MEDIA RELEASE FROM NO SHIP ACTION GROUP 16/03/2010
North Avoca’s shoreline could recede by more than five metres if the ex-HMAS Adelaide is scuttled on March 27.
At high tide the shoreline could run 5.3 metres higher up the beach, according to figures calculated by a coastal engineer and a highly regarded geomorphologist last week.
Interestingly, Mr Nielsen is quoted as the author of the report which was used as a source of data for the Review of Environmental Factors (REF). The REF was written by Worley Parsons at the State Government’s request.
Since the REF was published on February 5 Mr Nielsen has produced further figures which show that the placement of a ship in Bulbararing Bay will change the wave direction slightly, or refract it.
This wave refraction could result in a permanent 5.3 metre regression of the beach, back toward beachfront properties.
Mr Nielsen believes the base grid size used by Worley Parsons for the wave refraction modelling was too coarse because the grid lines only interact with the ship at a couple of points. He believes the wave refraction modelling should have been done with a much finer scale, or grid size, which would have projected the interaction between waves and ship and waves on many more points.
The Worley Parsons REF did not follow through in assessing wave refraction changes and the implication this will have on the shoreline alignment and subsequent erosion. Essentially, the Worley Parsons REF is a primary base study.
The site selection report completed in June 2008 recommends an indepth study of the closed environment of the bay. This was not done
Additionally, the REF did not take into account the localised factors of Avoca Lagoon opening, which discharges about 1,500,000 cubic metres of water and 30,000 cubic metres of fine sand and silt when opened, which is on average twice a year. The REF did not take into account the mega-rips which occur when large storm swells hit, which happens about twice a year. Moreover, the REF did not factor in that the ship will essentially be in a closed beach compartment, which creates the potential for pollutants to concentrate.
No Ship Action Group’s (NSAG) Quentin Riley is concerned about beachfront erosion.
“It’s extraordinary - how can Peter Garrett even think of signing off on the scuttling of this ship? Big storms last winter gouged within metres of beach front properties at North Avoca. Add five metres to the wave reach and we could see the loss of homes.”
“Based on expert advice, Local Council introduced new rules that state if you’re building a beachfront home, you have to place it further back on the block because of receding shorelines.”
“But now the State and Federal Governments are wantonly dumping a ship which could take five metres of shoreline! It’s inconceivable. Beachfront owners will be furious.”
“The Government wants to scuttle the ship just 1400m off North Avoca and 1700m off Avoca Beach following a decade of lobbying by the dive community. The site was chosen because it is 32 metres deep and has a layer of sand about five metres deep to enable the ship to embed.”
If it goes ahead, the scuttling will be the closest ever to an Australian shoreline.
Residents of Avoca Beach and North Avoca only realised the ship would be in their bay around Christmas time 2009. Previously, it was announced on many occasions as being “off Terrigal”.