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Building On River Bank! Help!

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#1 katrinalucy


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Posted 08 March 2016 - 09:20 AM

Hi all

I am sorry if this is not entirely relevant to the site but I can't imagine anywhere is this specific! I am a year 1 Architectural Technology student. We've been given some sites for a hypothetical project and the one I want to use is a river bed that is currently unsupported and boggy - the river level varies from about 0.75 to - 1.65m. We're not building a house - just a small structure for people rest in or on.

Picture at: http://www.dropbox.c...stance.JPG?dl=0

Does anyone know if you can reinforce a riverbed, which is pretty much a muddy build-up at the side of the river, which will sometime get flooded? I appreciate you would need more information but just roughly any ideas I could look into further?

Alternatively, I was thinking of mooring something to it but with such varying water levels this may also be a nightmare!

Any thoughts whatsoever would be really helpful as I am stumped!

Kind regards

Edited by joiner, 08 March 2016 - 04:55 PM.
Added "know"

#2 ProDave


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Posted 08 March 2016 - 09:39 AM

I think your best bet would be to build something on piles driven into the ground. It would have to be high enough to be above the flood level.

Don't forget that to do anything to a river bed you need permission from the Environment Agency (SEPA in Scotland)

#3 recoveringacademic


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Posted 08 March 2016 - 09:43 AM

And why not make the small structure on which people can rest a pontoon.... which floats up and down those piles.
Exactly like you see in many tidal marinas around the coast..

Good luck

#4 ProDave


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Posted 08 March 2016 - 09:50 AM

The only issue with that. if it's on the bank, is ensuring it sits level when the water is at it's lowest (and the pontoon may not actually be floating then)

This is a typical pontoon in a harbour (just happens to be where I keep my boat, but they have re jigged the pontoons a bit since the photo was taken) They sit level there when the tide is out because periodically the harbour is dredged to leave a flat, sandy bottom.
Attached File  pontoon.jpg   66.33K   5 downloads

#5 joe90


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Posted 08 March 2016 - 10:03 AM

Hi, you mention actually building on a river bed, well seaside piers work quite well on piles and you would need to ensure you don't restrict the river flow beneath it. The title says riverside bank so I guess piles below the bed level would still be the best option IMHO.

Edited by joe90, 08 March 2016 - 10:06 AM.

#6 lakelandfolk



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Posted 08 March 2016 - 11:46 AM

Hi, your pic looks exactly like our house garden wall, (ie a 2 - 3 metre river bank alongside our garden wall) we have riparian rights to the centre of the beck so maintain the bank to prevent damage to the wall. You will almost certainly require permission from the EA to undertake any work on the river and they will not be keen on anything that might interfere with the water flow especially in flood conditions. . The EA prefer bank erosion mitigation to be soft/eco friendly and were happy for us to install willow spiling to support the bank and avoid possible under wash of the wall foundations.
We are in the "flood capital of the North", Cockermouth but our spiling has stood up to 2 of the worst floods in over 100 years and still in good shape. It's a rewarding and therapeutic task to do, only down side is that you will need a considerable amount of back fill to level your bank side. Our spiling is about 1 metre high, but it can be terraced with a second row behind/above the first if necessary. It establishes very quickly and is incredibly resilient to the high, fast flowing water.

#7 jsharris


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Posted 08 March 2016 - 12:31 PM

Piles driven into riverbeds cause very little in the way of disturbance to flow and can be very long lived ("piled" raised timber walkways across bogs have been found to be in a good state of preservation after a few thousand years).

There are lots of different pile technologies, but helical screw piles have minimal ecological impact and can last a long time (some Victorian seaside piers are supported on cast iron screw piles).

Piles like this would be the cheapest and least intrusive method of providing a foundation for a structure. The normal method would be to drive them to depth then join the tops with a ring beam (concrete, steel or timber) to support the structure.

Edited by jsharris, 08 March 2016 - 12:31 PM.

#8 SteamyTea


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Posted 08 March 2016 - 01:33 PM

The Lifeboat Station at Sennen Cove was recently redone with some huge piles.
They seem to cope with extreme 'flooding'.

More to the point, as far as I am concerned, is 'why build in the floodplain?'.
It may be technically possible, but is it really practical, or morally correct to do so.

Edited by SteamyTea, 08 March 2016 - 01:33 PM.

#9 tennentslager


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Posted 08 March 2016 - 03:47 PM

link to a site about building a crannog...

#10 joiner


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Posted 08 March 2016 - 04:59 PM

:) Nick, it's a hypothetical student project. ;)

And Katrina, you certainly know how to get this hairy lot off their backsides and responding. No idea how you've managed that, but thank you for not opening your post with: "Well, hello boys". :rolleyes:

Oh, and welcome. B)

Edited by joiner, 08 March 2016 - 05:00 PM.

#11 ferdinand


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Posted 09 March 2016 - 09:01 AM

Piling is probably better than doing things to the river bed because it causes less disruption to the local environment, and to the water flow which is a hot topic.

If you have a bunny-hugging lecturer they might appreciate some sort of electricity generating device underneath, perhaps even with a storage system for low power lights etc.

Consider your species of wood carefully. I might suggest Greenheart, which doesn't need treatment and can I think be driven more easily than others as it is very stiff, but that might bring on a barrage of quips about coastal engineers and groynes.

All the best.


Edited by ferdinand, 09 March 2016 - 09:04 AM.