Old Cotter Dam hears the mermaids singing

54-11 said :

Duffbowl said :

c_c™ said :

bundah said :

Solidarity said :

What was wrong with the old one? (i’m genuinely curious)

Nothing…

If you don’t know what you’re talking about, don’t post.

Bloody hell, if we make that a condition of posting comment, this will rapidly become a very quiet site.

Agreed, what’s with all the aggro? Jeez, it’s only a bloody dam.

Yeah, there’s a surprising amount of heat being generated over this topic. Energy that would be better directed at cyclists, motorists, or the local politicians I reckon. 🙂

54-11 said :

Agreed, what’s with all the aggro? Jeez, it’s only a bloody dam.

There’s more than enough material in the public domain that there’s no excuse, that’s why.

4 years of construction and all the discussion during that time, the better part of 15 years of planning. They looked at more than 30 different options, from entirely new dams, to fuse gates and wall extensions to increase capacity of existing dams, to virtual dams and water recycling.

This is the option they arrived at.

I’m willing to bet the vast majority of the naysayers aren’t familiar with the alternatives explored, or the back story of the existing dam.

The capacity for Canberrans to whinge is astonishing. What’s that I hear? Yes, enough about the Dam, let’s slag off the new airport too.

54-11 said :

Agreed, what’s with all the aggro? Jeez, it’s only a bloody dam.

Only a bloody dam?

It’s an eebil socialistic commie Labor plot to waste the hard-earned dollars of the good burghers of Canberra whose money should be entirely theirs to spend as they please. It’s been put over on us by the greenie global warming liars who tell us there’ll be less water because we haven’t built trams and wind farms when everyone can see that it’s been raining for the last few days and it’s been chilly today!

Understand?

Duffbowl said :

c_c™ said :

bundah said :

Solidarity said :

What was wrong with the old one? (i’m genuinely curious)

Nothing…

If you don’t know what you’re talking about, don’t post.

Bloody hell, if we make that a condition of posting comment, this will rapidly become a very quiet site.

Agreed, what’s with all the aggro? Jeez, it’s only a bloody dam.

patrick_keogh said :

gooterz said :

Is this a metaphor for self government?

Do you mean “Small first steps, moving towards broad capacity on a firm footing?”

More like going under to be stored under 70 odd gigalitres

c_c™ said :

bundah said :

Solidarity said :

What was wrong with the old one? (i’m genuinely curious)

Nothing…

If you don’t know what you’re talking about, don’t post.

Bloody hell, if we make that a condition of posting comment, this will rapidly become a very quiet site.

gooterz said :

Is this a metaphor for self government?

Do you mean “Small first steps, moving towards broad capacity on a firm footing?”

Keijidosha said :

c_c™ said :

For all the bleating about the new dam being expensive and delayed, in context, I think history will prove it a good project that corrects the mistake that was the original dam.

The new Cotter Dam continues the worst legacy of the old dam – being built in a location that requires pumping to supply Canberra. So not only did it cost a mint to build, the ongoing costs just to access the water are steep.

I dare you to drink from the Molonglo River for a week. If you are still well enough to converse after that, try convincing Canberrans to dam up somewhere west of the lake. Got any good catchment options? It’s only Queanbeyan you’d be putting underwater and wow, what an impressively large and expensive dam it would be! Googong does not have enough capacity for supply or they wouldn’t have built the link to the Murrumbidgee either. You do not realise that it’d still have to be pumped in from there anyway. If you wish, and have access to a river, build your own dam in the backyard and fetch water with a bucket to save on pumping costs.

Is this a metaphor for self government?

The new Cotter Dam continues the worst legacy of the old dam – being built in a location that requires pumping to supply Canberra. So not only did it cost a mint to build, the ongoing costs just to access the water are steep.

Now you see, this is the stupid uneducated comments that people who do understand how a utility network should be designed have to put up with on a day to day basis.
I trust you are on some sort of committee throwing in your opinion,making decisions on matters that you clearly have no idea about, whilst ensuring everyone listens when you speak but go to ground and start pointing fingers if it does not pan out how you thought?
Why not try politics 1/2 way I there now!

kakosi said :

I remember the Cotter Dam wasn’t used for many years because the water quality had deteriorated in the source river. It got brought back on line when we had those few years of drought. I’m wondering however if anyone’s questioned whether the original reason for stopping the use of water from that supply is still valid? Is the water quality still dubious compared to the other sources?

