The Princetown community are concerned that Corangamite Shire Council are basing their decisions on inadequate information. The Princetown Wetlands & Estuary Preservation Group (PWEP) commissioned an independent floodplain expert, Matthew Hayes, to conduct a review of GHDs Hydraulic Reports and to look into floodplain management issues around the proposed Montarosa resort development on the Gellibrand estuary floodplain.

 

The Princetown Community know that the flood risks are far greater than the GHD report suggests.

Our concerns are that the floods witnessed by the community, and those reported by previous generations, are far worse than those used for assessment in the GHD reports.

The GHD reports also ignore the extensive official flood related data over much of this catchment instead relying on merely 8 years of flood level data from one gauge. Evidence indicates that actual flood hazards are far worse than the assumed flood hazards in the GHD hydraulic reports.

 

Matt Hayes’ review clearly shows that the GHD report uses rapid assessment approximations and not in-depth analysis and therefore the findings are indicative only and certainly not suitable to support a planning permit application.

 

The GHD report itself says that it shouldn’t be used beyond its stated purpose, which doesn’t include the determination of planning decisions, risk assessments, emergency management or construction around flood events. It says it should be used with caution and only by people who understand its uncertainties and limitations, which are not discussed in the report so how can Council claim to understand them?

 

The community believe that the Corangamite Shire are passing inadequate reports and that State planning policies that direct development away from hazardous floodplain areas, that consider sea level rise and increased storm surge events, are being ignored. The Council is obligated to observe the conditions of the planning permit

 

We take comfort from Mr Hayes’ review because it confirms what we know to be true, that the Gellibrand Estuary is not a safe place for a busy tourist resort. We welcome visitors but we want them to be safe.

 

We’re worried this proposed development will expose hundreds of visitors to ever increasing flood and storm surge hazards on a flooding site with only one access road that also floods. We are concerned about the certain flood damage to proposed public infrastructure. Not only will the public purse most likely be paying to build this public infrastructure, there will be an ever increasing cost to repair damage caused by the predicted increased flooding and storm surge events. Currently the low intensive usage, camping and cricket ground, is resilient to flood damage and is low risk to people.

 

The community are not against development but have said from the onset that this flooding site is not appropriate for this scale of development. Any sensible person can see that the development creates an unacceptable flood risk and at a minimum the Planning Permit and its reports should properly assess and guarantee public safety, which they do not.

The Corangamite Shire is obligated to observe the conditions of the planning permit but is desperate for any development at any costs and it seems there has been a failure to properly assess the risks of this proposal. Public safety demands that we question the Council processes of assessing the risks to life and property and the statutory gaps that have allowed this proposal to proceed so far without the requirement of a comprehensive and detailed hydrological study of the Gellibrand floodplain.

The Floodplain Management Perspective

  • State planning policies set out in the Victorian Planning Provisions require best practice to manage environmental risks like flooding and climate change. The GHD reports fall a long way short of best practice.

  • The 1% probability flood level provided by GHD and used to design the tourist resort is assumed and not supported by any evidence or modelling.

  • The 1% probability flood magnitude provided by GHD is greatly underestimated, as confirmed by a freely available online Regional Flood Frequency Estimation Model (https://rffe.arr-software.org/) provided by Australian Rainfall & Runoff, who also provide the most widely used best practice flood estimation guidelines for Australian engineers.

  • The influence of tides and storm surge on catchment flooding is overlooked in the GHD reports.

  • Climate change and sea level rise create coastal hazards that will over time transform the Gellibrand estuary. Any structure within the estuary that’s not designed to withstand these hazards and transformations will suffer damages. The GHD reports do not meet State government requirements for Local Coastal Hazard Assessments which must investigate concurrent storm tide and catchment flood events. Additional coastal hazards such as unstable cliffs and the formation of the sand bar at the river mouth which are unique to the Gellibrand estuary have also not been studied or assessed.

  • The planning permit for this tourist development does not guarantee public safety and the GHD report is very clear that neither do its findings.