4 June 2012

Cracking at the Cotter Dam

| johnboy
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cotter dam

Some very interesting documents have been pushed into the light of day by the FOI process.

It begins discussing the damage caused by the flooding at the Cotter Dam but then takes an interesting turn when cracking is discovered, put down to the delayed concrete pour.

They were hoping it wouldn’t crack and now they hope they can ameliorate the damage, and that it won’t get worse.

Any of our readers with engineering backgrounds care to give their assessment?

cotter dam crack

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Gungahlin Al said :

Fondly rembering the pseudo-engineering debate over the bridge collapse… Back in my box.

I may not have a civil engineering degree or be up on the latest standards, but I suspect unprovoked collapse is a feature normally kept outside any project scope.

Gungahlin Al4:03 pm 05 Jun 12

johnboy said :

Gungahlin Al said :

Since when has the lack of an engineering background held some RA readers back from giving engineering assessments? 🙂

It was more a specific invitation.

I understand. I was just trying to make funny. Fondly rembering the pseudo-engineering debate over the bridge collapse… Back in my box.

neanderthalsis9:18 am 05 Jun 12

chewy14 said :

Cracks in the wall had to FOIed?

Well, that just about sums up how this government works these days it would seem.

Let me reiterate, cracks in the dam wall had to be FOIed.

Raising eyebrows?

Why?

Do you expect to be informed about every issue at every construction site in the ACT?

If they were cracks likely to lead to any sort of failure, you can bet the engineers would be calling for some very serious remediation works.

They probably didn’t want to make the information public because of exactly the sort of uninformed speculation you’re likely to see on this thread.

Under any normal process of government, the opposition or media would go to the relevant Minister and ask if the recent flooding caused any damage to the work and has there been an assessment of the costs to fix it. A normal government would say yes, there was some damage, we’re assessing it and it might set back construction.

Here in the ACT, however, the exchange would run something like:
“Was there any damage and what will it cost to fix it.”
“We’re not going to tell you.”
“Why not?”
“Nunya”
“Well, we’ll FOI it.”
“You do that.”
“We will.”
“Off you go then.”
“Right-ho.”
<<>>
“Oh, you did then, none of this is real and we’re not to blame” *runs and hides*

pink little birdie8:56 am 05 Jun 12

Jivrashia said :

Does anyone have an emergency response plan for in the case that it gets worse?

If not then…

Holden Caulfield said :

Run for the hills!

+1

Surely you want to be running away from the dam not towards it :-p

MarkS said :

Sorry for delay. Tied up on Grandfather duties. Document is a very technical report to regulator on the dam. I told Ross Solly about it a few weeks ago on breakast radio and will talk with Alex Sloan this morning. Cracks have been remediated and are now five metres under. Remediation involves cutting them out and placing fabric and reinforced steel over them. The cracks are local and will not expand through the dam. Grout lines will enable final closure.
We deal with concrete issues continually on the dam. Minor honeycombing is common. Again drill it out and repair. Biggest daily concern is the quality of the mix and our quality assurance processes are very strong (excuse the pun) and concrete is good
Dam is in good shape. These issues do not impact on our budget as they are an expected contingency. Rain over last two weekends only issue since restart but excellent work keeps us on schedule and budget (revised of course)
Report shows the very proper independent scrutiny and review involved in building a dam. Liked the thread

🙂 Thanks Mark.

