A £1.9 million, five month project to create five new rock groynes between Branksome
Chine and Branksome Dene Chine.
Construction was completed May 2009.
Poole’s beaches following the replenishment project 2005/06 was wide enough to function
as a coast protection structure, and controls were required to ensure it remained
that way for as long as possible.
In 2008 planning permission was granted to Poole Council’s Coastal & Drainage team
for the construction of five new rock groynes at Branksome Chine and Branksome Dene
Chine, each measuring between 45m - 75m in length.
The contract was awarded to Dean & Dyball (now Balfour Beatty); construction work
commenced 24th November and was completed on 5th May 2009.
The choice of rock groynes for this project followed more than three years of detailed
investigations and analysis by HR Wallingford.
Engineers from Italy, Holland and New Zealand were involved in the first stage of
the study which considered more than 20 options for beach control structures. A final
report recommended four options for detailed consideration - three groyne options
and one submerged reef option. An economic appraisal concluded that rock groynes
were the preferred option.
This project at Poole is a move away from the traditional coastal protection scheme
in that a post project appraisal and programme of beach monitoring is being funded
by Defra as part of the overall scheme, and will compare outcomes with computer modelling
by HR Wallingford. The results will inform Environment Agency research, and help
the refinement of beach plan shape models in the future.
During this project large excavations were made at the back of the beach for construction
of ramps. There foundations were taken to below the level of sand before beach replenishment
Ramps allow access across the beach for, for instance, the beach rake and tractor.
They also provide access from the promenade to the beach and the groyne walkways,
and allow easier access for the less able and those using mobility scooter or wheelchairs,
buggies and prams. The size of the excavation is due to the working area required
to provide the long 1:20 slope that complies with Disability Discrimination Act (DDA)
During construction sand from the excavation was placed seaward to give protection
to the workforce and the working area. Once construction work was complete the sand
was replaced in the excavation trench. Current beach levels mean that the majority
of the ramps will be covered by sand but the extent of the ramps will ensure they
can be utilised if / when beach levels drop.
Five new rock groynes, of varying lengths, between the Chines at Branksome Beach
The groyne plan shows the position and relative size of each of the five groynes.
The plan is too large to display on this page, but a pdf version is available