On 06/08/2019 21:17, NY wrote:
"Robin" wrote in message
...
Although the question being asked in this thread is "if that's the
case, why also use lots of pumps".

well I don't claim to have any engineering qualifications but it seems
to me a plausible answer is in the public statements:

- the spillway was damaged leading to a risk of catastrophic failure,

- there was a lot of water in the reservoir

- water was still coming in at a high rate (and with the risk of more
rain to come)

so it seemed like a good idea to lower the level faster than would be
possible without the pumps (with the added benefit of being able to
send water to different places and so avoid downstream flooding).

To the best of my recollection and belief, all the above is on the
public record.

But then some prefer speculation.

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.

--
Robin
reply-to address is (intended to be) valid

In article , Martin Brown '''newspam'''@n
ezumi.demon.co.uk scribeth thus
On 06/08/2019 05:51, The Natural Philosopher wrote:
On 05/08/2019 22:38, NY wrote:
"The Natural Philosopher" wrote in message
...
On 05/08/2019 12:30, Cynic wrote:
Hopefully "lessons will be learned" and dam designs include means of
drainage for maintenance or emergency. A bloody big tap at the
bottom?

No lessons will be learnt. Virtue signalling is more important than
actually achieving reliable infrastructure.

Hopefully the company that did the annual safety inspection and
pronounced the dam "absolutely fine" is well insured - because all the
work over the past week will have cost a lot.

It probably WAS absolutely fine until the heavy rain

Maybe. Certainly the heavy rain stressed one edge of the spillway to a
point where it failed catastrophically. There may well have been a
latent fault that allowed water to get behind one of the panels.

I bet you the work hasnt cost even one useless wind turbine yet

I dunno. The flying time of the Chinnooks must be mounting up by now.
£24k an hour of flying time according to defence minister Bob Ainsworth:

https://www.pprune.org/archive/index.php/t-302234.html

And that was about a decade ago - Hansard entry:

https://publications.parliament.uk/p...ext/71126w0001
.htm

Military aircraft operating costs. Apache is nearly double that!


Well its good practice for the RAF lads after all they are more
accustomed to blowing dams up rather then mending 'em!..
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

"tony sayer" wrote in message
...
In article , Martin Brown '''newspam'''@n
ezumi.demon.co.uk scribeth thus
On 06/08/2019 05:51, The Natural Philosopher wrote:
On 05/08/2019 22:38, NY wrote:
"The Natural Philosopher" wrote in message
...
On 05/08/2019 12:30, Cynic wrote:
Hopefully "lessons will be learned" and dam designs include means of
drainage for maintenance or emergency. A bloody big tap at the
bottom?

No lessons will be learnt. Virtue signalling is more important than
actually achieving reliable infrastructure.

Hopefully the company that did the annual safety inspection and
pronounced the dam "absolutely fine" is well insured - because all the
work over the past week will have cost a lot.

It probably WAS absolutely fine until the heavy rain

Maybe. Certainly the heavy rain stressed one edge of the spillway to a
point where it failed catastrophically. There may well have been a
latent fault that allowed water to get behind one of the panels.

I bet you the work hasnt cost even one useless wind turbine yet

I dunno. The flying time of the Chinnooks must be mounting up by now.
£24k an hour of flying time according to defence minister Bob Ainsworth:

https://www.pprune.org/archive/index.php/t-302234.html

And that was about a decade ago - Hansard entry:

https://publications.parliament.uk/p...ext/71126w0001
.htm

Military aircraft operating costs. Apache is nearly double that!


Well its good practice for the RAF lads after all they are more
accustomed to blowing dams up rather then mending 'em!..

They actually deliver stuff using choppers a lot more than they blow up
dams.

In message , at 21:17:49 on Tue, 6 Aug 2019,
NY remarked:

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.

