Northern Beaches Council To Consider Extending Collaroy Seawall

Jake Lapham
Swellnet Dispatch

It's been labelled an "abomination", the "ugliest edifice built on the coast".

And, it might be about to get bigger.

A group of beachfront home owners are pushing to extend the controversial Collaroy seawall on Sydney's northern beaches. A Development Aplication (DA) before Northern Beaches Council would see two additional sections of vertical wall built — 50 and 30 metres in length — straddling the South Narrabeen Surf Club.

The first 210-metre stretch of wall to protect from erosion was built in 2021 (ABC News: Jake Lapham)

The applicants hope the seven-metre high structure will protect their homes from the types of swells seen in 2016. That event saw a swimming pool topple into the ocean and frantic sandbagging to prevent luxury beachside properties from collapsing.

It was the catalyst for the construction of the first 210m stretch of seawall in 2021. At the time, some locals feared the wall would come at the expense of beach amenity, describing it as "totalitarian architecture", an "abomination" and the "ugliest edifice built on the coast".

Beachfront homes were damaged in the 2016 weather event (AAP: Dean Lewins)

Those concerns still linger today. The new proposal would guard five beachfront properties but leave the area in front of the South Narrabeen Surf Club without the same protection.

Erosion in front of the club has already been so serious that lifesavers have been unable to launch boats, potentially impacting the ability to conduct rescues.

"The neighbouring surf clubs on either side of South Narrabeen, have to come up and support the lifesavers there with their rescue craft and it's not always an effective option," Surf Life Saving NSW chief executive officer Steven Pearce said.

Angus Gordon, a Narrabeen-based coastal engineer, said additional measures would be needed to protect the surf club if the vertical wall goes ahead.

Coastal engineer Angus Gordon says the surf club will need extra protections put in place (ABC News: Jake Lapham)

There are concerns the new structures could pose a greater risk to the surf club (Image: Simon Beardsell, Graph: ABC News)

Without them, "it would mean that the area where the club is here would erode more than normal, so you'd get a double whammy from the two walls".

Northern Beaches Council dismissed suggestions it would approve work that would threaten the surf club. A spokesperson said it was "absolutely planning capital works" to protect the surf club, but is awaiting the outcome of the DA for the wall extension.

Richard Barnes is one of the landowners behind the DA and is prepared to spend $250,000 to build his section of wall. He purchased the property from his great aunt when she died in the 1980s, and is in the process of constructing a new house on the block.

"We do have a right to protect our houses, everyone has that right," he said. But he concedes it's a "lot of money" to pay for the luxury of living with the ocean on his back doorstep.

"In the value of the property, it's a worthwhile investment."

Richard Barnes is among the residents behind the development application (ABC News: Jake Lapham)

Eighty per cent of the total cost is being funded by residents, with the remaining twenty per cent split between the state government and local council.

Local surfer Terry Fitzgerald is among those concerned about the effect the vertical structure could have on the beach and surf.

"It all revolves around the movement of sand up and down the beach, and the effect of the lack of sand in the wave action zone on the surf itself," he said.

But the wall's engineer, Peter Horton, said the choice of a vertical or sloping wall makes "little difference" to the impact on the beach.

"The proposed seawall will not interact with waves for most of the time, so can hardly be expected to significantly alter the beach profile," he said.

Terry Fitzgerald is concerned about the impact on the beach and surf (ABC News: Jake Lapham)

Kristen Splinter is a coastal engineer with the University of New South Wales's Water Research Lab, which has been studying the coast at Collaroy for more than forty years.

"With any beach, and Narrabeen's no different, we see periods of erosion and times when the beach comes back again," she said. "[After the 2016 event] that beach naturally did recover a lot within a year."

The creep of the Collaroy seawall raises difficult questions about coastal management more broadly.

"This ocean isn't going to stop coming just because you build a wall, it will eventually go over the top and where are we then?," Mr Fitzgerald said.

The Newport Surf Club is also exploring plans to construct its own seawall.

Dr Splinter conceded it's an invidious decision for policymakers. "Do we either retreat and allow a beach to naturally take its course, but that obviously has a cost potentially involved with it and politics," she said.

"Or do we find a way to hold the line, and that can be a variety of different engineering solutions from beach nourishment out to more hard structures as we're seeing in Narrabeen right now."

A council spokesperson could not give a time frame on when a decision would be made.

//JAKE LAPHAM
© Australian Broadcasting Corporation. All rights reserved.

Comments

thermalben's picture
thermalben's picture
thermalben Sunday, 18 Sep 2022 at 1:14pm

Yikes.

