The Civil Engineering Contractor February 2018 | Page 17

ON SITE
the dams. The V-drains vary in width from four to 24m
and they also catch some of the subsoil drainage, as some
water inevitably ends up below the slab, Keevy informs.
“Along the perimeter of the coal stockyard is a
fire water supply network, part of an extensive fire
suppression system that also has surface fire hydrants.
The water in the system is at a constant high pressure to
ensure immediate access when required,” he says.
Total laid piping (within Esor’s scope of work) snakes
an astounding 50km around the site. “This includes
concrete drainage piping, HDPE water systems, PVC and
UPVC sewage systems, and subsoil drainage from the
various buildings on site.”
HDPE welding specialists and suppliers on site, Sebetsa
Trading, ensured that the high-pressured piping was
expertly joined, completing the system to the highest
standards. “Diameters varied from 150mm to 640mm,”
Keevy says and adds that at the deepest point, the pipes
were buried at a depth of 35m.
Cable trench special lid preparations.
Challenges
When a project as intricate as this is undertaken,
challenges are inevitable. Within Esor’s scope of work,
the initial design on all the pressure piping systems was
going to be PVC, Keevy explains. “However, about six
months after we had started, that then changed to HDPE,
owing to the longer lifespan,” he says. While this change
happened before Keevy joined the project, he muses that
the change was initiated by the client, Eskom, through
the designers. “In the long run, this was the right
decision and will reduce maintenance and replacement
costs,” Keevy comments.
The arduous project management task fell on the
shoulders of the Kusile Execution Team (KET): a
collaborative effort between Eskom and Black & Veatch,
an American consultancy specialising in engineering,
procurement and construction (EPC) services for energy,
water, and telecommunications.
“Prior to handing over the completed piping system,
we have to flush and drain it and put a camera through
the section. It was then that we discovered sagging pipes
in some areas due to unstable surrounds,” he explains
and quickly assures: “The areas where we had challenges
have been reworked by recompacting and relaying, and
in some places, pressure grouting was undertaken to
stabilise the ground, around the very deep manholes for
example,” he says. “There were some cured in place pipe
(CIPP) repairs done by one of our subdivisions, Tuboseal,
a piping repair specialist, who realigned and/or relined
the relevant pipes.”
Storage dams
Keevy explains that water is reused on site extensively
and stresses that although this aspect was not part of
Esor’s scope of work, constructing two dams were: “We
were responsible for building two holding, recycling
dams. These dams catch the vast amounts of water that is
used for heating and cooling the turbines. This water is
Earthworks for coal stockyard V-drain.
The entire contract comprises the
installation of drainage systems and
high-pressure fire and water supply
piping in a range of diameters from
150mm to 630mm for pressure
lines, and up to 2 500mm for bulk
stormwater lines.
CEC February 2018 - 15