Exactly. Have they decided not to, or has it just escaped the attention
of the civilian press?
--
Roland Perry

In message , at
17:01:15 on Tue, 6 Aug 2019, Robin remarked:

Some rather more than averagely informed comments are at
https://www.sciencemediacentre.org/e...s-that-the-wha
ley-bridge-dam-has-been-damaged/

"Within the last few years new valves have been placed in the dam to
expedite rapid drawdown in emergencies: presumably, this is happening
now."
Although the question being asked in this thread is "if that's the
case, why also use lots of pumps".

well I don't claim to have any engineering qualifications but it seems
to me a plausible answer is in the public statements:

- the spillway was damaged leading to a risk of catastrophic
failure,

- there was a lot of water in the reservoir

- water was still coming in at a high rate (and with the risk of
more rain to come)

so it seemed like a good idea to lower the level faster than would be
possible without the pumps (with the added benefit of being able to
send water to different places and so avoid downstream flooding).

To the best of my recollection and belief, all the above is on the
public record.

But it's also speculation that those bullet points above are either
accurate or exhaustive. We are still in a "fog of war" phase.
But then some prefer speculation.

So it's down to what the informed commentator above means by "rapid",
perhaps.
--
Roland Perry

On Wed, 7 Aug 2019 13:24:44 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:


Well its good practice for the RAF lads after all they are more
accustomed to blowing dams up rather then mending 'em!..

They actually deliver stuff using choppers a lot more than they blow up
dams.

Auto-contradicting senile ASSHOLE!!!! tsk

--
Kerr-Mudd,John addressing senile Rot:
"Auto-contradictor Rod is back! (in the KF)"
MID:

Roland Perry wrote:
In message , at 21:17:49 on Tue, 6 Aug 2019,
NY remarked:

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.

Exactly. Have they decided not to, or has it just escaped the attention
of the civilian press?

Well it would beggar belief if they *havent* opened the normal drain
valves but I imagine that theyre 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 youre in deep trouble but I guess
thats such a rare event mega drain valves arent built into reservoirs as
a routine.

Tim

--
Please don't feed the trolls

In message
,
at 10:07:21 on Wed, 7 Aug 2019, Tim+ remarked:
Roland Perry wrote:
In message , at 21:17:49 on Tue, 6 Aug 2019,
NY remarked:

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.

Exactly. Have they decided not to, or has it just escaped the attention
of the civilian press?

Well it would beggar belief if they *havent* opened the normal drain
valves but I imagine that theyre not designed to empty a reservoir
quickly. After all, if you have a working spillway why would you need a
humongous drain valve?

Because the spillway only works when the reservoir is 101% full, and you
need to drain them when 100% full.

--
Roland Perry

On 07/08/2019 12:36, Roland Perry wrote:
In message
,
at 10:07:21 on Wed, 7 Aug 2019, Tim+ remarked:
Roland Perry wrote:
In message , at 21:17:49 on Tue, 6 Aug 2019,
NY remarked:

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.

Exactly. Have they decided not to, or has it just escaped the attention
of the civilian press?

Well it would beggar belief if they *havent* opened the normal drain
valves but I imagine that theyre not designed to empty a reservoir
quickly. After all, if you have a working spillway why would you need a
humongous drain valve?

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.

Roland Perry wrote:
In message
,
at 10:07:21 on Wed, 7 Aug 2019, Tim+ remarked:
Roland Perry wrote:
In message , at 21:17:49 on Tue, 6 Aug 2019,
NY remarked:

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.

Exactly. Have they decided not to, or has it just escaped the attention
of the civilian press?

Well it would beggar belief if they *havent* opened the normal drain
valves but I imagine that theyre not designed to empty a reservoir
quickly. After all, if you have a working spillway why would you need a
humongous drain valve?

Because the spillway only works when the reservoir is 101% full, and you
need to drain them when 100% full.


The reservoir already has an outlet to feed the canals and probably another
€œservice drain€�. Im sure that they were using all all available drains
before bringing in pumps. Why wouldnt they?

Tim

--
Please don't feed the trolls

"Tim+" wrote in message
...
Roland Perry wrote:
In message , at 21:17:49 on Tue, 6 Aug 2019,
NY remarked:

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.

Exactly. Have they decided not to, or has it just escaped the attention
of the civilian press?

