INVESTIGATION work is set to begin ahead of crucial repairs to a key part of the conurbation's coastal defencs.

BCP Council has contracted engineers to focus their attention on the long groyne at Hengistbury Head, which is in a very poor condition.

Several voids were discovered in the foundations below the waterline. The council said this presents a risk of localised collapse.

The long groyne, which was built between 1937 and 1939, has been closed off to the public since 2019.

A BCP Council spokesperson said: “From Monday, November 22, ground investigation works will begin at Hengistbury Head long groyne.

"This work will help inform the design of the planned upgrade and repair of this long groyne, which plays a critical role in helping control coastal erosion in Poole and Christchurch Bays.

"The work will involve machinery drilling a 20 metre borehole at four different points along the groyne.

"Although disruption to the public will be minimal, we would ask that the public please take notice of the onsite signage and be cautious that plant machinery will be moving around this area.

"The work is expected to last a few weeks, although the works are reliant on tides and the weather so it may take longer than anticipated.”

Over the years beach material has built up around the long groyne, and other groynes in the area, covering and extending the once rocky shoreline. The wide, sandy beach now protects the soft cliffs from erosion by the sea.

As well as being regularly submerged underwater, a detailed inspection of the long groyne using sonar and laser equipment showed the state of disrepair.

Using part of £33million in government funding, the repair and upgrade works are scheduled to take place in 2023 and will include raising the entire structure in height to help provide protection for the next 100 years from predicted sea-level rise.

Along with other shoreline structures, the long groyne helps to protect coastal communities across the conurbation. Its current condition, age and the site’s prevailing weather conditions means it is unlikely it will continue to perform effectively, the council said.

Without the long groyne, beach material would rapidly wash away and the cliffs could start to erode again within a year.