Narrows on the Selby Canal

[Grebe]

Yesterday we were at West Haddlesey on the Selby Canal doing some photography and a bit of walking. We walked up to the narrows that look like an aqueduct but there was no watercourse.

 

Having looked at maps and images along the canal there are similar structures. Does anyone know what they were originally bulit for?

[Naughty Cal]

Do you mean where the old swing and lift bridges were?

[Grebe]

Not sure what they were for. Swing bridges would seem pointless as there are other fixed bridges and the remaining abuttments/narrows are very high and substancial. They also have pools behind them.

 

We are now thinking they are inverted syphons that were used to get canal over existing drains/ditches at the time of construction. Normal practice would have been to put the canal on an embankment with proper culverts. Perhaps the needs of the flood plain, River Aire levels etc. required a more radical approach.

[Lady Muck]

I wondered what they are too, bit of local interest for me, my brother lives in West Haddlesey and my family are from Knottingley.

[mayalld]

Yesterday we were at West Haddlesey on the Selby Canal doing some photography and a bit of walking. We walked up to the narrows that look like an aqueduct but there was no watercourse.

 

Having looked at maps and images along the canal there are similar structures. Does anyone know what they were originally bulit for?

 

Pictures please!

[Naughty Cal]

[RLWP]

Thanks Phylis. That's surely and inverted syphon. There's a drainage ditch connected to each side pond

 

Richard

[Naughty Cal]

From the water they certainly look like old stone built bridge abutments. You dont appreciate the ditches from water level.

[Iain_S]

My understanding of these structures is that they are needed to equalise the ground water pressure on each side of the canal, which is built through sandy soil with impervious stuff underneath. They are indeed inverted syphons.

 

Iain

[Grebe]

Phylis, thanks for doing the picture.

 

RLWP and Iain_s, thanks for your comments confirming our suspicions. We had not considered the pressure equalization point before.

 

 

Regards

 

Mal

[pearley]

My very old guide book describes them as syphons.

[jez1954]

My very old guide book describes them as syphons.

Sorry for being stupid - but what's a syphon in this context and what was its/their purpose?

ps. Non technical member.....DIY stands for destroy it yourself!!

 

Jez

[Paul Evans]

Sorry for being stupid - but what's a syphon in this context and what was its/their purpose?

ps. Non technical member.....DIY stands for destroy it yourself!!

 

Jez

 

From Wikipedia:

 

"An inverted siphon is not a siphon but a term applied to pipes that must dip below an obstruction to form a "U" shaped flow path. Inverted siphons are commonly called traps for their function in preventing smelly sewer gases from coming back out of drains and sometimes making dense objects like rings and electronic components retrievable after falling into a drain. Liquid flowing in one end simply forces liquid up and out the other end, but solids like sand will accumulate. This is especially important in sewage systems or culverts which must be routed under rivers or other deep obstructions where the better term is "depressed sewer". Large inverted siphons are used to convey water being carried in canals or flumes across valleys, for irrigation or gold mining."

Edited September 7, 2010 by Paul Evans

[Paul Evans]

I knew I had a picture of a syphon somewhere:

 

 

This is from "Welland and the Welland Canal - The Canal By-Pass Project" by John N Jackson published in 1975 by Mika Publishing Co and, in the book, attributed to Welland Tribune.

 

For those looking to visit the Welland Canal, you'll need to get your boat to Canada because it is part of the St Lawrence Seaway and joins Lake Ontario to Lake Erie, by-passing Niagara Falls.

 

Admin Team - I managed to put 2 pictures in the gallery one acknowledging Thw Welland Tribune and the other not. Can you delete the wrongly attributed version please?

Edited September 7, 2010 by Paul Evans

[jez1954]

From Wikipedia:

 

"An inverted siphon is not a siphon but a term applied to pipes that must dip below an obstruction to form a "U" shaped flow path. Inverted siphons are commonly called traps for their function in preventing smelly sewer gases from coming back out of drains and sometimes making dense objects like rings and electronic components retrievable after falling into a drain. Liquid flowing in one end simply forces liquid up and out the other end, but solids like sand will accumulate. This is especially important in sewage systems or culverts which must be routed under rivers or other deep obstructions where the better term is "depressed sewer". Large inverted siphons are used to convey water being carried in canals or flumes across valleys, for irrigation or gold mining."

 

Thank you - all is now clear.

 

Jez

[the grinch]

I knew I had a picture of a syphon somewhere:

 

 

This is from "Welland and the Welland Canal - The Canal By-Pass Project" by John N Jackson published in 1975 by Mika Publishing Co and, in the book, attributed to Welland Tribune.

 

For those looking to visit the Welland Canal, you'll need to get your boat to Canada because it is part of the St Lawrence Seaway and joins Lake Ontario to Lake Erie, by-passing Niagara Falls.

 

Admin Team - I managed to put 2 pictures in the gallery one acknowledging Thw Welland Tribune and the other not. Can you delete the wrongly attributed version please?

 

why go that far?? there is one on the basingstoke canal at Odiham!!

[DandV]

I am just interested as to how are inverted siphons prevented from silting up?

 

Cheers Don

[Paul Evans]

I am just interested as to how are inverted siphons prevented from silting up?

 

Cheers Don

 

Google Books has a "copy" of Sewers: replacement and new construction By Geoffrey F. Read that includes a (very technical) description of the design of inverted syphons. I just put inverted syphon silting into a Google search but to save you doing that here's The Link. I assume that similar considerations apply to syphons under canals carrying drainage water.

[the grinch]

I am just interested as to how are inverted siphons prevented from silting up?

 

Cheers Don

 

the turbulance created stirs everything up and that stops any sediment from settling the biggest problem from what i have seen is large items like logs and trees that get lodged as their bouyancy prevents them from passing through left for too long can cause them to block