Mersey and the Ship Canal.

[Peter T]

Given that Warrington is a potential flood area, and that the main drainage is the River Mersey and the Manchester Ship Canal, how often to they get dredged to remove the build-up of silt. I know they used to do the canal but don't whether they still do. I have never heard of the Mersey being dredged.

 

If this doesn't happen, are the levels going to rise and increase the risk of flooding?

[Evil Sid]

i think there are problems with dredging the Mersey around Warrington as there are numerous submarine cables running under it.

not sure if they still dredge around the Liverpool end but would think that they do to keep the shipping lanes open.

 

found this link which gives a little detail on this.

http://www.clydeport.co.uk/index.php?site_id=6&page_id=381

 

Every year the Company has to dredge on average 850,000 cubic metres of sand and silt which enters the Canal from the rivers which feed into it. The rivers Irwell, Mersey and Weaver drain a total catchment in the northwest of about 2000sq.km.

 

not sure how old the information is. there is a link to an excel document that gives annual tonnage but it only goes up to 2006.

[LymmParent]

I'm sure this is a Geoff question, but should you dredge a river? Doesn't it upset something or other? Canals are man-made and need dredging to get rid of dead cats, shopping trolleys and Wingy's Woolly Buggers....

[safeway56]

Canals aren't dredged...it would destroy the lining which is called puddling without which there'd be very nasty floods all over the place.

[LymmParent]

Well, what's the dredger that goes up and down every now and then doing? Ruddy great vacuuming thing spitting sand and dead cats and the like. Are there degrees of dredgery? Where's Asp when you really need him?!

[Dizzy]

LP is right and they certainly used to dredge the Bridgewater Canal as we used to watch them doing it. They dredged the Manchester Ship Canal too.

 

Infact Woolston Eyes were/are the deposit grounds for dredgings from the Manchester Ship Canal (MSC).

 

Part of Moore Nature Reserve was built up from the regular dredgings of the River Mersey.

 

And near Frodsham there is another area made up of dredgings from the Manchester Ship Canal... and Peel Holdings (Energy) are planning on putting 21 wind turbines on it After testing of course Peter

[Peter T]

[Dizzy]

[safeway56]

Well, what's the dredger that goes up and down every now and then doing? Ruddy great vacuuming thing spitting sand and dead cats and the like. Are there degrees of dredgery? Where's Asp when you really need him?!

 

You've probably seen the clean up vessel which is based at Barton Aqueduct which collects floating rubbish and other objects such as old bikes and shopping trollies. I had a narrowboat based at Runcorn for a long time and never witnessed any local canals being dredged.

[observer]

Just for interest, does the Mersey have an over-flow pipe into the Man S Canal? I remember when St John's school got flooded, the MSC wasn't full to the brim.

[vic]

Canals are dredged. BW spends ?7m a year dredging.

 

http://www.britishwaterways.net/newsroom/all-press-releases/display/id/1336

 

Here's a dredger and a tub full of dredgings ...

 

http://2.bp.blogspot.com/_YPN2eh4cswU/SK2UChdIqVI/AAAAAAAAAK0/1OZ-rxIwdqI/s1600-h/dredger.JPG

 

http://4.bp.blogspot.com/_YPN2eh4cswU/SK2UBFZYgwI/AAAAAAAAAKc/P_nPeVLa048/s320/BW+dredging.JPG

 

The MSC is the Mersey between Irlam and Rixton. Water level to Latchford locks is same as on Mersey to Woolston Weir. Excess flows both over the weir and through the lock sluices. I can't recall when Newman (?) flooded but presume it was high tide (and the tide was over the Howley Weir). I don't think there's an outlet from the MSC until the Weaver Sluices beyond Runcorn.

[wolfie]

Just for interest, does the Mersey have an over-flow pipe into the Man S Canal? .

 

Eh, wouldn't the overflow go right back into the Mersey?

[observer]

Err yes, but presumably lower down - the level of the Mersey at Kingsway can be higher than the level at the MSC - but Vic's right, a high tide would no doubt compromise matters. So the bottom line appears to be, that now and again the flood plain will flood, so it shouldn't be built on.

[Dizzy]

Not really on topic but no boats have been down the MSC this week... I know that cos it's still frozen with a dusting of snow on the top

[byrdy]

I can't ever remember snow laying on the Ship Canal before,not even in the big freeze in the winter of 1962/3(although the canal was full of oil then so it wouldn't).

[Bick]

wow I remember the dredgers on the Mersey but they stopped them at least 20 years ago....

they were big boats with a massive claw type bucket that picked up the foulest black sludge you could ever wish to see. My 6 year old son would have loved them...

 

they mainly dredged the run off from Chester road to the small locks at the back of Cranbourne avenue opposite the old timber yard.... we used to play under the non swinging bridge there and the river was just as wide as the rest of the mersey.

 

now its probably just all mud certainly not a river anymore

 

makes you feel old when what was a pretty treacherous piece of river is now mainly trees bushes and a mud patch...

 

 

 

and I have recently said "I remember when this were all fields"