Jack-up barge set to arrive in sea off Hengistbury Head

BCP Council has warned that the barge is expected to be in the sea near Hengistbury Head for two to three weeks throughout August.

Following ground investigations last winter, council engineers and contractors are continuing to carry out several surveys and investigations to help prepare for the upgrade and repair of the entire Hengistbury Head long groyne structure.

Activity around the long groyne includes underwater surveys to map out the depth and land beneath the surface while borehole investigations will show the composition of the ground below the structure.

Boreholes up to 20 metres in depth need to be drilled from both land and sea using a rotary drilling rig and a sea-based jack-up barge.

• Read more: Hengistbury Head long groyne investigations for major repair

A jack-up barge similar to the one arriving off Hengistbury Head. Picture: BCP Council

Working 24 hours a day, the barge will take boreholes from five seabed locations immediately beside the long groyne.

Councillor Mark Anderson, portfolio holder for environment and place said: “The 83-year-old structure has been critical in stabilising and controlling coastal erosion in both Poole Bay and Christchurch Bay.

“Along with the beach and other shoreline structures, the long groyne helps protect local communities and infrastructure so it is vital we upgrade it so it can continue to perform effectively, particularly with the additional threat of sea level rise and an increasing number of storm events.

“Without the long groyne, beach material would rapidly wash away, and the cliffs could start to erode again. This would eventually lead to the sea breaching Christchurch Harbour at Double Dykes and Mudeford Sandbank and the impacts could extend to the Purbecks and New Forest.”

• Read more: Long Groyne at Hengistbury Head at risk of collapse

All data collected from the drilling will help refine the design for the new long groyne structure to ensure the continued stability of the coastline and protect against rising sea levels over the next 100 years.

The long groyne was closed to the public for safety reason following an inspection of the structure in 2019 when it was revealed it to be in a very poor condition.

Several voids were discovered in the foundations below the waterline, with an associated risk of collapse. The groyne is regularly submerged in water.