water
is one of the structural controls we employ
is the disruption of the natural water cycle.
to maintain or mimic these natural flow
“Over the past decade Cape Town has
systems and prevent the wash-of f of
12- 18 month environmental analysis and
experienced unprecedented development
urban pollutants into receiving waters,”
Blue Route’s developers, Fountainhead
both in greenfield areas and in existing
says Thompson.
Trust, were not able to wait that long.
Some of the completed paved surfaces at Blue Route Mall which clearly show the voids between the pavers.
developed/ brownfield areas. Urban
Other structural controls such as green
In the end permeable paving proved the
surfaces, such as roads, pavements, parking
roofs, sand filters, swales, soak-aways
most cost-effective option, in achieving a
lots and roofing have been traditionally
and retention ponds could have been used
functional sustainable stormwater system.
impermeable and these surfaces increase
to treat water-borne pollutants and to
“One o f the gr e a t ad v an t age s o f
the volume of stormwater run-off and the
control egress into the city’s stormwater
permeable paving is that it uses the
accumulation of pollutants in rain water.
drainage system at Blue Route Mall.
same space as open parking areas, unlike
Impermeable surfaces also increase the
According to sustainable stormwater
swales and attenuation ponds which
systems consultant, Peter Wium, swales
require a dedicated single-purpose space.
“Increasing urbanisation not only places
were considered as an alternative solution
And besides controlling water flows into
pressure on existing stormwater drainage
but this option would have required a
stormwater drainage and rivers, in this
likelihood of flooding during heavy rainfall.
PRECAST VOLUME 7 • ISSUE 3 • 2013