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www.worldpumps.com
WORLD PUMPS April 2009Applications 17
In December 2008, Northern Ireland
Water’s £100 million Belfast sewers
project reached another landmark stage
with the delivery of six 15 tonne storm
water pumps from Bedford Pumps Ltd, a
manufacturer of large, bespoke water and
wastewater pumps.
The pumps, which are among the largest in
Northern Ireland, are being installed 40 m
below ground level at Duncrue Street at
the base of the project’s terminal pumping
station (TPS).
The station itself lies at the end of the
10 km network of new storm tunnels
currently under construction below Belfast.
The pumps are crucial elements to the
whole project, and when operational, will
work to alleviate storm conditions and
reduce the risk of flooding in the city.
Each pump has the capacity to deliver
around 3,500 l/s, which means that when
all six pumps are installed, together, they
could empty an Olympic sized swimming
pool in less than two minutes. They are
driven by 950 kW, 3.3 kV immersible, flame-
proof motors.
In addition to the six large storm pumps, the
station also includes two smaller FFT pumps
which will be used to discharge the lower
flows to the treatment works. NI Water had
to take the following design consideration
into account when selecting the FFT pumps.
constant flow of 750 l/s over the static
head range of 10 m to 36 m while
remaining hydraulically stable and
operating efficiently.
pipework was greater than 1.8 m/sec to
maintain a self cleansing velocity.
strategic positioning the NRV.
withstanding severe abrasion due to the
high levels of grit present in the pumpage.
protection in the event of flooding.
Brian Henderson, project manager, NI Water
welcomed the arrival of the pumps in Belfast;
"The arrival of these six storm pumps marks
another significant landmark in the project.
We have undoubtedly benefited from the
expertise of the team at Bedford Pumps.”
Ltd, explains how the design specifica-
tion influenced the selection process: “The
arrangement used at this site is a depar-
ture from the norm for deep well pumping
stations in that traditionally the drive motor
is situated at ground floor level thereby
ensuring it is kept dry in the event of a
flood. The pump is then driven via flexible
drive shafting. To support the shafts inter-
mediate plumber type bearings are required
at approximately three metre intervals. These
bearings in turn require support beams and
access for lubrication all of which add to
the cost of the installation and present an
ongoing maintenance requirement.”
Frank adds; “The alternative is to install dry
well submersible pumps. Whilst this over-
comes the drive shaft problem the integ-
rity of the pumpset is dependant on the
performance of the primary mechanical seal
of the pump.
“The solution for NI Water’s Belfast sewers
project was to use a conventional mixed
flow volute pump fitted with a packed
gland. This shaft sealing method is tried
and tested but also economic to maintain.
To protect the motor in the event of a flood
Bedford Pumps manufactured an IP68 flame-
proof machine which was close coupled
to the pump. As a result the arrangement
minimised the overall cost of the installation
whilst ensuring optimum reliability.”
The TPS and tunnel system remain on
schedule to become operational in early
2010.
www.niwater.com
Water & wastewater
Stormwater project is
underground successPart of a massive sewers project in Northern Ireland requires the installation of dry well
submersible pumps below ground. As the integrity of these depends on the performance of the
primary mechanical seal, the solution uses a conventional mixed flow volute pump fitted with a
packed gland.
Pump delivered 40 m below ground Level. Each of the six
15 tonne stormwater Belfast sewers project pumps has
the capacity to deliver around 3,500 l/s.