The Civil Engineering Contractor May 2018 | Page 27

“When considering treated effluent
for mixing concrete, it is important to
have the water tested in terms of the
national standard SANS 51008:2006,
and the engineer on the project would
have to give permission,” she says.
A common temptation for contractors is
to use water from rivers, dams, or canals
— but Adams highlighted that there are
both compliance and quality issues that
must first be addressed. Again, talking to
an expert is the best route for avoiding
risk and ensuring smooth project roll-
out. More recently, another factor has
become important: public visibility. She
notes that residents in places like Cape
Town are much more vigilant today about
non-compliant extraction of water from
public sources; this activity, therefore,
holds considerable reputational risk if a
user is found to be in contravention of
any water use regulation.
While seemingly mundane, there are
various other ways that water can be saved
on construction sites — including the
use of hand sanitiser for hand washing,
the installation of chemical toilets, and
the capturing of rainwater using drains
and storage tanks. “Greater awareness of
water conservation — to prevent wastage
through unattended hosepipes, for instance
— also goes a long way,” says Adams. nn
About the author
Xanthe Adams is a professional
engineer at SRK Cape Town. She holds
a master’s degree in Environmental
Engineering (water treatment)
and has been practicing as an
environmental engineer for the past
15 years, with a strong focus on water.
She has experience in water quality,
mine water management, stormwater
design, surface water hydrology,
floodplain modelling, and water
treatment. She also has experience
with construction contracts, as she
oversees the technical aspects of
construction monitoring and contract
management for numerous mine
closure projects.
Overseas, fibreglass tanks
are used regularly for
stormwater management
applications.
quality, it can have quality problems.
Common issues include high levels of
iron, manganese or even salt, so testing
would need to be conducted to establish
if further treatment is necessary and
practical under the circumstances.
Testing the yield of the borehole is
also important to ensure that the water
source can sustainably provide the
required water volumes.
“Most water use options will require
some form of permit or licence, so
professional advice at an early stage is
vital when considering the borehole
option for site water,” says Adams.
“Depending on the nature of these
applications, the process could be
a long one — with impacts on the
project timeline. The borehole option
may also be attractive for large projects
in remote locations, where access to
municipal or other sources of treated
water is difficult or expensive.”
Another alternative is treated sewage
or effluent, but this has not always been
well received as it is still perceived
as poor-quality water; however, the
use of treated effluent can be a simple
and cost-effective strategy to reduce
reliance on increasingly costly and
scarce drinking water.
“This is a great option for contractors
in a city like Cape Town, where people
are more water conscious than ever
and the city council has made treated
effluent easy to access,” she says. “It
is already being used by the city in
applications such as irrigation, and its
[city council’s] quality standards for
retreated water are high, as much of
it needs to be discharged into rivers.
Quality problems can occur, of course,
especially if an individual treatment
plant is not running optimally, so
professional advice and testing is
recommended.”
Applying to use this water from a local
municipality’s treatment plant is usually
a quick and straightforward process, and
the water comes at an economical price.
Contractors will generally just need to
assume responsibility for the transport
arrangements and need to provide clear
signage to show that the water is not
for drinking. Common applications
for this quality of water include dust
suppression and compaction, but it can
also be used for mixing concrete.
TECHNOLOGY
How water savvy are you?
Take the five-minute challenge for the most water-savvy site.
Ever wondered how your on-site water management strategies
rate when compared to your peers in the sector? Now you can take
a test and find out!
Just go to the SRK-supported Water War website at http://
www.waterwars.co.za/construction-competition/ and
answer some simple questions about the way you use water on
your current project.
The Civil Engineering Contractor will track your responses and
publish the most interesting results, including the most water-wise
entry, in the next issue as well as online, so hurry and enter now!
CEC May 2018 - 25