NEWS
5
Emergency desalination plant online
WSP — one of the multidisciplinary engineering consultancies on the continent —
played a crucial role in the fast-tracked development of the City of Cape Town V&A
desalination plant, feeding 2.0 megalitres of freshwater into the city’s network per day.
“Given the state of emergency of the water crisis in the region, this
was a rapid execution, top-priority project for all parties involved,” says
Marthinus Retief, principal associate: Coastal, at WSP Maritime Africa.
Retief confirms that the project was awarded to QFS in January 2018.
WSP, as subconsultants, immediately started working on the designs,
drawings, and specifications for the plant’s ancillary components.
Practical completion of these components was reached within two
months and the plant is currently finalising overall commissioning.
“We provided concept to detailed designs, as well as construction drawings
and specifications for the desalination plant’s ancillary works. As this
project was fast-tracked, significant focus was placed on where we could
save time, but not compromise on quality of design or constructability. We
also designed the ancillary works in such a way that the system can be
upgraded by up to 50% in terms of production, if required,” adds Retief.
The three main components that make up the ancillary works include
the marine intake pipeline and seawater pumping system, the brine
discharge system, and the injection system to convey the freshwater to
the localised water infrastructure network. WSP provided the marine,
civil, and mechanical design of these components. The desalination
process itself is owned and operated by QFS, along with Osmoflo.
“The seawater abstraction system is located close to the entrance
to the V&A basins, but is designed for optimised water quality and
rapid construction. The desalination process separates the salts from
the seawater and produces brine, which is then discharged back
into the ocean, and the freshwater is fed into the City of Cape Town’s
infrastructure networks. Care was taken to discharge the brine in an
environmentally acceptable manner,” says Retief.
WSP also provided project management services, as well as site supervision
for quality assurance and quick decision-making on site during construction.
“There was always a member from our team on site, working closely with
QFS and Southern Oceaneering (the contractor) to ensure that everything
www.plumbingafrica.co.za
WSP, one of the multidisciplinary engineering consultancies
on the continent, played a crucial role in the fast-tracked
development of the City of Cape Town V&A desalination plant.
Located at the V&A Waterfront, this desalination plant forms part of a
series of emergency water supply projects that the City of Cape Town
Metropolitan Municipality is implementing to supplement critically low
water resource levels in the district. Quality Filtration Systems (QFS), along
with Osmoflo, was awarded the work as the main contractor to build, own,
and operate the plant, as well as to decommission the plant at the end
of the contract term. WSP tendered as subconsultants to QFS, where the
company provided design engineering and site supervision services.
was done according to the design and for quality control purposes. This also
enabled the project team, collectively, to collaborate better and ensure that
any queries from site could be addressed and decisions executed rapidly.”
RETHINKING THE NORM
WSP designed the brine discharge system to operate under gravity, rather
than a pumping system as envisaged within the tender document. By
changing the hydraulics, WSP was able to optimise this process, which
saved the client capital and operational costs on the project.
Together with Southern Oceaneering, WSP designed a geotextile bag
weighting system to provide stability for the marine intake pipeline. This
enabled the contractor to more easily install the pipeline onto the existing
revetment slope and down to the required depth on the seabed. The
bags were concrete filled after installation to provide the required stability
against wave action. Being an alternative solution to conventional precast
concrete weight collars, it saved time on construction, while also reducing
risk during pipeline installation. WSP worked closely with the contractor to
ensure that the solution was constructible and optimised.
“The professional work and value added by WSP on the City of Cape Town
V&A desalination plant played an integral role in timely and professional
delivery of the project under extreme pressure. The engineering and project
management skills showcased by WSP during the project planning and
implementation phases were impressive and made the project for QFS
so much easier to deliver according to specifications,” says Herman Smit,
managing director of QFS.
“To ensure the project deadline could be met, we leveraged on the world-
class expertise of our team of Coastal and Civil engineers to find solutions
that were workable from a design perspective and quick to implement from
a construction perspective. Working on a high-profile project with such a
tight turnaround time truly shows the strength of your project team, and the
importance of collaborating towards the same end goal,” concludes Retief. PA
July 2018 Volume 24 I Number 5