There was never a deterioration in the source river, Corin, Bendora and Cotter are all on the Cotter River where 93% of Canberra’s water comes from, and the Cotter Dam is fed from overflow from Bendora and in turn, Corin. The issues with water quality were specific to the Cotter Reservoir, which being so small has silted up basically. With so little capacity and the expense of using it, they shut it down until 05.

I remember the Cotter Dam wasn’t used for many years because the water quality had deteriorated in the source river. It got brought back on line when we had those few years of drought. I’m wondering however if anyone’s questioned whether the original reason for stopping the use of water from that supply is still valid? Is the water quality still dubious compared to the other sources?

poetix said :

I do not think they will sing to me.

I had my white flannel trousers all ready, but couldn’t find the beach.

@ c_c

So harsh now if i’d known that dams gave you a hard on i would’ve opened the floodgates 🙂

c_c™ said :

bundah said :

Behind the door when they were handing out humour?

Very lame attempt at humour.

Keijidosha said :

c_c™ said :

Pure ignorance.

Ignorance of what exactly?

Ignorance because you obviously haven’t gone any further than Canberra Times headlines, or else you would know the detailed studies behind the decisions and wouldn’t dismiss the new dam so flippantly.

There’s three catchments that have always been identified for the ACT: Cotter, Queanbeyan, South ACT (Murrumbidgee, Nass, etc)

Cotter is very large, has the best raw water quality, and has existing supply infrastructure (bulk mains, treatment, pumping, etc)

Queanbeyan is larger, but there’s a demonstrated rain shadow, agricultural use demands higher level of treatment and the water has to be pumped.

South ACT potentially offered the greatest potential to increase supply, but would have required extensive new infrastructure, raw water quality would have been poor and required extensive treatment, and the infrastructure and environmental aspects were always problematic.

The enlarged Cotter Dam greatly increases storages and sources high quality raw inflows. It uses existing infrastructure. It replaces an ageing dam and being at the end of the chain of dams, offers some redundancy as Corin and Bendora age (both of which have already had structural issues identified).

Bendora and Corin remain the primary water storages from which most water will be drawn even after the new dam is commissioned, and Googong remains the main secondary storage.

The new Cotter Dam will only be drawn on when storages or other circumstances demand it as a last resort. It has a design life far in excess of the Tennant Dam with far lower environmental and infrastructure issues than Tennant.

So you have a project that kept upfront costs competitive with other options and will add little if anything to ongoing supply costs.

🙂 Excellent post. Thanks!

MelonHead said :

Didn’t the original dam/pumps use a Pelton wheel pump? Surely that was a good idea at the time.

Close, the Pelton Wheel was part of one of the failed experiments with hydro-electricty generation on the Cotter. It was built opposite the Pumping station, but due to design issues and finally the dodgy location they chose, was destroyed very quickly. They found it decades later in a wreck and put it in the Pumping Station as a relic.

Solidarity said :

What was wrong with the old one? (i’m genuinely curious)

It’s a genuinely long and fascinating list, but here’s a brief run down:

1. It should never have been built
Experts including Corin foresaw a larger, stronger dam higher in the catchment as a better long term option. Elevation would have allowed gravity fed water, and hydro-electric generation could have powered Canberra for a time (into the 50s as it turns out with population growth). Instead, they built a dam lower down, far too small for the catchment, and which required pumping which massively increased abstraction costs, not to mention leading to knock on effects to Canberra’s other infrastructure.

2. Pumping Station was a mistake
Wasn’t built correctly, a maintenance nightmare, caused blackouts and almost failed completely a few times. Very expensive to run.

3. Dam design and construction problems
Dam was designed to be 30m but wasn’t built to full height originally. They didn’t build a gallery nor retain accurate records of how it was built. So it really was a mystery what exactly the dam was by the time the 50s came around and Canberra began to grow. They didn’t dare raise it to full height in the end such were the fears about it. There were deficiencies in construction, the concrete used was well below standard, the calculation on lift forces mistaken, fears they had built the bottom totally flat, it goes on. Add the very frequent overtopping because they miscalculated the size of the catchment that the dam wasn’t design for, not to mention they made the dam to wide for the down stream flow and it’s remarkable how well it held up. The upgrades in the 90s to literally tie the dam down were essential. I remember when the opened the dam after those upgrades, you still see little, mysterious trickles coming out of the 1916 era concrete lower down.

