PROJECT
27
Atterbury developed the new 42 500m 2 (GLA) building
at a cost of more than R1-billion and aptly named it
‘River Creek’ in view of the high water table, on behalf
of a 50/50 joint venture between property developer
and investor Atterbury and JSE-listed real estate
investment trust Attacq Limited.
The new Deloitte premises consists of a ground floor with
six storeys of offices and four basement parking levels,
including nearly 2 000 parking bays. The total consolidated
staff complement to be accommodated in the new building
is approximately 3 000, however the building will have the
space capacity for a maximum occupancy of approximately
4 900 people.
Although there is also a combination of rainwater harvesting
and borehole water, the heart of the plumbing systems at the
Deloitte building is water supplied from the municipal mains,
which is stored in the basement in a tank with sufficient
capacity for two days use, and then pumped into the
reticulation system. The rainwater harvesting system
makes use of an advanced filtration system which will
purify the harvested water to potable water quality that
will be fed into the buildings reticulation system.
WHBO’s contracts manager, Colin Campbell, explains
that the 15 000m 2 floor containing the major portion of
the plumbing – piping, heat pumps, storage tanks and
rainwater sumps – was an intermediate floor. “This was
extremely useful in the construction phase as it allowed
us to establish a base. The basement floors below have
minimal plumbing, and we were able to spread out up
and down from this floor. It also allows offices to be set
and up and equipment stored.”
As part of its LEED (Leadership in Energy and
Environmental Design – a US green-building rating
programme) star rating, all hot water and hot water return
pipes throughout the building have lagging to prevent heat
loss and reduce energy consumption, which is in any case
generated by large energy-conserving heat pumps.
The potable water storage is contained on the fourth
basement level. The bathroom water piping is from
Mepla/Geberit. “The piping system in the water storage
section is all HDPE provided by Valsir, and is pumped
through the building via PPR (Polypropylene Random
Copolymer) pipes with welded joints. The water from
the mains enters system and is boosted through the
pumping tanks from the top and is then pumped out by
a series of three Grundfos variable speed suction pumps
to make sure the pressure is the same throughout the
building from the bottom to the top,” says Patrick Dowie
from Wat-Sol Design Technology, design and quality
control manager. This is achieved by three pumps in a
sequence of: a main pump, a secondary pump which
kicks in during times of high demand, and a third
on standby. The sequencing of these pumps rotates
regularly to ensure they wear equally.
Dowie says Grundfos was selected “as they are one
of the best pumps on the market”. “They are energyefficient,
use hardly any kilowatts and for value-to-cost
have no comparison.” The system also has a bypass to
the municipal water supply should the pump set need
replacing or maintenance. The pumps are on back-up
generator power, so that the building will always have
water, albeit with uneven pressure throughout the building.
The system includes a sump to collect groundwater
seepage, whereafter it is pumped to the irrigation tank.
The entire site has a high water table, which means
that considerable provision has had to be made to
contain seepage – consisting of one major sump, three
smaller ones and a borehole, the latter being used not
to supply water but simply to maintain the water table at
a constant level, says Campbell, and the borehole water
ends up in the tank system. When the sump system is
full, there is an overflow system to a weir, and hence into
the municipal water discharge system.
This is in addition to the rainwater harvesting system.
Indigenous landscaping is supported by efficient
“The rainwater
harvesting
system makes
use of an
advanced
filtration
system which
will purify
the harvested
water to
potable water
quality that
will be fed into
the buildings
reticulation
system.”
August 2020 Volume 26 I Number 06
www.plumbingafrica.co.za