MORNINGTON Peninsula Shire had called on the state government to stop a $3 million rock wall being built at the Portsea front beach until a solution can be found to protect and restore the beach.
The shire says the government’s rock revetment “by itself will achieve erosion protection but will not guarantee the return of this iconic beach”.
The rock revetment treatment was chosen by Department of Environment, Land, Water and Planning (DELWP) after commissioning a study in 2016 by consultants Advisian.
The study produced seven options for the 600 metres of beach and foreshore which has receded by 25-30 metres.
However, the shire’s “strategy team” was dissatisfied with the study’s results, believing the rock revetment would “ameliorate erosion” but not restore the beach.
On the team’s recommendation, the shire hired its own consultants, Water Technology (WaterTech) to see if Advisian’s findings were “based on reasonably satisfactory investigations and information” and “determine whether the report methodology, information on which it was based, and assumptions made, provides reasonable certainty in achieving the objectives of ameliorating the erosion and remediating the Portsea front beach”.
Russell Smith, who heads the shire’s coastal, urban and heritage strategy team, said WaterTech criticised Advisian’s options paper for such things as failing to consider severe erosion of sand at Nepean Bay, Point Nepean and the build-up of sand at Shelley and Point King beaches.
WaterTech also claimed there had been a failure “to investigate possible causes of erosion such as [the Port Phillip] channel deepening” undertaken in the months before “the maximum shoreline change and in a period which was not a particularly stormy period”.
Other alleged shortcomings included the use of low resolution imagery and waterline estimates not taking account of variations in tide and “inter-seasonal effects”.
WaterTech said there “is insufficient information to allow for the selection of a preferred option for detailed design purposes” and that “further detailed analysis is required to assess any preferred options to minimise the risk they may have (and unintended consequences)”.
On Friday the shire issued a news release calling on the state government to:
- Commit to erosion control and beach remediation.
- Undertake protective works to the existing geotextile wall to enable further investigations on the coastal processes.
- Undertake further investigations that enable an informed assessment on options that will achieve erosion amelioration and beach remediation.
- Undertake community consultation on design options for Portsea Beach infrastructure.
The mayor Cr Bryan Payne said Portsea front beach, which is within his Nepean Ward, “is one of the state’s most iconic beaches” and “contributes significantly to the cultural heritage” of the peninsula and Victoria.
“Council looks forward to speaking with the state government to ensure this beach is reinstated and the foreshore protected from further erosion,” Cr Payne said.
Cr Hugh Fraser, also of Nepean Ward, said the government “must commit to our community that the government will undertake all the necessary steps to ensure a solution is found to both the coastal erosion at Portsea and Point Nepean National Park and Portsea beach remediation – otherwise Victoria will lose our iconic beach forever”.
DELWP is about to build a rock wall to prevent further erosion of a cliff at Mt Martha Beach North.