A new flood study has identified five drainage hotspots in Lennox Head and recommended a $390,000 mobile pump among the highest-priority options for reducing damage to properties.
Ballina Shire councillors will consider putting the draft study and associated flood mapping on public exhibition at their meeting tomorrow, Thursday, October 22.
Prepared by consultants Water Modelling Solutions, the study examines flooding caused when intense rainfall overwhelms drainage systems, sending stormwater across roads, reserves and private properties.
It identifies problems around Daintree Drive and Byron Street; Dodge Lane and Megan Crescent; Pacific Parade and Barrett Drive; the Park Lane–Ballina Street area; and Hutley Drive and Caloola Road.
The causes include insufficient pipe and culvert capacity and inadequate routes for water to escape overland when drains cannot cope.
A mobile, tractor-driven pump at Tresise Place is rated a high priority, with an estimated capital cost of $390,000. Its preliminary benefit-cost ratio of 6.15 indicates estimated reductions in flood damage substantially outweigh its whole-of-life cost.
Extending trunk drainage outlets from Tresise Place and Rutherford Street is also rated a high priority, with construction estimated at $1.4 million.
However, endorsement for exhibition would not approve construction or funding. The report says individual projects would require further investigation, design, approvals and budget consideration.
The findings also have implications for development assessments, with Council currently lacking adopted overland flood mapping for Lennox Head.
‘This mapping is particularly important for infill development in older urban areas where overland flow paths are inadequate or do not exist,’ the staff report states.
‘Development that blocks, obstructs or redirects overland flow can increase flood risk for the site and nearby properties.’
Adopting the study would provide information for applying existing development controls. Changes to those controls would be considered separately.
The modelling was checked against the March 2022 flood, which had a greater impact on the study area than the February event.
It also tested drainage outlet blockages, elevated ocean levels and climate change assumptions. Sand and debris can restrict coastal outlets, backing water up through the drainage system.
The study complements separate investigations into regional flooding from North Creek and coastal inundation.
Council received 33 community responses during its initial information-gathering stage.
If councillors endorse exhibition, residents will be able to inspect the draft report and maps, make submissions and attend a public information session with Council staff and the consultants. The findings would then return to Council for consideration before final adoption.
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