Sorry for delay. Tied up on Grandfather duties. Document is a very technical report to regulator on the dam. I told Ross Solly about it a few weeks ago on breakast radio and will talk with Alex Sloan this morning. Cracks have been remediated and are now five metres under. Remediation involves cutting them out and placing fabric and reinforced steel over them. The cracks are local and will not expand through the dam. Grout lines will enable final closure.
We deal with concrete issues continually on the dam. Minor honeycombing is common. Again drill it out and repair. Biggest daily concern is the quality of the mix and our quality assurance processes are very strong (excuse the pun) and concrete is good
Dam is in good shape. These issues do not impact on our budget as they are an expected contingency. Rain over last two weekends only issue since restart but excellent work keeps us on schedule and budget (revised of course)
Report shows the very proper independent scrutiny and review involved in building a dam. Liked the thread

Reading the material gives me cause for concern. No doubt it was a significant storm event and no doubt there were risk plans in place. What the community will be wanting is reassurance that the cracking will not compromise the structure…. particularly for such a costly and high profile project?

justin heywood said :

chewy14 said :

….[If they were cracks likely to lead to any sort of failure, you can bet the engineers would be calling for some very serious remediation works.

LOL. Yeah right. We ARE talking about the ACT Government here Chewy – not exactly famous for their good management of large infrastructure projects, nor for transparency about their activities.

They’re not good on transparency, but they certainly don’t muck around with things like this.

When they found a massive gap forming between Corin Dam wall and the slip way due to uneven settling of the dam wall in the centre, they were very quick to initiate remediation works because of the genuine (though limited) risk of not only the dam failing, but of it causing a cascade failure. Very few people knew of this because the government kept it hidden.

justin heywood9:33 pm 04 Jun 12

chewy14 said :

….[If they were cracks likely to lead to any sort of failure, you can bet the engineers would be calling for some very serious remediation works.

LOL. Yeah right. We ARE talking about the ACT Government here Chewy – not exactly famous for their good management of large infrastructure projects, nor for transparency about their activities.

And no, I don’t think the dam will collapse either, but then again looking at the diagram above, I wouldn’t be camping downstream of it in flood times either.

angrymotorist1 said :

MarkS? Not so quick to respond to this one?

All his fingers (and toes) are otherwise occupied.

angrymotorist17:35 pm 04 Jun 12

MarkS? Not so quick to respond to this one?

Cracks in the wall had to FOIed?

Well, that just about sums up how this government works these days it would seem.

Let me reiterate, cracks in the dam wall had to be FOIed.

Raising eyebrows?

Why?

Do you expect to be informed about every issue at every construction site in the ACT?

If they were cracks likely to lead to any sort of failure, you can bet the engineers would be calling for some very serious remediation works.

They probably didn’t want to make the information public because of exactly the sort of uninformed speculation you’re likely to see on this thread.

justin heywood7:16 pm 04 Jun 12

‘Après moi, le Deluge’

In so many ways, this should be the motto for this lot.

And dumped under the cover of the ACT Budget! It really is a metaphor for the whole Governmet. Is this another F-up we’ll all be paying for?

Gungahlin Al said :

Since when has the lack of an engineering background held some RA readers back from giving engineering assessments? 🙂

It was more a specific invitation.

screaming banshee5:06 pm 04 Jun 12

c_c said :

Having said that, these are not the type of cracks I believe that are inherent to RCC dams, rather, they’ve formed from some issues revealed by the flooding with the abutment structures and from a loss of thermal control of the concrete.

Que?

Gungahlin Al4:55 pm 04 Jun 12

“Any of our readers with engineering backgrounds care to give their assessment?”

Since when has the lack of an engineering background held some RA readers back from giving engineering assessments? 🙂

Does anyone have an emergency response plan for in the case that it gets worse?

If not then…

Holden Caulfield said :

Run for the hills!

+1

Before people panic, it’s important to realise RCC dams from the outset tend to be leaky with cracks until they’re sealed after construction anyway.

Having said that, these are not the type of cracks I believe that are inherent to RCC dams, rather, they’ve formed from some issues revealed by the flooding with the abutment structures and from a loss of thermal control of the concrete.

Sigh…

Just tear it down and start all over again.

chaaa ching ……..
These guys have the loudest cash register in the ACT

wildturkeycanoe4:11 pm 04 Jun 12

Can’t see it from my place!

Buckaroo_Banzai4:10 pm 04 Jun 12

Gaffa tape.

Holden Caulfield3:56 pm 04 Jun 12

Run for the hills!

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