DudeSweetDudeSweet's picture
DudeSweetDudeSweet's picture
DudeSweetDudeSweet Sunday, 18 Sep 2022 at 2:55pm

Says local flog: "We do have a right to protect our houses, everyone has that right," he said. But he concedes it's a "lot of money" to pay for the luxury of living with the ocean on his back doorstep. In the value of the property, it's a worthwhile investment."

But….your property value should account for the fact that’s it’s position is not naturally viable and be priced accordingly.

You reckon the council and state will chip in 20% when I decide to build a forty metre high, fireproof steel wall on the public land around my place to secure me from bushfires, snakes and rubber necking tourists?

Seems to be all cool down Collaroy way.

velocityjohnno's picture
velocityjohnno's picture
velocityjohnno Thursday, 22 Sep 2022 at 6:59pm

The value of coastal property increases the closer you get to the sea, until it passes over the event horizon and becomes the sea.

bbbird's picture
bbbird's picture
bbbird Sunday, 18 Sep 2022 at 4:00pm

NSW coastal beaches, rivers and estuaries to the mean high tide mark, are the property of the Crown (i.e. NSW State Govt).

If they built a demountable wall est. 10m westward, to allow for projected sea level rise and related storms....(off crown land), they could fish from their lounge room.

"Title to the bed of all other tidal waters is vested in the Crown, i.e. 'The State of NSW', under the control of Crown Lands on behalf of the Minister Administering the Crown Lands Act 1989. An exception is those tidal waters (and any inter-tidal zone) vested in the Minister Administering the National Parks and Wildlife Act."

Locating or relocating tidal boundaries:
The following points must be observed by a surveyor when locating or relocating a parcel boundary defined by the MHWM and when showing that boundary on a new plan of survey:
reference to 'high-water mark' (or other boundary of land that abuts tidal water) in a previous plan of survey is taken to be reference to 'Mean High Water Mark' unless otherwise stated - cl.51 Surveying and Spatial Information Regulation 2012.

the description and relationship to the MHWM of any sea wall and reclaimed land must be shown in a new plan of survey -
cl.51 Surveying and Spatial Information Regulation 2012.
the landward boundary of an existing reservation of stipulated width fronting tidal waters which has not been previously defined by survey must be defined by right lines approximately parallel to the MHWM as originally defined
- cl.48 Surveying and Spatial Information Regulation 2012
https://rg-guidelines.nswlrs.com.au/deposited_plans/natural_boundaries/t...

https://www.valuergeneral.nsw.gov.au/__data/assets/pdf_file/0008/216980/...

Reference: 2022 Report Below
https://oceanservice.noaa.gov/hazards/sealevelrise/sealevelrise-tech-rep...

1. Sea level along the U.S. coastline is projected to rise, on average, 10 - 12 inches (0.25 - 0.30 meters) in the next 30 years (2020 - 2050), which will be as much as the rise measured over the last 100 years (1920 - 2020).

2. Sea level rise will create a profound shift in coastal flooding over the next 30 years by causing tide and storm surge heights to increase and reach further inland. By 2050, “moderate” (typically damaging) flooding is expected to occur, on average, more than 10 times as often as it does today, and can be intensified by local factors.

3. Current and future emissions matter. About 2 feet (0.6 meters) of sea level rise along the U.S. coastline is increasingly likely between 2020 and 2100 because of emissions to date. Failing to curb future emissions could cause an additional 1.5 - 5 feet (0.5 - 1.5 meters) of rise for a total of 3.5 - 7 feet (1.1 - 2.1 meters) by the end of this century.

JamesC_PL's picture
JamesC_PL's picture
JamesC_PL Sunday, 18 Sep 2022 at 4:13pm

Hard to believe this is being considered! This will lead to nothing but disaster. Seawalls will continue to result in the beach downstream of them being completely eroded, as the first collaroy seawall has proven. Extending the seawall will only result in more aggressive downstream scour, which will then start impacting Narrabeen beaches. The best solutions here are sand renourishment (eg Noosa & Snapper) or Groynes (Apollo Bay, Kirra, Point Lonsdale). Groynes dont look as good, but are a cost effective long term solution, and will bring back sand to not only protect the beach but also create waves. We have been fighting this battle at Pt Lonsdale for a few years now and can put you in touch with experts to advise if required. Seawalls are NOT the answer!

bbbird's picture
bbbird's picture
bbbird Sunday, 18 Sep 2022 at 4:17pm

seawalls
Let us consider a given a stretch of sandy coast. A very severe storm surge will cause a rate of mainland erosion of say 40 m in case the stretch of coast is unprotected. With a seawall which is able to withstand these conditions the erosion of the mainland will be zero. (In front of the seawall a deep scour hole will be formed.) When the entire seawall keeps its integrity; no further problems arise. (The scour hole will be re-filled again after some time with ordinary boundary conditions.) If, however, the seawall partly collapses and locally a gap in the seawall is formed during the severe storm surge, a rather dangerous situation will occur.......

