Stockton Beach Taskforce looks to Hunter River for Stockton sand.
Looking south along Stockton Beach from Barrie Crescent showing sea wall and sand-bagging.
South arm of the Hunter River is bedded by marine sand that migrated into estuaries over thousands of years during changes in sea level. The sand is originally from eroded Hawksbury and Sydney sandstone that washed northwards, to become “marine sand” – a certain particle size and composition – during this movement.
Since construction of Newcastle Harbour entrance breakwater walls a century ago, sand movement from the south ceased to arrive at Stockton Beach, which has seen the shoreline steadily advance westward.
The crux of choosing the correct sand for replacing lost beachfront at Stockton is that using sand that is too fine (or coarse) would be counterproductive.It would wash away faster than the marine sand type that forms beaches.
Another major factor is to source matching sand. Regulations restrict what sand can be mined, and from where. Under the contaminated mud and silt that the David Brown dredge routinely removes from the harbour is a vast bed of marine sand that was used as Kooragang landfill when the coal loader was constructed. Permissions exist to use that sand for the aborted T4 coal loader.
Getting the sand from one side of Stockton to the other is a massive undertaking. The David Brown dredge is both unsuitable and has its own job of keeping the channel clear for shipping. Therefore a dedicated specialist dredge is needed. Pumping the sand from that dredge from offshore is almost as complex as a permanent piped solution across the peninsula.
Following a meeting of the Deputy Premier’s Stockton Beach Taskforce, City of Newcastle will meet with the Hunter and Central Coast Development Corporation, and Regional NSW to explore the possibility of using sand from the south arm of the Hunter River to replenish Stockton Beach.
Chair of the Stockton Community Liaison Group Barbara Whitcher supported the idea at the meeting earlier this week.
It’s encouraging to hear through the Taskforce the potential for relocating sand from the Hunter River to Stockton for short-term sand replenishment.
Lord Mayor Nuatali Nelmes said the Taskforce was making positive progress on achieving mass sand nourishment for Stockton Beach.
It’s encouraging that the Taskforce is making headway on finding suitable sand sources for mass nourishment at Stockton Beach and we’re optimistic about the potential Hunter River south arm opportunity.
Since June last year City of Newcastle has spent more than $3 million on emergency works associated with protecting coastal assets and property from erosion at Stockton Beach, including sandbagging and safety measures.
The decision to access the initial sand for a beach nourishment campaign was approved in the Stockton Coastal Management Program 2020.
Meanwhile, council has announced the use of ‘Kyowa Rock Bags’ in emergency works rather than sandbagging at the northern end of Stockton Beach.
This should negate the need for ongoing emergency response at Barrie Crescent and for the two buried terminal protection structures (Stone Street and Griffith Avenue) as approved in the Stockton Coastal Management Program 2020, saving $2.45 million and buying time for the Taskforce to achieve mass sand replacement.
Rock bags proposed for use at Stockton Beach erosion sites to replace sand bags. Image ~ Bluemont.
The rock bags are a patented flexible mesh product used for erosion protection which are more durable and sturdier than traditional sandbags. Their structure absorbs wave energy in similarfashion to a line of trees in a windbreak.
They will be assembled off site at the Ballast Ground in Stockton, before being installed at the Barrie Crescent section of beach.
The bags will provide up to 15 years protection which allows for a window of time in which mass offshore sand nourishment can be achieved, as outlined in the Stockton Coastal Management Program 2020.
City of Newcastle’s Acting CEO Ken Liddell said that in the meantime, the rock bags will be a significant improvement on the sandbags currently in place.
The innovative rock bag technology to be used at Stockton Beach will provide a range of benefits, not the least to provide further protection for the community and offsetting ongoing reactive emergency, and capital works costs.
Upgrading the emergency protection to rock bags will provide greater protection to coastal properties while allowing City of Newcastle to reinstate a passive recreational area at Barrie Crescent Reserve,” Mr Liddell said.
The rock bags will be placed in the same location as existing sandbags, along the Barrie Crescent frontage from the northern end of the Mitchel Street seawall at Stone Street to Griffiths Avenue road extension.
Coastal Management Programs (CMPs)
City of Newcastle has also confirmed it will complete three coastal management programs (CMP) in 2021, including an updated Stockton CMP, a Newcastle Southern Beaches CMP taking into account the area between the southern Harbour Breakwater to Glenrock, and an Hunter Estuary CMP completed in partnership with Port Stephens and Maitland councils.
The revised Stockton CMP will take into account the roughly three kilometre section of coastline north of Meredith Street not included in the Stockton CMP 2020, and include additional studies which were not possible to be completed prior to the NSW Government’s shortened 2020 deadline.
Community engagement on the CMPs is expected to start in early 2021.