4. Hydro-electric stuff ups
They didn’t go with a higher dam in the catchment until the 60s, but the idea of hydro-electric power stuck, so they tried a few times to do it on the cheap with the Cotter Dam. Never worked. The river side one fell over and was eventually lost. Another attempt with a plant built into the dam wall itself was constructed in the 50s but never used. My understanding is they filled it in eventually, but you could still see a clue on the left side of the wall. They have since added a small generator to the Stromlo plant but it’s far short of the original 1909-1912 ideas people had.

bundah said :

Behind the door when they were handing out humour?

Very lame attempt at humour.

Keijidosha said :

c_c™ said :

Pure ignorance.

Ignorance of what exactly?

Ignorance because you obviously haven’t gone any further than Canberra Times headlines, or else you would know the detailed studies behind the decisions and wouldn’t dismiss the new dam so flippantly.

There’s three catchments that have always been identified for the ACT: Cotter, Queanbeyan, South ACT (Murrumbidgee, Nass, etc)

Cotter is very large, has the best raw water quality, and has existing supply infrastructure (bulk mains, treatment, pumping, etc)

Queanbeyan is larger, but there’s a demonstrated rain shadow, agricultural use demands higher level of treatment and the water has to be pumped.

South ACT potentially offered the greatest potential to increase supply, but would have required extensive new infrastructure, raw water quality would have been poor and required extensive treatment, and the infrastructure and environmental aspects were always problematic.

The enlarged Cotter Dam greatly increases storages and sources high quality raw inflows. It uses existing infrastructure. It replaces an ageing dam and being at the end of the chain of dams, offers some redundancy as Corin and Bendora age (both of which have already had structural issues identified).

Bendora and Corin remain the primary water storages from which most water will be drawn even after the new dam is commissioned, and Googong remains the main secondary storage.

The new Cotter Dam will only be drawn on when storages or other circumstances demand it as a last resort. It has a design life far in excess of the Tennant Dam with far lower environmental and infrastructure issues than Tennant.

So you have a project that kept upfront costs competitive with other options and will add little if anything to ongoing supply costs.

c_c™ said :

bundah said :

Solidarity said :

What was wrong with the old one? (i’m genuinely curious)

Nothing…

If you don’t know what you’re talking about, don’t post.

Behind the door when they were handing out humour?

c_c™ said :

Pure ignorance.

Ignorance of what exactly?

Didn’t the original dam/pumps use a Pelton wheel pump? Surely that was a good idea at the time.

Keijidosha said :

The new Cotter Dam continues the worst legacy of the old dam – being built in a location that requires pumping to supply Canberra.

But that’s where the catchment is and the consumers are where they are.

It’d be nice to be spoiled for choice but I think the idea is that we’ll take any and every catchment we can get at this stage. We only need to pump it if we need it.

I do not think they will sing to me.

Keijidosha said :

c_c™ said :

For all the bleating about the new dam being expensive and delayed, in context, I think history will prove it a good project that corrects the mistake that was the original dam.

The new Cotter Dam continues the worst legacy of the old dam – being built in a location that requires pumping to supply Canberra. So not only did it cost a mint to build, the ongoing costs just to access the water are steep.

Pure ignorance.

c_c™ said :

For all the bleating about the new dam being expensive and delayed, in context, I think history will prove it a good project that corrects the mistake that was the original dam.

The new Cotter Dam continues the worst legacy of the old dam – being built in a location that requires pumping to supply Canberra. So not only did it cost a mint to build, the ongoing costs just to access the water are steep.

bundah said :

Solidarity said :

What was wrong with the old one? (i’m genuinely curious)

Nothing…

If you don’t know what you’re talking about, don’t post.

johnboy said :

it was about a third of the size needed?

That’s the least of it.

Solidarity said :

What was wrong with the old one? (i’m genuinely curious)

Nothing except it’s 2013 and we’re much thirstier these days,besides it’s better to have more than less!

http://www.actewagl.com.au/Environment/Water-statistics-and-weather/Dam-levels.aspx

So when will this be updated to reflect the new capacity?

What was wrong with the old one? (i’m genuinely curious)

What is it about people who write media releases, they’re invariably incompetent.

It wasn’t ‘built in 1915’, even if that year were significant it’s the wrong language. It was built 1912-1916, and the release should read ‘completed in 1916’.

As sad as it is to see the old dam go under, it’s interesting to consider that it was probably the biggest public works mistake in ACT history. Everything about it was flawed, and yet it did a decent job for decades and still stands over a century later. For all the bleating about the new dam being expensive and delayed, in context, I think history will prove it a good project that corrects the mistake that was the original dam.