Large volumes of sediment from the mainland are able to disappear through the gap and will flow along the sections of the seawall which are still in good condition in both longshore directions adjacent to the gap, filling the scour hole. It is expected that the ultimate rate of erosion of the mainland behind the gap will be larger than the 40 m as mentioned for the unprotected case.
http://www.coastalwiki.org/wiki/Seawalls_and_revetments

bbbird's picture
bbbird's picture
bbbird Sunday, 18 Sep 2022 at 5:01pm

Projected Coastal Erosion maps in this section of coast on pages 44 & minimum setbacks for property p 54
https://files.northernbeaches.nsw.gov.au/sites/default/files/finalczmpfo...

flollo's picture
flollo's picture
flollo Sunday, 18 Sep 2022 at 5:10pm

Madness

bbbird's picture
bbbird's picture
bbbird Sunday, 18 Sep 2022 at 5:33pm

Existing Colleroy seawall 1.3km length cost $25M (or $19 000 / metre)
(State & L.Govt) paid 20% of the costs= $5M
50 X property owners paid $400,000 ea

NSW coastline is 2,137 km long......
only cost $41,096,153,846 to do the lot to the Qld & Vic boarders...at 2021 building costs.
https://en.wikipedia.org/wiki/Geography_of_New_South_Wales

Thegrowingtrend.com's picture
Thegrowingtrend.com's picture
Thegrowingtrend.com Sunday, 18 Sep 2022 at 9:04pm

How about a wall around Council Chambers.

bonza's picture
bonza's picture
bonza Sunday, 18 Sep 2022 at 10:55pm

Unsurprising but bloody depressing.

indo-dreaming's picture
indo-dreaming's picture
indo-dreaming Monday, 19 Sep 2022 at 8:25am

Looks like a prison wall.....i can't believe its not tagged with graffiti though.

So happy not to live near a city.

matts's picture
matts's picture
matts Monday, 19 Sep 2022 at 12:39pm

There are surveillance cameras installed at every section of the wall. For the very purpose of catching any taggers!

Sheepdog's picture
Sheepdog's picture
Sheepdog Monday, 19 Sep 2022 at 3:47pm

Jaysus H Christ do i have to fix everything around here?
Not only would my diagram below fix the erosion for the Multi millionaires, It'll increase the house prices, with a series of utterly incredible surf breaks rivaling anywhere in the world. And on flat days, the fishing will be great!
Just name the best left "Sheepdogs" is all I ask.

lilas's picture
lilas's picture
lilas Monday, 19 Sep 2022 at 5:14pm

@sheepdog Even though I think artificial reefs such as your design are the way forward, apparently there are a lot of undersea cables along Collaroy [as noted previously by someone on the forums] so unfortunately it's almost impossible that any changing/construction of the seafloor will be allowed to happen here. Would have been a great test case but alas, somewhere else will have to be first.

thermalben's picture
thermalben's picture
thermalben Tuesday, 20 Sep 2022 at 7:34am

As I wrote last year (link below):

I'm not entirely sure, but one of the reasons why an offshore reef structure hasn't been considered for Narrabeen may be because it's part of the Northern Sydney Protection Zone, hosting submarine cables that connect Australia to various parts of the Pacific (including Japan).

Amongst other things, it is illegal to "establish, maintain or use a spoil ground or other ocean disposal point (including dumping materials at sea)".

https://www.swellnet.com/comment/772908#comment-772908

warddy's picture
warddy's picture
warddy Tuesday, 20 Sep 2022 at 3:41pm

I could look it up but easier if somebody else does it for me …
What’s a submarine cable designed for?
Isn’t everything WiFi now ….
Maybe a war thing then ..

thermalben's picture
thermalben's picture
thermalben Tuesday, 20 Sep 2022 at 4:00pm

WIFI range is generally <100 metres.

If you need to connect devices over greater distances than 100m, it is recommended to use ethernet cable.

If you need to connect countries, then you'll need an undersea fibre optic cable.

warddy's picture
warddy's picture
warddy Tuesday, 20 Sep 2022 at 4:35pm

Mmm thanx for the update …
Thought there was something called satellite but maybe I’m mistaken …

thermalben's picture
thermalben's picture
thermalben Tuesday, 20 Sep 2022 at 4:37pm

Sure, for (relatively) small volumes of data traffic that don't mind high latency and occasional outages.