Well it would beggar belief if they *havent* opened the normal drain
valves but I imagine that theyre not designed to empty a reservoir
quickly. After all, if you have a working spillway why would you need a
humongous drain valve?

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.

"Tim+" wrote in message
...
Roland Perry wrote:
In message , at 21:17:49 on Tue, 6 Aug 2019,
NY remarked:

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.

Exactly. Have they decided not to, or has it just escaped the attention
of the civilian press?

Well it would beggar belief if they *havent* opened the normal drain
valves but I imagine that theyre not designed to empty a reservoir
quickly. After all, if you have a working spillway why would you need a
humongous drain valve?

Because spillways dont allow you to empty the reservoir.

And plenty of spillways dont 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.
https://www.youtube.com/watch?v=aX_efvvsyWg

Of course if your spillway fails then youre in deep trouble but I guess
thats such a rare event mega drain valves arent built into reservoirs as
a routine.

On Thu, 8 Aug 2019 06:20:01 +1000, jleikppkywk, better known as cantankerous
trolling senile geezer Rodent Speed, wrote:

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?

Because spillways don¢t allow you to empty the reservoir.

Still not ONE feedback for you in this thread, you senile trolling asshole?
And nobody can say that you don't keep trying and trying...

Maybe it's time for you to change your nym yet again, asshole! BG

--
"Anonymous" to trolling senile Rot Speed:
"You can **** off as you know less than pig **** you sad
little ignorant ****."
MID:

jleikppkywk wrote:


"Tim+" wrote in message
...
Roland Perry wrote:
In message , at 21:17:49 on Tue, 6 Aug 2019,
NY remarked:

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.

Exactly. Have they decided not to, or has it just escaped the attention
of the civilian press?

Well it would beggar belief if they *havent* opened the normal drain
valves but I imagine that theyre not designed to empty a reservoir
quickly. After all, if you have a working spillway why would you need a
humongous drain valve?

Because spillways dont allow you to empty the reservoir.

Duh. I said €œhumongous drain valve€�. Of course they have to have a draining
method of some type, it just doesnt need to be humongous under normal
circumstances.

Tim

On Thu, 8 Aug 2019 06:20:01 +1000, jleikppkywk wrote:

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.

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...

Exactly. Have they decided not to, or has it just escaped the
attention of the civilian press?

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.

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?

Because spillways don t allow you to empty the reservoir.

Aye, there to set a maximum level in the reservior.

--
Cheers
Dave.

"Tim+" wrote in message
...
jleikppkywk wrote:


"Tim+" wrote in message
...
Roland Perry wrote:
In message , at 21:17:49 on Tue, 6 Aug
2019,
NY remarked:

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.

Exactly. Have they decided not to, or has it just escaped the attention
of the civilian press?

Well it would beggar belief if they *havent* opened the normal drain
valves but I imagine that theyre not designed to empty a reservoir
quickly. After all, if you have a working spillway why would you need a
humongous drain valve?

Because spillways dont allow you to empty the reservoir.

Duh. I said €œhumongous drain valve€�. Of course they have to have a
draining
method of some type, it just doesnt need to be humongous under normal
circumstances.

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.

On Thu, 8 Aug 2019 08:41:02 +1000, jleikppkywk, better known as cantankerous
trolling senile geezer Rodent Speed, wrote:


Duh. I said ´humongous drain valve¡. Of course they have to have a
draining
method of some type, it just doesnÿt need to be humongous under normal
circumstances.

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.

Says WHO? YOU, the senile trolling asshole from Oz? LOL

--
Website (from 2007) dedicated to the 85-year-old trolling senile
cretin from Oz:
https://www.pcreview.co.uk/threads/r...d-faq.2973853/

On 07/08/2019 23:41, jleikppkywk wrote:




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
,
at 16:09:51 on Wed, 7 Aug 2019, Tim+ remarked:
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.

Exactly. Have they decided not to, or has it just escaped the attention
of the civilian press?

Well it would beggar belief if they *havent* opened the normal drain
valves but I imagine that theyre not designed to empty a reservoir
quickly. After all, if you have a working spillway why would you need a
humongous drain valve?

