Stockton erosion: Mitchell Street seawall dropping and falling forward as beach undermined by surf

The Mitchell St rock wall, the suburb's last main line of defence, is dropping and falling forward and gabion baskets used to stabilise the structure and direct water flow are failing.

The wire cages filled with rocks were used as shore-stabilisation structures above and below the rock wall when it was built about 30 years ago.

But as the erosion worsens and larger waves regularly pound and overtop the wall at high tide, the gabion baskets are being exposed and rusting.

City of Newcastle said this week it planned to address the problem during works to fortify the wall.

The spokeswoman would not be drawn on a timeframe for the works or reveal any information about engineering assessments of the wall or subsidence data.

"The final details of the remediation strategy for the seawall are being confirmed and will include the management of all gabion baskets above and below the water level," she said.

"While gabion baskets at the top of the seawall are expected to be repaired, the primary strategy for maintenance will be the placement of an additional 6600 tonnes of suitable rock."

Long-time Mitchell St resident Al Metcalfe expressed concern as waves strip soil from the grassed area adjoining the rock wall and the top gabion baskets continue to give way.

"It's just getting worse and worse and worse as the wall drops and the waves come over it." he said.

"I think if those cages go, we're in a lot of trouble with this wall."

University of Newcastle School of Environmental and Life Sciences conjoint associate professor Ron Boyd said seawalls are "not forever structures".

Professor Boyd said the wall was in need of major maintenance and to complete the works City of Newcastle had to apply for funding to the NSW government.

"With no sand in front of it currents and waves are attacking the base of it all the time," he said. "It's being undermined and sinking."

Residents estimate the wall, that protects a main gas line that runs down Mitchell St, has dropped up to 1.5 metres due to the worsening erosion.

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