Won't be long and I'll need to order my own private undersea cable for the sheer amount of bandwidth required to entertain my kids in the evening.

steveb's picture
steveb's picture
steveb Friday, 23 Sep 2022 at 8:05am

Hi Ben,
Throughout my career I have had experience in planning and undertaking civil works in the vicinity of major underground services, ie HV elect mains /HP gas mains/co-ax/optic fibre/other comms, you name it.

I see no reason why reefs cannot be located adjacent to undersea comms cables in just the same way as those cables are adjacent to other engineered structures on land. The services are located and designed/worked around and protected during the works.

The sea-dumping you refer to relates to old ships, barges, train carriages and the like which from time to time have been disposed off the coast. “Dee Why was scuttled on 25/05/1976, becoming the first ship to be part of the artificial reef off Long Reef. Today she rests in one piece, upright, at a depth of 51 metres”. https://www.facebook.com/FerriesOfSydney/posts/dee-why-was-the-first-of-....
I believe there were many items dumped in the Long Reef area, and to protect the cables it is now prohibited, rightly so, to dump in the Protection Zone.

As I have said before on this issue, I don’t believe the existence of the subsea cables will preclude siting reefs off Collaroy.

Reefs are the only option which will widen the beach and keep the sand there without any structures being visible on the beach, the sooner this option is seriously considered the sooner "the walls" controversy will be buried, in all senses of the word.

Cheers

thermalben's picture
thermalben's picture
thermalben Friday, 23 Sep 2022 at 8:07am

Yep, I agree totally.

Sheepdog's picture
Sheepdog's picture
Sheepdog Friday, 23 Sep 2022 at 12:04pm

Heaps of room for some artificial reefs, Ben.
2 other points;
The cables WILL need replacing one day.
And. Has anyone correlated cable placement and erosion?

But here' your map, with ample room for 6 reefs, rights and 6 lefts all breaking in different conditions and ways. The economic boost in stamp duties would pay it off in 10 years

pcrisp's picture
pcrisp's picture
pcrisp Tuesday, 27 Sep 2022 at 3:43pm

yep and we have the system but the council won't listen

wax-on-danielson's picture
wax-on-danielson's picture
wax-on-danielson Monday, 19 Sep 2022 at 5:35pm

I thought it was scientifically proven a big A-Frame reef was the best way to stop beach erosion.. a la North Shore of Oahu where the surf is often 20 foot.

bbbird's picture
bbbird's picture
bbbird Monday, 19 Sep 2022 at 5:52pm

In NSW Artificial reefs are being designed for retired baby boomer fisherman & divers.
guest-amates $1M each.
https://www.dpi.nsw.gov.au/fishing/recreational/resources/artificial-reef
Start lobbying for your retirement reef Sheepdog

lilas's picture
lilas's picture
lilas Tuesday, 20 Sep 2022 at 5:56am

"But the wall's engineer, Peter Horton, said the choice of a vertical or sloping wall makes "little difference" to the impact on the beach.

"The proposed seawall will not interact with waves for most of the time, so can hardly be expected to significantly alter the beach profile," he said."
------------------------------------------------
Is this guy for real or what?
No offense, but can we please replace this fool and get someone who knows the ocean in charge of the show. What a complete farce!

Craig's picture
Craig's picture
Craig Tuesday, 20 Sep 2022 at 7:03am

Totally Lilas.

Re artificial reefs SD, and as Lilas pointed out, Ben noted in previous discussions the presence of submarine cables, so there's no way they'll be allowed.

What about a number of small groins like seen on the Gold Coast?

Slow the northward movement of sand (currently trucked to the southern end), build wider beaches and also increase the surf amenity,

It'd stop blocking Narra lagoon as well.

Is this viable?

monkeyboy's picture
monkeyboy's picture
monkeyboy Tuesday, 20 Sep 2022 at 1:19pm

Newport Beach too ? Noooooooooo. Bilgola Beach next (those properties on the front there are almost at sea level - a wall would block their view !

PAG's picture
PAG's picture
PAG Tuesday, 20 Sep 2022 at 3:40pm

are they going to give us the ratepayers stair access to the beach (wethrill st and others?)
so far the wall has destroyed the beach , would a sand pump from the lake to collaroy pool be better? (maybe it would make a superbank that isnt ugly )

velocityjohnno's picture
velocityjohnno's picture
velocityjohnno Thursday, 22 Sep 2022 at 6:58pm

Turning Japanese
I think they're turning Japanese
I really think so

(take it away Zen)

Crab Nebula's picture
Crab Nebula's picture
Crab Nebula Tuesday, 27 Sep 2022 at 2:00pm

A big wall like that reminds me of a Mr Bean episode when he was down at an English 'beach' trying get changed without exposing himself in front of the blind man.