Because the spillway only works when the reservoir is 101% full, and you
need to drain them when 100% full.

The reservoir already has an outlet to feed the canals and probably another
€œservice drain€�. Im sure that they were using all all available drains
before bringing in pumps. Why wouldnt they?

Agreed. I'm more interested in why it's not been reported. Just lack of
observation perhaps?
--
Roland Perry

In message , at 17:17:58 on Wed, 7 Aug 2019,
NY remarked:
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.

Exactly. Have they decided not to, or has it just escaped the attention
of the civilian press?

Well it would beggar belief if they *havent* opened the normal drain
valves but I imagine that theyre not designed to empty a reservoir
quickly. After all, if you have a working spillway why would you need a
humongous drain valve?

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.

And we got a bit stalled over the meaning of "rapid". They've been
pumping for a week now.
--
Roland Perry

In message , at 16:17:34 on Wed, 7 Aug
2019, Andrew remarked:

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.

Exactly. Have they decided not to, or has it just escaped the attention
of the civilian press?

Well it would beggar belief if they *havent* opened the normal drain
valves but I imagine that theyre not designed to empty a reservoir
quickly. After all, if you have a working spillway why would you need a
humongous drain valve?
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,

It's abut 95% drained, so very unlikely to fill up in a day.

unless they have diverted the source.

Reportedly that was one of the first things they did.
--
Roland Perry

On 04/08/2019 20:04, Tim+ wrote:
Why not syphons? I mean, pumps use power, quite a lot of it and are
relatively expensive. For a syphon, you just need a suitably sized bit of
pipe.

Throughput? Presumably, those pumps can produce more grunt than gravity.

--
F

On 05/08/2019 12:26, Chris Hogg wrote:
On Mon, 5 Aug 2019 11:25:57 +0100, nightjar wrote:


By building dams in the feeder steams, the water can be pumped away
before it reaches the reservoir.

Yebbut where to?

They appeared to be digging channels to redirect it.

--
F

In article , Roland Perry
writes
In message
,
at 16:09:51 on Wed, 7 Aug 2019, Tim+ remarked:
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.

Exactly. Have they decided not to, or has it just escaped the attention
of the civilian press?

Well it would beggar belief if they *havent* opened the normal drain
valves but I imagine that theyre not designed to empty a reservoir
quickly. After all, if you have a working spillway why would you need a
humongous drain valve?

Because the spillway only works when the reservoir is 101% full, and you
need to drain them when 100% full.

The reservoir already has an outlet to feed the canals and probably another
€œservice drain€�. Im sure that they were using all all available drains
before bringing in pumps. Why wouldnt they?

Agreed. I'm more interested in why it's not been reported. Just lack of
observation perhaps?
Probably. No very visible and not as exciting as fire engines and lots
of pipes and pumps. Also not straightforward to dump loads of water into
the canal system. The pumps were emptying into the river.
--
bert

In message , at 13:10:36 on Fri, 9 Aug 2019,
bert remarked:

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.

Exactly. Have they decided not to, or has it just escaped the attention
of the civilian press?

Well it would beggar belief if they *havent* opened the normal drain
valves but I imagine that theyre not designed to empty a reservoir
quickly. After all, if you have a working spillway why would you need a
humongous drain valve?

Because the spillway only works when the reservoir is 101% full, and you
need to drain them when 100% full.

The reservoir already has an outlet to feed the canals and probably another
€œservice drain€�. Im sure that they were using all all available drains
before bringing in pumps. Why wouldnt they?

Agreed. I'm more interested in why it's not been reported. Just lack
of observation perhaps?

Probably. No very visible and not as exciting as fire engines and lots
of pipes and pumps.

That's gets my vote for the most likely answer.

Also not straightforward to dump loads of water into the canal system.

Although it's incredibly straightforward. One bloke just needs to open a
handful of sluices (to use a generic name).

The pumps were emptying into the river.

And they will have calculated whether there was going to be any
collateral damage downstream. The river doesn't have infinite capacity
any more than the canal.
--
Roland Perry

Roland Perry wrote:
In message , at 13:10:36 on Fri, 9 Aug 2019,
bert remarked:

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.

