 Bournemouth
groyne repair works 2009/2010
A £1 million project to repair four of Bournemouth's groynes; two at
Southbourne (groyne No's 51 & 52) in
November, and
two between the Piers (groyne No's 18 & 19)
in December 2009.
Work was completed in February 2010, carried out by Ringwood-based Raymond Brown
Construction Ltd., on behalf of Bournemouth Borough Council.
Groyne No's 51 & 52, Southbourne
November 2009 - the
damaged timber sections at the seaward end of the 35-year old
groynes were replaced with Portland Stone rock armour.
The £800,000
cost of this project was 100% Grand Aid funded by Defra
(the Government Department for Environment, Food and Rural Affairs)
through the Environment Agency.
Groyne No's 18 & 19, Bournemouth
December 2009 -
the damaged pre-cast concrete sections at the seaward end of the
40-year old groynes were replaced with Portland Stone rock
armour.
The £250,000 cost of
this project was 100% Grand Aid funded by Defra
(the Government Department for Environment, Food and Rural Affairs)
through the Environment Agency.
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Raymond Brown Construction Ltd has
clinched another major contract in Dorset adding the £800,000
project at Poole Bay on behalf of Bournemouth Borough Council
to the company’s expanding portfolio of work in the area.
Work began by mobilising the main
compound at Solent Beach Car Park back on the 9th of November
2009 where two 45tonne and one 65tonne excavator, a D65 dozer,
35tonne crane and two 25tonne dump truck were delivered.
Once established and braving all
weather conditions the site team set about the task of
removing the two dilapidated groynes in the period running up
to Christmas. Each pile was jetted out using a high pressure
jetting lance which meant the majority of the timbers were
removed in large sections. The timbers were then loaded away
off site for recycling. During the same period over
6000tonnes of locally sourced Portland rock in 5-7tonne pieces
were delivered and stockpiled on the beach.
 Following
the well earned Christmas shutdown the team returned to site
to find very favourable weather conditions which enabled the
start of the rock placing on the 5th January 2010. One team
excavating down to the design formation level and maintaining
the protective bund that surrounded the works and another team
following behind placing rock. Working late into the night to
capitalise on the good weather window; extremely good progress
was made. The following days weather and sea was kind and
with everyone working hard for long periods, the site team
were able to continue to make excellent progress. By the
evening of Monday 11th, only one week after the first rock was
placed, one of the two groynes had been completed setting the
record for the fastest groyne constructed in Poole Bay
according to Bournemouth Borough Council.
R.Hayman – Site Manager
January 2010. |
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Why are groynes needed?
The whole of
Poole Bay from Sandbanks to Hengistbury Head is an eroding
coastline. In order to safeguard cliff-top property and
infrastructure, a long-term programme of engineering works must be
implemented.
The beach
replenishment projects undertaken in 2006 and 2007 delivered more
than 1.5 million cubic metres of beach material to Bournemouth's
coastline. The resulting wide beaches have been a success in
terms of their function as a coast protection structure and for the
enjoyment they provide to Bournemouth's residents and visitors.
Beach control structures are now required to ensure they remain
that way for as long as possible.
Groynes have
been used extensively in the UK and abroad to tackle coastal
erosion. They work by reducing the wind and wave-driven
movement of beach material along the coast, and by trapping and
holding sand
 within
the groyne bays.
Why rock groynes?
-
Rock groynes
are relatively simple to construct, are extremely durable and, due
to their semi-permeable nature, have the ability to dissipate the
erosive power of wave energy.
-
The main
construction material (Portland Stone) is locally sourced.
-
Over time
rock groynes become colonised by a range of sealife that would
otherwise be missing from our flat sandy beaches
What plans for further coast protection?
The beaches
will be monitored and the Council will continue to work with Defra
and the Environment Agency on any future beach replenishment and any
groyne repair/replacement projects that may be necessary. Such
work will be carried out as part of the local
Shoreline Management
Plan, which was reviewed 2009/2010.
Rock Groyne Ecology
/Seaweed%20groyne_small.JPG) Since
the construction of rock groynes elsewhere in Poole Bay various ecological
benefits have become apparent as they became colonised firstly by
lower plants such as algae and lichens.
Barnacles and seaweeds
established themselves after a few years, followed by the limpets,
anemones, crabs and other life forms that are able to adapt to the
ever-changing tidal conditions of rocky shorelines.
In this way, rock
groynes add to the diversity of beach life, and provide inspiration
for a new
generation of wildlife enthusiasts.
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Site
Manager's Report January 2010
/Seaweed%20groyne.JPG)