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HomeLatest NewsPick your poison: Wakehurst flood mitigation to come at cost

Pick your poison: Wakehurst flood mitigation to come at cost

Northern Beaches residents are being asked to choose between flood mitigation measures along the Wakehurst Parkway or protection of vulnerable species along the green corridor.

Wakehurst Parkway is a major state-run arterial road. The section between Narrabeen and the relatively new Northern Beaches Hospital is closed by flooding about six times a year, which has caused considerable community angst, particularly since the closure of Mona Vale Hospital.

A new state-funded study on options for flood mitigation along the stretch of road has been undertaken and, in the words of Mayor Michael Regan, shown there are “no easy or quick fixes.”

“The road runs through the middle of a sensitive, rich ecosystem supporting an array of threatened plants and animal species, and there are no options that fix the wider flooding problem without environmental impacts,” the Mayor said in a statement.

The feasibility study mentions the proposed works would potentially impact on a dozen species identified as threated under the Biodiversity Conservation Act 2017, including Black Bittern, Eastern Osprey, Glossy Black Cockatoo, Powerful Owl, Sooty Owl, Southern Myotis, Eastern Freetail Bat, Eastern Bentwing Bat, Grey Headed Flying Fox, Red Crowned Toadlet, and several other species of bat.  Some of these species are also likely to be affected by plans to widen Wakehurst Parkway on the southern stretch at Seaforth, according to the Beaches Link Environmental Impact Statement (EIS).

But concern over safe and speedy access to the area’s only emergency hospital,  and general commuter frustration,  has been a long-standing issue in the electorate.

Funds are there, but environmental concerns remain

The NSW Government announced in November it would allocate a further $13.1 million to reduce the frequency of flooding along Wakehurst Parkway, with Council to manage the project if it goes ahead.

Northern Beaches councillor Sue Heins said it was a difficult decision to make.

“We really, really need to hear from the community on their feedback on this particular item. We need to know what you value more,” she said at the recent Council meeting. “It’s an opportunity to close [the Parkway] from 6 to 7 times a year to once in every two years…

“We need to know what you value more – the opportunity to drive down the Wakehurst Parkway more or saving the environment that will be affected.”

The feasibility study is expected to be available for community input in May (links to documents in interim provided at the end.)

A done deal?

While Council says it will only go ahead with community support, previous Council communications regarding the project has represented the flood mitigation as a fait accompli. A Council media release from November last year said that the government’s funding offer of $13.1 million meant works were “a step closer”.

“This initiative is the result of a fantastic partnership between Council and the NSW Government and particularly local MPs Jonathon O’Dea, Rob Stokes and Brad Hazzard who have been instrumental in ensuring this project comes to fruition” the statement read.

However, community support is one of the conditions Council has voted as a requirement in order to accept the government funding.

The details

A previous study in 2017 looked at raising Wakehurst Parkway in key locations and corresponding culvert (underground pipe) upgrades appeared to provide a longer-term sustainable option to permanently reduce the incidence of flooding and road closures in larger flood events. However, it was found to have a significant capital cost and major environmental impacts. “The raising of Wakehurst Parkway is not under further investigation and was discounted as an option from this assessment,” the new study states.

The new study looks at various options for three flood prone sections of the Parkway – at “The Bend”, Oxford Falls and the sports centre (Academy). While there are seven options provided for the bend, Oxford Falls options require increasing the capacity of the culvert (a bigger pipe underneath) and “bunds and localised low point drainage” (uh— hard to simplify this one, you’ll need to read the details) at the academy.

A map from the new feasibility study shows the points along Wakehurst Parkway that a re prone to flooding.

The new study does not include any detailed construction costings as this could compromise market pricing should Council proceed to tender the project (all costs mentioned in this report and inclusive of overheads such as project management, design, offsets, construction and contingency costs).

In the executive briefing to Council, the recommended approach was Option B4 (new levee, removal of 1m depth of overbankk sediment, under the road culverts, and top up of existing levee; 02 Culvert capacity increase (so it floods only once every two years) and S1.

“The environmental impacts are significant, however it is considered the combination of Options B4, O2 and S1 provide best flooding outcome for the available funding [roughly $17 million]. The significance of the environmental impact and how this can be mitigated will need to be determined through subsequent approval processes,” it states.

The Wakehurst Parkway Flood Mitigation Feasibility Study will be uploaded onto Council’s Have Your Say in May, but in the interim is also accessible under 23 March meeting documents under ‘attachments’. https://www.northernbeaches.nsw.gov.au/council/meetings

 

 

 

 

 

 

 

 

 

 

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