Canal drainage Berkhamsted

[Kalapattar]

Can anyone explain why the canal frequently drains in Berkhamsted area? No water in Tring reservoir? Broken pumping station? Ta!

[alan_fincher]

41 minutes ago, Kalapattar said:

Can anyone explain why the canal frequently drains in Berkhamsted area? No water in Tring reservoir? Broken pumping station? Ta!

Local youth with too much time on their hands that have found a windlass some boater has failed to pick up when they worked through a lock.

 

(Possibly !)

 

Berko doesn't feel a strong contender in the vandalism sakes, but it is not that many years ago that AV locks were fitted to most of the locks in this town- something I don't recall anywhere else on the Grand Union mainline between Brentford and Birmingham

[ditchcrawler]

1 minute ago, alan_fincher said:

Local youth with too much time on their hands that have found a windlass some boater has failed to pick up when they worked through a lock.

 

(Possibly !)

 

Berko doesn't feel a strong contender in the vandalism sakes, but it is not that many years ago that AV locks were fitted to most of the locks in this town- something I don't recall anywhere else on the Grand Union mainline between Brentford and Birmingham

I thought it was an area where boaters left the exit gates open

[Tonka]

8 minutes ago, alan_fincher said:

Local youth with too much time on their hands that have found a windlass some boater has failed to pick up when they worked through a lock.

 

(Possibly !)

 

Berko doesn't feel a strong contender in the vandalism sakes, but it is not that many years ago that AV locks were fitted to most of the locks in this town- something I don't recall anywhere else on the Grand Union mainline between Brentford and Birmingham

The swimming pool was regularly getting vandalised when it was there in the park.

[matty40s]

1 hour ago, Kalapattar said:

Can anyone explain why the canal frequently drains in Berkhamsted area? No water in Tring reservoir? Broken pumping station? Ta!

Tring Resovoir should new be topped up again, the chalk was dry this summer but should be back to fairly normal groundwater levels now.

Far more likely to be kids, and lazy boaters not shutting gates.

Edited January 13, 2023 by matty40s

[alan_fincher]

32 minutes ago, ditchcrawler said:

I thought it was an area where boaters left the exit gates open

 

20 minutes ago, matty40s said:

...and lazy boaters not shutting gates.

 

There are a lot of "leave empty, with a paddle left up" locks in this town, or very close by to it...

 

Obviously for these, if the top gates are not pretty watertight, with ground and (if present) gate paddles are not fully down, then there is not a second line of defence offered by the bottom gates.

 

Not only that, even if everybody does exactly as CRT wish, any pound that is above a "leave empty" lock potentially has extra water wasted from it where it is necessary for a "downhill" boat to fill it, to replace water lost by the "leave empty" instruction.

[Tonka]

5 minutes ago, alan_fincher said:

 

 

There are a lot of "leave empty, with a paddle left up" locks in this town, or very close by to it...

 

Obviously for these, if the top gates are not pretty watertight, with ground and (if present) gate paddles are not fully down, then there is not a second line of defence offered by the bottom gates.

 

Not only that, even if everybody does exactly as CRT wish, any pound that is above a "leave empty" lock potentially has extra water wasted from it where it is necessary for a "downhill" boat to fill it, to replace water lost by the "leave empty" instruction.

The 2 locks by the gas works were always bad. That is why Sammy Horne used to check them every morning on his way to turn the pump on to bring spring water up.

[Kalapattar]

Ok, thanks for your replies!

[David Mack]

2 hours ago, matty40s said:

Tring Resovoir should new be topped up again, the chalk was dry this summer but should be back to fairly normal groundwater levels now.

According to CRT's December Reservoir Watch, the GU South group of reservoirs, which comprises Startops End, Wilstone, Marsworth and Tringford reservoirs, was 47.7% full, only 2.2% up on the November figure. While this is better than the 2011 low of 32% at the same time of year, its doesn't look too good for this summer's GU boating unless we have a lot of rain in the next couple of months.

[matty40s]

Weve had an awful lot of rain since then, plus snow melt.

[BEngo]

7 hours ago, matty40s said:

Tring Resovoir should new be topped up again, the chalk was dry this summer but should be back to fairly normal groundwater levels now.

 

It is not so much the level of the reservoirs that is important as the level of the water table in the chalk.  If that is low the reservoirs  mainly serve to put water into the chalk since the Tring summit is not fully lined.

Water can though be pumped out of the chalk and  into the cut at Cowroast and at Northchurch.

