2 March 2012

Thar she blows! New Cotter Dam overspilled

1 March 2012 | johnboy

The Cotter Dam Expansion Dam Cam is showing the worst case scenario of flood waters rising over the under-construction wall as the capacity of the river diversion is comprehensively overwhelmed.

Let’s hope the raging torrent doesn’t undermine the wall or this will become a disaster of 2003 bushfires proportion.

We certainly hope that doesn’t happen, but it’s not like this was meant to happen either.

UPDATE 01/03/12 09:10: Thanks to dpm for pointing us at the above video compression of the overspill

[Photo by Androo]

UPDATE 02/03/12 8:18: And she’s still going very strong this morning:

UPDATE 02/03/12 09:31: This in from ACTEW supremo Mark Sullivan:

MarkS
2012/03/02 at 8:21 am

This morning observations are that the dam structure is sound. Heavy machinery has remained safe and cranes are fine. Have lost some forms and scaffolding and some light equipment. Biggest concern is the washing out of earthwork on the downstream side (looking at damcam it is on the left abutment or the right hand side looking at the dam). Possibly be a week before we get back on the dam and looks like a three week clean up. Flood is a one in one hunred year event so top marks to the engineers. Now we wait till tomorrows renewed assault.

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HenryBG6:23 pm 03 Mar 12

dungfungus said :

HenryBG said :

shauno said :

I blame Tim Flannery for saying never again would we have our dams filled.

Tim Flannery said no such thing.

Please take care you don’t fall for fossil-fuel-industry-funded propaganda which is intended to “prevent science from being taught in the classrooms”, as recently leaked documents have revealed.

Depends what you mean by “science”

Suddenly the interests of academia and industry lobbyists collide ans post-modernist thinking gets a new lease of life.

Science is science. And liars hate science, because science proves them wrong, hence the big anti-science PR-campaign that’s on at the moment.

dungfungus5:58 pm 03 Mar 12

HenryBG said :

shauno said :

I blame Tim Flannery for saying never again would we have our dams filled.

Tim Flannery said no such thing.

Please take care you don’t fall for fossil-fuel-industry-funded propaganda which is intended to “prevent science from being taught in the classrooms”, as recently leaked documents have revealed.

Depends what you mean by “science”

dungfungus5:56 pm 03 Mar 12

Deref said :

Does anyone know what Lake George is looking like?

It looks wet, like any other lake.
When Lake George is empty, why isn’t it just called “George”?

HenryBG5:15 pm 03 Mar 12

shauno said :

I blame Tim Flannery for saying never again would we have our dams filled.

Tim Flannery said no such thing.

Please take care you don’t fall for fossil-fuel-industry-funded propaganda which is intended to “prevent science from being taught in the classrooms”, as recently leaked documents have revealed.

Deref3:51 pm 03 Mar 12

Does anyone know what Lake George is looking like?

steveu3:51 pm 03 Mar 12

Peekz said :

Surely this rain was factored in the to project schedule?

I am positive that rain was factored into the project schedule as is with most major construction schedules – but I dont believe the data was there to be able to throw this amount of rainfall on BOM’s crystal ball…

IYou would reasonably expect a reduction in our water prices now, since we have had so much of it lately? I mean it was put up becuase we had so little of it before (and our water quality is so good). Fat chance I guess.

I suppose we have to boost ACTEWS profits back somehow somehow for being so responsible when there was a shortage of water (and I do think Canberrans in particular have done a great job in being responsible, with the odd exception – and have had restrictions longer than most other states)

shauno9:27 am 03 Mar 12

I blame Tim Flannery for saying never again would we have our dams filled.

LSWCHP10:25 pm 02 Mar 12

Skidbladnir said :

MarkS said :

Flood is a one in one hunred year event so top marks to the engineers.

*grumblegrumblegurmble*

Annual 1% non-dependant probability.
There is a sixty something percent chance of a 1% annual flood risk being realised once or more in a 100 year period.

The water table around my place has risen above ground level, so I have some minor flooding under my house. The same thing happened about 18 months ago, when we had a very wet weekend that was also a once in (some number of years) weather event.

Seems like these once in 40/80/100/whatever year rain events are becoming quite frequent. 🙁

YetAnotherBlowIn8:39 pm 02 Mar 12

Mark Sullivan has tweeted this photo taken from the abutment above the new dam. You can’t see the tracks on the excavator in the bottom of the photo which makes the water, what, 1 metre deep?

gooterz6:49 pm 02 Mar 12

If the dam was built already this would have filled it?

buzz8196:52 am 02 Mar 12

Mr Evil said :

rohbo said :

Mr Evil said :

A couple of questions.

Why were vehicles left parked on the topside of the dam when there had been pretty ample warning that NSW/ACT was going to receive a lot of rain in the next few days, and numerous flood warnings had been publicly issued?

