Low sand levels prompt beach work

Contractors will be undertaking urgent work on St Clair Beach this morning, as sand below the sea wall has again reached dangerously low levels.

The work aims to prevent a repeat of last year's event, when several large sinkholes opened on the Esplanade - some large enough to swallow park benches.

The sinkholes appeared in late May after the area was pounded by heavy seas and high tides, which sucked sand from behind the sea wall.

Dunedin City Council staff have been keeping a close eye on sand levels since.

DCC roading maintenance engineer Peter Standring said Fulton Hogan staff would remove the last section of the St Clair Surf Life Saving Club's former access ramp at low tide this morning.

The remaining section of the boat ramp appeared to have been contributing to significant sand depletion around the seawall in that area, he said.

The latest sand monitoring results showed levels had dropped by up to 1.5m in specific areas over the past fortnight.

It appeared the sand, which helps protect the seawall, was being stripped back by the prevailing high tides at this time of year, he said.

''There is no indication that there is any further risk to the sea wall at this point and it is expected that, as has occurred in the past, the sand will return when the season and currents change.

''While sand levels do come and go on the beach, they are now at a level along the north end of the beach that requires some intervention.''

Mr Standring said an area of the beach would be cordoned off at times to enable machinery to be brought on to the site safely.

Barriers would also be installed on a section of the promenade to ensure the safety of both contractors and the public.

He said it had always been the DCC's intention to remove the remainder of the ramp, but the recent depletion of sand meant it needed to occur now.

He emphasised the volatility of the marine environment and the need to respond appropriately.

-john.lewis@odt.co.nz

The dismal tide of pessimism

Dunedin Dave: Why would the existing sea-wall need to to be extended? John Wilson Ocean Drive and the other sand dunes have achieved their purpose for about 100 years with only very occasional maintenance needed.

What erosion are you worried about? Do you think all the sand will disappear? On occasions we have had big seas remove some sand from some places, but this is a manageable problem - the proof is there for you to see. Also the DCC has data that shows that there is no long term trend of the St Clair sand level decreasing. The level varies over time but the trend is steady. The DCC claims that the failure of their new wall (which caused the St Clair sinkholes) was because of the low sand level, but sand levels as low as that have been numerous over the last 100 years. The old sea-wall was designed to cope with low sand levels, but it seems the new sea-wall wasn't.

There is no erosion, and St Clair is safe from the sea. I say that because any Councilor that allowed the sea to return would be quickly unelected by the citizens and property owners of the affected area. You talk about needing a "huge sea-wall" as if you actually believe everything your are told about rising sea levels. There are various ludicrous claims; some say the sea will rise 1 metre in the next 100 years. The actual measurements (tide gauges) show that globally the sea level is rising at only 17 cm per 100 years and there is no sign of any human influence. The rate of sea level rise is small and will get smaller until we get hit by the next ice age. [Abridged]

St Clair

Jeez Dave, that's a pretty strange way to look at St Clair. Reclaimation is as old as the oldest profession. The esplanade is iconic. I can show you pics taken in the 1950s of me there! The 60s, surfing. A seawall won't affect any other part of the beach, it's just that it hasn't been designed to take in slightly higher tides or the physics of them. The dunes are also iconic but they are not inhabited. John Wilson Drive does protect that part of the dunes as a cap but it's not a really nice place to spend a few hours, unless you are an albatross wanting to take off. The old salt pool? Fond memories. [Abridged]  

Visual mess

I take on board that others have sea walls but have you really understood the size and length that such a wall would need to be to work. Also all they do is move the erosion further along the coast.I think you forget that St Clair is reclaimed land as as such is always on borrowed time. How visually stunning will it be with a huge sea wall holding back the ever coming tide. St Clair as a place to walk and have a coffee would remain as would the view but just minus a beach which should you walk a few hundred meters up the coast will still be there! Maybe we should take a lesson from King Canute as in the end he worked out the use of trying to hold back a tide. Feel free to Google the story if it helps.

St Clair is a visual masterpiece

I agree, craypot: St Clair and its beach are worth keeping. As a way of convincing Defeatist Dave that sea-walls are common and effective, here are very many pictures of sea-walls in many countries »Google: "sea-walls"«. Dave can count them if he wants, but the point should be obvious: sea-walls that were not designed recently by the DCC are successful, durable, long lasting and numerous. Sea-walls stop coastal erosion and allow us to create pleasant and useful places.

The DCC has given us a bunch of feeble excuses for the 2013 St Clair sinkholes: things like "the sea did it", "sea-walls don't work" and "its the volatility of the marine environment". I think we know why they say those things. Defeatist Dave and our DCC councilors and staff don't need Google to find an outstanding example of a successful, durable and long lasting seawall, they just need to remember that the last St Clair sea-wall lasted about 100 years (and mostly it is still intact). 

[Abridged] 

St Kilda or St Clair?

Dave: Sea walls are not new. Try the east cost of the USA, Britain, France, anywhere you care to look are successful sea walls. Some face the Atlantic, a far more  formidable swell set than that of the Otago Coast. They all have one main feature - a secondary wall to reduce the vacuum effect and defuse the big bouncers.  Anyway Dave, St Kilda? Really? Nah ... No view of the sea, wind blown, and just not a nice place to be.. No cliff features, backdrop, no lovely architecture, no safe swimming ,no wow factor ... It's one thing having sand in your sandwiches, but in the car as wel ? Nah.

Important why?

I would say St Kilda redeveloped would be far more 'important' than St Clair is at the moment. What is it that makes it so worthy of saving the beach? Sure, a few cafes are located there, but would people still come to them if the beach was not there? I would say yes, as the last time I looked the coffee set were not dressed for the beach!
I think people would prefer an area redeveloped that was not going to be washed away and continue to cost more than its worth. As for sea walls, I think you are dreaming big. The 'wall' would need to run the entire length of the beach to even stand a chance, and all it would do is shift the problem along the coast! Could this be a case of 'demolition by neglect'? Oops sorry, different story.

Something is wrong

St Clair is a visual masterpiece, What I cant understand is why the DCC are involved at all. Here in the North a portion of our rates is given to the "environment section " ie Environment B O P.. and it would be under their budget that the stabilization would come from. To my way of thinking this is a problem they should be sorting out, not the DCC.. St Clair is a very important part of Dunedin, and it's got to be put right permanently. They do seawalls very well elsewhere in the world. [Abridged] 

 

Give up

Why bother? As has been the case in many UK coastal areas land erosion from the sea can not and will not be stopped. Maybe the time has come for the cessation of this fruitless fight. it was always going to be the case that eventually the sea would win. Give up wasting our money. And yes, I realise we would lose the beach but it was never meant to last forever. Let's just all move down to St Kilda beach and re develop that area. Plenty of parking, nice drive along the front, loads of space for coffe shops and cafes and sand enough for all. Again, we live in the past. Move up the road and move on.

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