Port Macquarie-Hastings Council is urging community members to have their say once the North Brother Flood Study goes on public exhibition from July 13.
Since the North Brother Local Catchments Flood Study was completed in 2019, council has engaged consultants Jacobs Pty Ltd to undertake further investigative works.
This includes a floor level study and above flood level flooding risk assessment, associated with a flash event originating from the mountain catchment.
As a first step in identifying and prioritising the risks to property and life associated with the flooding identified, the floor level survey for selected properties in the study area identified 270 buildings at risk of potential high hazard flooding during a one in 100 year local storm event.
Port Macquarie-Hastings Councillor Lisa Intemann said the study is just one stage of a very long process which looks to address the the risk associated with overland flooding from the North Brother Mountain in the Camden Haven.
"It's very important for the community to be aware of this (study) and to see those locations that might be affected by stormwater minimisation measures," she said.
In the past some Camden Haven community members have raised concerns the mapping will be utilised by insurance companies to calculate and determine policies.
Camden Haven resident Simon Hancox said his biggest concern is the large volume of residents who would be impacted as a result of the mapping, in comparison to those who have directly been impacted by major storm events in the past.
"The question that no one from council could answer when I attended the meeting, was how many physical properties had damage caused or high volume impact from these events? (one in 100 storm events)," he said.
Mr Hancox estimates only a very small number of properties would have actually been damaged by these incidents.
However, he said if hundreds of properties are included as part of the flood mapping, it could have negative consequences for residents in terms of sale prices and home insurance payments.
Cr Intemann said insurance companies don't solely rely on mapping to determine polices.
"They do their own assessment of risk," she said.
Cr Intemann said residents could benefit from the mapping because in the future council could carry out works to help minimise flood risk to properties.
"If risk is reduced (by council), that means their (residents') risk is reduced," she said.
For risk assessment and modelling purposes, the floor level of all remaining properties in the study area (those located clear of modelled high hazard flooding) were estimated to be 200mm above the height of the ground level at the building.
Mapping of above floor level flooding illustrates priorities for flood mitigation works by identifying vulnerable properties and areas within the catchment.
Of interest, the mapping illustrates the following:
- 462 residential properties are at risk of habitable floor flooding during a 1 in 100 year storm event in the catchment,
- A further 31 non-residential/commercial properties are also modelled to be subject to inundation of habitable floor levels during a 1 in 100 year storm event.
- More significantly, and in reflection of the scale of inadequacy of existing infrastructure and controls, 161 residential properties and 10 non-residential/properties are identified as being at risk of over floor level flooding during a comparatively common storm event.
Properties identified as being at risk of above floor level flooding are not confined to one area, and are spread throughout the catchment, demonstrating that multiple solutions of varying scales will be required to manage significant stormwater related issues impacting the catchment.
Sensitive properties and critical infrastructure within the study area have also been identified and mapped.
This includes schools, pre-schools, aged care facilities and emergency services.
An initial priority list of 16 key locations for flood mitigation works are:
1. Black Swan Terrace, West Haven
2. Ringtail Close and Sirius Drive, Lakewood
3. Lilli Pilli Close, Lakewood
4. Mission Terrace, Lakewood
5. Kirmington Terrace to Pelican Court, West Haven
6. Flinders Drive Estate, West Haven
7. Tunis Street Overland Flow Path, Laurieton
8. Quarry Way Overland Flow Path, Laurieton
9. Lake Street at Seymour Street, Laurieton
10. St Joseph's School, Laurieton
11. Harbourside Crescent Villas and Bold Street, Laurieton
12. Norman Street and Mill Street, Laurieton
13. Sirius Drive, Honeysuckle Avenue and Mahogany Close, Lakewood
14. Elouera Place, West Haven
15. Sandpiper Close, Lakewood
16. Ocean Drive East of Hoschke Road, West Haven
A spokesperson from council said nothing is off the table when it comes to residents giving their feedback on the study.
Council is appealing to residents to make a submission, or phone staff directly to give their feedback once the study goes on exhibition from July 13.