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Contractors World UK & Ireland Vol 6 No 1

33

Replacing 26-Tonne

Trent Tidal

Gate

H

aving been in service for over

75 years, the tidal gate on the

River Idle at West Stockwith in

Nottinghamshire has been replaced as

part of a continual improvement pro-

gramme being carried out by the

Environment Agency (EA).

The project, which took just over 3

months to complete, was awarded to

ECS Engineering Services as part of its

framework agreement with the EA.

The West Stockwith sluice gate forms

part of the tidal River Trent flood de-

fence scheme and was originally installed in 1938.

It operates automatically at every high tide to pre-

vent the River Trent flowing into the lower River

Idle, which prevents local flooding, reduces the silt

build-up in the River Idle and stops salt water

contamination.

The sluice gate works in partnership with the

nearby pumping station located just upstream on

the River Idle; between them they can act as a large

lock to allow narrow boats to navigate up the

river.

ECS, as the appointed main contractor, was re-

sponsible for the complete refurbishment contract

including the gate removal, installation and

commissioning.

The company has completed several projects previ-

ously at this site.

The timing of the recent project was planned for a

time of year when flooding was least likely to occur so

that the brief period between the removal of the old

gate and the installation of the new gate would not pose

any flood risk to the local area.

One of the major logistical issues was getting a crane

on site that was large enough to lift the 26 tonne sluice

gate, especially with restricted local access.

The answer came from Walkers Crane Hire, a local

crane hire company, that managed to position a 120

tonne Grove GMK 4100L all-terrain crane on site and

then rig it with 76 tonnes of ballast to give the crane a

rated capacity of 220 tonnes. With the calculations done,

all that was needed was a calm day to allow the old gate

to be removed.

With all the electrical services removed, the top

platform of the sluice gate, which contains the lifting

winches and the control gear, was removed to allow

access to the sluice gate itself.

The lifting operation required almost perfect weather

conditions due to the weight of the sluice gate and its

tendency to act like a sail in the lightest wind.

The project included the replacement of the steel

ropes and the gate runners which guide the sluice gate

into position during normal operation. It also involved

a specialist dive team to install two limpet cofferdams

which allowed the engineers to remove and replace the

gate running tracks under dry conditions.

Due to the size of the replacement sluice gate it was

transported to site in sections and then assembled ready

for the crane to return and complete the installation.

With only a minor adjustment, the new gate was craned

into position and secured before the top platform was

replaced and bolted in place.

With the main structure reassembled, the new wire

ropes and all of the electrical services were reconnected,

including the encoders which are used to control the

position of the sluice gate.

Having completed the rebuild, the engineers com-

missioned the sluice gate to ensure that all of the con-

trols and settings were working as required before re-

turning it to the Environment Agency.

[cw]

Contractors World UK & Ireland