The Utility Wide Safety Committee (UWSC) comprising
officials from Energy Regulation Board (ERB), ZESCO Limited, University of
Zambia, and Copperbelt Energy Corporation (CEC) recently visited Kafue Gorge
Power station to check on the rehabilitation works being undertaken at the power
station following the mudslide of 2005.
The committee was constituted in
May 2005 and was tasked to look at major happenings in the Zambian Electricity
Sector, one of which was the Kafue Gorge mudslide of 2005.
During the inspection, the
committee established that the culverts were being replaced and works would soon
be concluded. Water from the main gallery was now being directed to the right
channel without disturbing the operations.
The committee further established
that the drainage system which had been blocked had been opened and the entrance
door to the power house replaced. The mudslide had severely threatened the
operations of the power station.
Geological experts at the
University of Zambia and Konkola Copper Mines were then contracted to assess the
mudslide and advise on remedial measures.
A ZESCO task team and external
experts identified remedial actions to be undertaken in the medium to long term
in order to reduce or eliminate the risk of a similar disaster in the future.
Some of these measures have already been embarked upon. The measures include
slope stabilization and re-design of the culverts and other civil works to
improve the drainage so as to cater for flood waters and debris.
On Saturday 24th December 2005,
Zambiaâââs principal power station mudslide following a heavy downpour. The
mudslide caused by torrential rains in the Namalundu area besieged the power
station leading to its shut down.
As a result of the mudslide, the
generator flow and the pumping station were flooded with water and mud. The
slurry pump could not pump as it was chocked by roots, and muddy water. At the
pothead yard, the wire fence on the hill side was damaged and the pothead
platform was filled with sediment deposits leaving the pothead drains blocked.
The power house entrance and
access tunnel road surface and shoulders were severely eroded and the cable
trenches were seriously undercut in several areas. The three drains at the
entrance, surge gallery, and access door were completely chocked, meanwhile, the
power house door was damaged and there was a lot of sediment deposited on the
road, blocking accessibility.
In the power house, the four
units that were in service tripped. Unit 1 and 2 tripped on differential
protection whilst unit 5 and 6 tripped on flood protection, leading to loss of
production. As a result five battery chargers were partially submerged in the
mud and the newly supplied 135MVA transformer that was temporarily stored in the
transformer repair bay was contaminated with sediments.
Generator 1 and 2 and associated
turbine equipment were contaminated with sediments and rendered in-operational,
but for unit 5 and 6, only turbine equipment at valve floor was contaminated,
however, this could still be put back into service with minimal amount of work.
All drains in the powerhouse
including transformer pits and drain pits were overwhelmed with sediment and the
lubrication system on unit 1 was contaminated, leading to loss of over two
thousand liters of oil. Meanwhile, tools and equipment that were left in various
work areas under rehabilitation, (i.e. Turbine floor, valve flow, transformer
hall etc) were damaged.
The power house lift (elevator)
was rendered in-operational due to flooding in the lift sump. This meant that
all forms of transportation had to be done by way of the 8 kilometer road route
to the surface. The findings showed that some control cards of the elevator were
damaged as a result of the flooding.
Fortunately, the station did not
record any incident of injury or accident both during the mudslide and the works
leading to the restoration of the plant. To restore the power station, the
station team was mobilized to the power house entrance to divert the water that
was rushing down the power house access tunnel. The station emergency ejectors
were started; however, their effectiveness was slow due to the closure of the
generator cylinder gates (station flood protection).
Over 200 workers were contracted
to commence physical removal of sediment, unblocking of access ways, de-slugging
and restoration of drains, general cleaning and other tasks. Immediate
mobilization of station technical staff to assess and carry out immediate works
to restore whatever generation was possible was part of the immediate remedial
Several submersible pumps were
also deployed in various areas to control flooding, as the drains were not
functional. To supplement ZESCOâââs own equipment at the power station and
expedite the physical removal of sediment, heavy equipment was hired and
mobilized from various organizations like the Zambia National Service, Dana
Services Ltd, and KCM.
The Kafue Gorge power station -
Zambiaâââs largest Power Station is Located on the Kafue River and has been in
operation since 1971. The power station has an installed capacity of 900MW with
6 generators of 150MW each.