Exactly. Have they decided not to, or has it just escaped the attention
of the civilian press?



The reservoir already has an outlet to feed the canals and probably another
€œservice drain€�. Im sure that they were using all all available drains
before bringing in pumps. Why wouldnt they?

Agreed. I'm more interested in why it's not been reported. Just lack
of observation perhaps?

Probably. No very visible and not as exciting as fire engines and lots
of pipes and pumps.

That's gets my vote for the most likely answer.

Also not straightforward to dump loads of water into the canal system.

Although it's incredibly straightforward. One bloke just needs to open a
handful of sluices (to use a generic name).


Last week I took a gander at the CART stoppage notices for the Peak Forest
canal , the closure notice wasnt
that informative and just said they were drawing down water in a controlled
manner from the reservoir and that the Peak Forest Canal was closed as was
the Bosley flight of Locks on the Macclesfield Canal.
The latter joins the Peak Forest just above the Marple flight of the Peak
Forest so may suggest that the
CART staff had closed the Macclesfield Locks so no additional flow from
there would hinder what had to be got away from down the Peak Forest from
Whaley Bridge and down through the Marple flight.

Interesting when they started to rescind the navigation restrictions on
the 7th they referred to removing stop planks from bridges on the Peak
Forest Canal.

Putting stop planks in a canal you want to drain down quickly seems counter
intuitive but maybe it was an insurance in case the dam did breach in
attempt to break up any possible large discharge from that.
So none the wiser really from the stoppage notices.
Perhaps only some stop planks were in permitting some flow but allowing
staff the possibility of quickly inserting the last to full height quickly
if required.

Will have to keep an eye on one of the waterway periodicals over the next
issues to see if details come out.

GH

Marland wrote:
Roland Perry wrote:
In message , at 13:10:36 on Fri, 9 Aug 2019,


Also not straightforward to dump loads of water into the canal system.

Although it's incredibly straightforward. One bloke just needs to open a
handful of sluices (to use a generic name).


Last week I took a gander at the CART stoppage notices for the Peak Forest
canal , the closure notice wasnt
that informative and just said they were drawing down water in a controlled
manner from the reservoir and that the Peak Forest Canal was closed as was
the Bosley flight of Locks on the Macclesfield Canal.
The latter joins the Peak Forest just above the Marple flight of the Peak
Forest so may suggest that the
CART staff had closed the Macclesfield Locks so no additional flow from
there would hinder what had to be got away from down the Peak Forest from
Whaley Bridge and down through the Marple flight.

Silly me ,my Canal geography memory is slipping . The Bosley flight goes
down from the area not feeds it.

Still that means that closing the Bosley flight to navigation would allow
some discharge down the Macclesfield
and into the Trent and Mersey and onwards.

GH

In article , Roland Perry
writes
In message , at 13:10:36 on Fri, 9 Aug 2019,
bert remarked:

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.

Exactly. Have they decided not to, or has it just escaped the attention
of the civilian press?

Well it would beggar belief if they *havent* opened the normal drain
valves but I imagine that theyre not designed to empty a reservoir
quickly. After all, if you have a working spillway why would you need a
humongous drain valve?

Because the spillway only works when the reservoir is 101% full, and you
need to drain them when 100% full.

The reservoir already has an outlet to feed the canals and probably another
€œservice drain€�. Im sure that they were using all all
available drains
before bringing in pumps. Why wouldnt they?

Agreed. I'm more interested in why it's not been reported. Just lack
of observation perhaps?

Probably. No very visible and not as exciting as fire engines and lots
of pipes and pumps.

That's gets my vote for the most likely answer.

Also not straightforward to dump loads of water into the canal system.

Although it's incredibly straightforward. One bloke just needs to open
a handful of sluices (to use a generic name).

The pumps were emptying into the river.

And they will have calculated whether there was going to be any
collateral damage downstream. The river doesn't have infinite capacity
any more than the canal.
No but the river's capacity is much much greater.
--
bert