The one thing I've not seen mentioned anywhere is whether they have been emptying the reservoir by the normal route (valves draining into canal system) in addition to the much-publicised pumping operation. I presume they have, but it's not (that I've seen) been mentioned.
I'm not sure but doubt the valves rely only the feeder to the canal which is small.
Well its good practice for the RAF lads after all they are more accustomed to blowing dams up rather then mending 'em!..
In message <qicn9s$kmg$ snipped-for-privacy@dont-email.me, at 21:17:49 on Tue, 6 Aug 2019, NY snipped-for-privacy@privacy.invalid remarked:
Exactly. Have they decided not to, or has it just escaped the attention of the civilian press?
In message snipped-for-privacy@outlook.com, at
17:01:15 on Tue, 6 Aug 2019, Robin snipped-for-privacy@outlook.com remarked:
But it's also speculation that those bullet points above are either accurate or exhaustive. We are still in a "fog of war" phase.
So it's down to what the informed commentator above means by "rapid", perhaps.
Well it would beggar belief if they *haven?t* opened the normal drain valves but I imagine that they?re not designed to empty a reservoir quickly. After all, if you have a working spillway why would you need a humongous drain valve?
Of course if your spillway fails then you?re in deep trouble but I guess that?s such a rare event mega drain valves aren?t built into reservoirs as a routine.
Tim
Because the spillway only works when the reservoir is 101% full, and you need to drain them when <100% full.
Well now they have, but tomorrow it might be filling up again, unless they have diverted the source.
The reservoir already has an outlet to feed the canals and probably another ?service drain?. I?m sure that they were using all all available drains before bringing in pumps. Why wouldn?t they?
Tim
A little way up the thread, someone posted a link to an article in which various experts in the field of dams discussed the Whaley Bridge problem. One of them mentioned that the drain valves had been replaced a while ago with ones that were designed to perform a rapid evacuation of the reservoir if needed.
Because spillways don?t allow you to empty the reservoir.
And plenty of spillways don?t allow you to empty the reservoir and you can need to do that quickly with some dams which can end up with a lot of new water in massive downpours.
Duh. I said ?humongous drain valve?. Of course they have to have a draining method of some type, it just doesn?t need to be humongous under normal circumstances.
Tim
operation. I
The canal system isn't built to carry large volumes of water. The spill ways around locks are tiny, they only have to deal with a lock full of water every five minutes or so.
Peak Forest Canal locks are roughly 22 x 2.25 x 4 m call it 200,000 l. At the start the 16 Fire and Rescue service high volume pumps could shift 112,000 l per *minute*. The larger pumps in place now I'd say they are shifting 500,000 l min or more. 2+ locks worth every minute...
The need to bring the level down quickly means pumps, though I wouldn't be surprised if the media haven't noticed or even thought about the canal. But in the big scheme of things the amount of water you could release that way is not much more than a gnats pee in a pint of lager. The brook at the bottom of the spillway drains into the River Goyt.
reservoir
Aye, there to set a maximum level in the reservior.
But when the dam is full or close to full, and a mega downpour is predicted, the normal drain method wont be able to drain it quickly enough.
Rod that's why we have the overflow. Its the bit that failed, hence the problems.
It does mean floods downstream as the full amount of water will be going downstream, but its a reservoir so not a part of a recent flood control scheme.
In message snipped-for-privacy@news.individual.net>, at 16:09:51 on Wed, 7 Aug 2019, Tim+ snipped-for-privacy@gmail.com remarked:
Agreed. I'm more interested in why it's not been reported. Just lack of observation perhaps?
In message <qietka$npe$ snipped-for-privacy@dont-email.me, at 17:17:58 on Wed, 7 Aug 2019, NY snipped-for-privacy@privacy.invalid remarked:
And we got a bit stalled over the meaning of "rapid". They've been pumping for a week now.
In message <qieq2d$ave$ snipped-for-privacy@gioia.aioe.org>, at 16:17:34 on Wed, 7 Aug
2019, Andrew snipped-for-privacy@mybtinternet.com remarked:
It's abut 95% drained, so very unlikely to fill up in a day.
Reportedly that was one of the first things they did.
Throughput? Presumably, those pumps can produce more grunt than gravity.
They appeared to be digging channels to redirect it.
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