If you know how to get some very heavy machinery off a 40m high wall i’m sure ACTEW would love to hear from you. Mark S from ACTEW said they got off everything they could with the cranes and the rest was too heavy so had to stay.

Umm, maybe the same way they got them up there in the first place?

Anyway, maybe I should have expressed myself better – the really heavy stuff isn’t the problem, as obviously if a 40 or 60 tonne object is going to be swept off the wall by the overflow, then I would suggest that there’d be bigger issues to worry about with the dam itself at that point. It’s some of the other smaller vehicles that appeared to be still on the dam in the photo that Mark submitted earlier this morning.

The point I was making is that we have had several days warning that the rainfall was going to be high, but some people seem to have been caught slightly ill-prepared by it all.

And as to my comments about objects seen floating down the river; yes, I understand that there will always be plenty of stuff that is washed down a river in flood, as witnessed on LBG last time we had a flood like this – but isn’t it a good idea to try and ensure that if at all possible that we don’t add to the debris pile unnecessarily?

I love arm chair critics, while you are sitting at your computer sipping your latte, photocopying stuff that no one really cares about, these guys are out slugging their guts putting together a remarkable structure that is built to contain 78 gigalitres of water, I can’t even fathom how much that is.

They have successfully built it in such away that the integrity is holding after a heavy onslaught of rain, no one is injured, they have done everything they can to make it safe – there and down stream and you think you could have done it better.

Good work Mr Evil. *sarcasm*

This time, good work to the construction workers up on the dam. *sincere*

pandaman10:33 pm 01 Mar 12

Mr Evil said :

rohbo said :

Mr Evil said :

A couple of questions.

Why were vehicles left parked on the topside of the dam when there had been pretty ample warning that NSW/ACT was going to receive a lot of rain in the next few days, and numerous flood warnings had been publicly issued?

If you know how to get some very heavy machinery off a 40m high wall i’m sure ACTEW would love to hear from you. Mark S from ACTEW said they got off everything they could with the cranes and the rest was too heavy so had to stay.

Umm, maybe the same way they got them up there in the first place?

Anyway, maybe I should have expressed myself better – the really heavy stuff isn’t the problem, as obviously if a 40 or 60 tonne object is going to be swept off the wall by the overflow, then I would suggest that there’d be bigger issues to worry about with the dam itself at that point. It’s some of the other smaller vehicles that appeared to be still on the dam in the photo that Mark submitted earlier this morning.

The point I was making is that we have had several days warning that the rainfall was going to be high, but some people seem to have been caught slightly ill-prepared by it all.

And as to my comments about objects seen floating down the river; yes, I understand that there will always be plenty of stuff that is washed down a river in flood, as witnessed on LBG last time we had a flood like this – but isn’t it a good idea to try and ensure that if at all possible that we don’t add to the debris pile unnecessarily?

I could crap on about the capacity of those tower cranes, the likely weight of the equipment left on top and the likely difficulty in getting a big mobile crane anywhere near enough to be of any use, but with the know it all layman such as yourself it will never be of any use.

Suffice it to say, don’t give up your day job. Or if your day job is construction related, consider giving up.

On topic, damn that is some serious water. It’ll be interesting afterwards to see if any of the gear on top has moved. In any case, there’s going to be some damage to clean up and repair. Poor bastards. I saw photos from the first time they got flooded out and the place was a serious mess.

thatsnotme8:40 pm 01 Mar 12

Mr Evil said :

A couple of questions.

Why were vehicles left parked on the topside of the dam when there had been pretty ample warning that NSW/ACT was going to receive a lot of rain in the next few days, and numerous flood warnings had been publicly issued?

Was any attempt made to secure loose material on the worksite before it became apparent that the waters were going to breach the top of the current wall? Whilst watching some of the webcam footage an amount of timber and what appeared to be an upturned watertank could be seen floating down the river in front of the dam – what measures are taken to prevent this material flowing down the river to become a problem further downstream?

So just where were the vehicles supposed to go? There’s no road leading off the top of the dam – if it was as easy as just driving off the top, do you not think they would have done that? So the alternative is craning the vehicles off of the dam. I don’t profess to know anything about crane operations, but I’d imagine that lifting something like the vehicles that have been left up there wouldn’t be easy, or necessarily safe.

And honestly…timber floating down the river? Maybe a water tank? If you can manage to differentiate between what naturally flows over the dam in an event like this, and what may be construction material, based only on the dam cam images, then you’re obviously watching a different dam cam to me.

With no connection to this project at all, I think I can safely say that yes, there would have been significant efforts made to secure as much as possible on the site. Everything that’s lost down the river costs money, and I have enough faith in the people in charge of this project to believe that they’re not going to deliberately throw money away if it can be easily avoided. I’m sure this site has been a hive of activity over the last few days, preparing for the worst. Time will tell whether those preparations were good enough.

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