 

4 hours ago, David Mack said:

According to CRT's December Reservoir Watch, the GU South group of reservoirs, which comprises Startops End, Wilstone, Marsworth and Tringford reservoirs, was 47.7% full, only 2.2% up on the November figure. While this is better than the 2011 low of 32% at the same time of year, its doesn't look too good for this summer's GU boating unless we have a lot of rain in the next couple of months.

 Remembering that the CRT December report  figure was actually recorded in mid-November, so it is well behind reality.  As Matty said, there has been a lot of rain/snow melt since then and a good proportion  of  the reservoir feeders benefit from run-off from the built up areas of Tring.  The railway cutting is also partly drained into the summit ( and partly into the canal below lock 37)  and, subject as above   to the chalk water table, the canal summit benefits accordingly.

 

Nà

[Captain Pegg]

29 minutes ago, BEngo said:

It is not so much the level of the reservoirs that is important as the level of the water table in the chalk.  If that is low the reservoirs  mainly serve to put water into the chalk since the Tring summit is not fully lined.

Water can though be pumped out of the chalk and  into the cut at Cowroast and at Northchurch.

 

 Remembering that the CRT December report  figure was actually recorded in mid-November, so it is well behind reality.  As Matty said, there has been a lot of rain/snow melt since then and a good proportion  of  the reservoir feeders benefit from run-off from the built up areas of Tring.  The railway cutting is also partly drained into the summit ( and partly into the canal below lock 37)  and, subject as above   to the chalk water table, the canal summit benefits accordingly.

 

Nà

 

Lock 37 is the lower of "Peter's Two" I believe? Is there a drainage tunnel that runs from the south end of Tring railway cutting to the canal, and which would explain why there is something that looks like a tunnel ventilation shaft in the hill behind the lock cottage at these locks?

 

[alan_fincher]

9 hours ago, BEngo said:

Water can though be pumped out of the chalk and  into the cut at Cowroast and at Northchurch.

 

There is, however, a fixed limit on the total volume of water that CRT are allowed to extract using the Cowroast and Northchurch pumps.

 

When things get difficult the limit can be reached so extraction has to stop, even though more water is desperately needed.

[David Mack]

9 hours ago, BEngo said:

Remembering that the CRT December report  figure was actually recorded in mid-November, so it is well behind reality

"Reservoir data presented is from the week ending Monday 12 December unless stated along with data from the nearest comparable date in October and November."

[BEngo]

10 hours ago, Captain Pegg said:

 

Lock 37 is the lower of "Peter's Two" I believe? Is there a drainage tunnel that runs from the south end of Tring railway cutting to the canal, and which would explain why there is something that looks like a tunnel ventilation shaft in the hill behind the lock cottage at these locks?

 

There is a positive network of drainage tunnels, pumping culverts and reservoir feeders between the bottom of lk 37, Marsworth Top (Bulbourne), the Startopsend   reservoirs, Wilstone reservoirs, Wendover arm  and the Tringford pumping station.   Alan Faulkner covered some of it in his book on the Grand Junction.  Gavin from BW was THE man for explaining it all  but he's gone now.  I think the local CRT team understand the pumping parts,and the reservoirs but probably not the full extent.

 

The "ventilation shaft"  in the middle of a field on the offside near lock 37 (bottom of Peter's Two)  is part of the North Railway feeder.  The water enters on the sharp inside turn between Peter's Two and DDBC.  There was damned great bush there last time we passed so you could not see the stream.

 

N

 

 

[GUMPY]

4 hours ago, BEngo said:

Gavin from BW was THE man for explaining it all  but he's gone now.  I think the local CRT team understand the pumping parts,and the reservoirs but probably not the full extent.

His talks on the system were a mine of information

[magnetman]

I think there might be one or two locks in berko which could do with windows in the sluices. It is a long time since I was there but I seem to think there were no overspills. Obviously windows can help with this but you do need a reliable feed from further up. 

 

 

Stockers lock in Ricky had windows and probably still does otherwise the pound would go low because Springwell lock is deeper. 

 

Another lock which needed windows quite badly was Sarah's top lock in Watford. This would have helped with the short pound there and there was plenty of water for it. 

I don't think the structure of modern composite paddles can deal with having a window cut in them which is a definite disadvantage. 

 

Aynho and the other weir lock on the Oxford are two other obvious examples of paddles with windows. 

Edited January 14, 2023 by magnetman