Page 7 - LandscapeSAIssue114

PROJECT

In the same way, the approach to the
planting and earthworks was also to seat
the building into the landscape using
a locally indigenous planting palette in
order to meet the sustainability goals.

With the roof garden being an artificial
growing environment, irrigation was
very important. The extensive lawns
which form an essential part of the site’s
recreational value are also water hungry
and a non-potable water source had to
be found to meet this ongoing irrigation
demand in a sustainable manner.

The concert lawns are located on a natural
drainage line with fairly high groundwater
View of the rammed earth construction method and seating integrated with gabion retaining walls and levels. This natural groundwater seepage
balustrades. is what had previously allowed the lawns
to retain their active growth throughout
the dry, summer months. The building
was positioned across this natural
seepage line and a subsoil drainage
system diverts the ground water around
the building to a constructed well point,
from where the water is automatically
pumped into irrigation water storage
tanks. All irrigation for the lawns, new
planting and roof garden uses this
water source and when the available
water exceeds the irrigation demand, it
overflows into a constructed drainage
channel that diverts rainwater and
overland flow away from the building into
an unlined, constructed pond located on
the natural drainage line. This results in
the re-instatement of the natural ground
water seepage, maintaining ground
water conditions for the existing trees
and vegetation established along this
drainage line.
The pond has evolved into a year-round
water feature, creating a habitat for a
Gentle steps and shaped terraces provide a natural transition from the landscape onto the roof garden and wider range of vegetation and fauna to
viewing decks be established close to the visitor centre.
Timber deck walkways make the pond
accessible to visitors and groups attending
environmental education sessions. The
placement of large sandstone boulders
provides opportunities for visitors to rest
or get even closer to the pond.

Existing site aspects
The following aspects of the existing site
were taken into account for the landscape
design:
Existing indigenous trees, planted by
Friends of the Helderberg Nature Reserve
over many years, were obstructing the
position of the new building. The Viridian
team applied for a permit to have them
(mostly Afrocarpus spp) removed and in
exchange, a similar number of Cunonia
capensis and Afrocarpus falcatus trees
were planted in other picnic/lawn areas.
The location of the building into the embankment required careful design of the drainage system in order
to preserve the building’s structural integrity and reinstate the natural drainage pattern and groundwater
flows downhill from the structure. This has resulted in a design that recycles groundwater captured in
subsoil drains into a well that automatically fills the irrigation storage tanks.

Landscape SA • Issue 114 2022 5