11/04/2006
- The Environment Agency is undertaking a £1.25
million refurbishment of the 240 year old Grand
Sluice in Boston from May to August this year.
The refurbishment is necessary to ensure the sluice
continues to work effectively. The Grand Sluice
prevents tidal waters moving up the River Witham
and so helps reduce the risk of tidal flooding
in the town.
The Grade II listed flood defence
was built in 1766 and is located at the tidal
limit of the River Witham. The structure consists
of three sluices, which have been owned and operated
by the Environment Agency since 1996 when the
Agency was formed, and a navigation lock, which
is owned and operated by British Waterways.
The majority of the construction
work will be at or below the level of the river
bed so once the works are completed there will
be little change to the overall appearance of
the sluice.
Navigation through the Grand
Sluice lock will not be affected by the construction
works, so vessels will be able to continue using
the lock as normal throughout the summer.
Proposed works will involve:
- Replacing the existing timber boarding in the
sluice bays with concrete
- Repairing the existing concrete downstream apron
- Placement of rock armour, below low tide level,
at the downstream end of the apron
The downstream apron is critical
to maintaining the effectiveness and stability
of the complete sluice structure. It protects
the river bed and sluice foundations from being
worn away by the force of water pouring out when
the sluice gates are opened. The apron is currently
in poor condition and must be repaired to maintain
the sluice.
A line of steel sheet piles
are also being installed below ground immediately
downstream of the sluice piers to form a new cut-off
wall. The wall will also help to improve the stability
of the sluice by preventing water seeping beneath
the structure.
Environment Agency Project Manager
Rob Barker said, "The Grand Sluice is an
integral part of flood defence of the Boston area
and it is essential to maintain the soundness
of the structure and its effectiveness.'
"We're going to be using
silent piling techniques to keep vibration and
noise to a minimum, but there will be some disruption
for the people of Boston who we hope can bear
with us while we get this essential work done."
