More than 5,000 tonnes of armoured rock deposited between Southsea Castle and the Pyramids centre every week as part of £138m sea defence scheme

Since March this year the Southsea Coastal Scheme team has landed 50,005 tonnes of specialist rock from Norway - just over a third of what will be needed overall - to protect the land between Southsea Castle and the Pyramids leisure centre.

A barge has been seen working late into the night to supply the materials, due to the tide times.

‘We have a weekly offload of our Norwegian rock which is scheduled around tide times in order to float the barge in and out of the drop zone to ensure the barge can safely ground in the correct location,’ a spokeswoman for the project said.

Beneath the rock armour in front of the promenade is a layer of geotextile.

The spokeswoman said: ‘It may look as simple as a giant size haberdashery; but we take special care to ensure the textile is placed securely and smoothly, with a 1.5m overlap with each strip.

‘Acting to stabilise the rocks and prevent sediments rising and creating an unstable base, it is one of the important features of the new revetment.

‘By Friday (May 13) we should be up to 160m of the 600m of rock armour to be installed around Southsea Castle.’

However, the work has caused disturbance to some living nearby.

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One resident told The News: ‘For the past two nights there has been the crashing and banging of large mechanical equipment moving huge rocks from I think 2am

‘We accept works need to be done, but from an environmental health aspect this work is being carried out at great nuisance to residents.’

The section between the castle and Pyramids is known as frontage four in the project but is the second area to be worked on.

Work is still ongoing at frontage one - around Long Curtain Moat - which is expected to finish this summer.

To find out more about the scheme, residents can visit the project’s visitor centre, opposite Clarence Pier, on Tuesdays between 10am and 2pm to watch a wave tank demonstration.