River bank edging - Which timber?

[HexusOdy]

Hi Guys,

I wanted to ask if anyone had experience of timber that was going to be submerged in water?

I want to shore up a riverbank at the bottom of my garden. It's not a huge river, in fact in Summer with farmers raiding it and dry weather it can get get down to less than a foot deep. But in winter it's decent tributary about 20ft wide and 3ft deep (its deeper in Summer and winter in some section but I'm not far from a culvert and they don't dredge anymore). Anyway..

I know how to shore it up with piles/boards/backfill but I'm not sure what timber to use.

The ultimate choice would be Ekki (Azobe) but it's hard to source and expensive (It's also stupidly tough to make holes in). If I was in NL it would be happy days, they use Ekki a lot there but domestic/small scale timber shoring isn't common place in the UK.

The easiest/cheapest is greek oak. It should be reasonable on the not rotting front but as the river level changes a great deal through the seasons I could have serious problems with shrinkage in the summer and gaps are less than ideal. Although I'm not sure how much it will shrink outside. I could possibly get it machined with a T&G to try overcome this.

Obviously woods like Ipe would work but I don't want to have to sell my house to afford to do the work.

Any ideas?

 

[MARK.B.]

Green Heart i think its called the stuff they use on the beach groins ,tough as old boots and will outlast your grandchildren if you have any that is

 

[maitland.selwyn]

This is not really a reply to your question so apologies, but over here the "river police" won't allow anything much to be installed on the river banks - doesn't stop people using concrete posts and railway sleepers - but many years ago when I was trying to keep them happy we drove in posts and wove willow branches around the posts. It created a "living" edge to the river that runs through my property and worked for a while. The willow actually continued growing for a couple of years. (One of the "functionaries" was actually armed with something like a 357 magnum, so any attempt to keep him happy seemed worthwhile.)

 

[HexusOdy]

Green Heart i think its called the stuff they use on the beach groins ,tough as old boots and will outlast your grandchildren if you have any that is

Yes I looked at greenheart too but like Ekki it's hard to source and expensive.

 

[Ollie78]

I would say wood is going to be a very expensive method. I have often seen people using steel pilings to shore up banks. I am guessing they are cor-ten steel or something.
Green heart is going to cost a fair bit, it's crazy stuff, super dense.

Ollie

 

[TheTiddles]

Is this a DIY job exclusively? The canals use steel pilings that lock together, but the tool to drive them in is not small and subtle.

Gabions would be the old fashioned way of doing it, and also the modern way with stainless cages and cobble they look lovely in the right circumstances.

Aidan

 

[Blackswanwood]

Is Willow spiling an option?

 

[HexusOdy]

Is this a DIY job exclusively? The canals use steel pilings that lock together, but the tool to drive them in is not small and subtle.

Gabions would be the old fashioned way of doing it, and also the modern way with stainless cages and cobble they look lovely in the right circumstances.

Aidan

It's not a huge job. It's not easy for sure but it's only about 18" high and by the time I do the job I can probably do it while barely getting wet. The toughest part of it is driving in the piles which need to go in a good 4ft+ but being a river bed it should be pretty soft.

I considered Gabions but they are hefty and I think too big for the job. Also some access issues with getting all the rocks to fill them to the site.

The total length is about 18m but around 7-8m of that is already very stable with tree roots. It's the remaining 10-11m I need to shore up and it's gradually losing mass year on year.

So it's about 20 piles (75-80mm) and about 24-27 2.4m 150 x 25 boards (plus a load of bolts and ground anchors). It's definitely DIYable in this case. It's kust getting the right timber and not breaking the bank.

 

[HexusOdy]

Is Willow spiling an option?

It could be, but I think I would have more trouble doing that myself and thus may cost more to get someone in.

 

[Blackswanwood]

It could be, but I think I would have more trouble doing that myself and thus may cost more to get someone in.

The work doesn’t sound that different to what you describe above. It seems to be being used increasingly on the rivers by farmers near us. They just bang in stakes and weave the willow between them. Some make it like basket work and others just seem to shove it in but within a year you cannot tell the difference as the willow has taken over. It seems to work very effectively.

 

[Qwercus]

Near where I live on the South Coast is a yard where the Environment Agency dump used timber from sea defence work. I think it's mostly Greenheart or Jarrah. It's obviously damaged in some way but could be recycled for smaller jobs. The problems would be; 1, it's extremely heavy, 2, it's extremely hard, so resawing would be a problem. Some of the piles are 12"x12" in section!. I'd have thought there would be similar places near to you on the East Anglian coast.

 

[skeetstar]

Elm. The piling of the old London Bridge were elm, they lasted hundreds of years. Nelson ships were oak above the waterline, but elm below it.

 

[joshvegas]

I do a bit of river restoration design from a flood perspective. I'm not going to comment on wether you should or shouldn't be working in the river, thats for you you and the EA/SEPA/NRW to workout. Or the health and safety of mucking about with an unengineered solution. Also its not clear from your post if its just retention or erosion protection?

Have you considered plastic?

Exactly the same concept as steel but you can lift them up and walk about with them. They're cheap. You can get them with a woodust coating to promote growth on them to get a nice slimy habitat. Atleast one brand is made by a upvc window extrusion manufacturer out of all the offcuts.

You can also get them as "logs". Which allows you to plant something in the top to give you a reasonable hidden top while maintaining support. Liniar produce them, i'm sure others do. Generally i thing you pin them rather than drive them in. They look a bit crap when new in my opinion but at the watersedge with some weathering they'd blend fairly quickly. Aslong as the aren't going to be heavily abraided your chance of plastic pollution is fairly low (obviously think about where you cut them

Don't use gabions, they're great for retention but they're not great in flows and you'll need a fair heap of rock. You also need to get them onto something solid which might involve a fair bit of unnecessary excavation.

Willow spiling is lovely and a really effective natural bank protection but if you want to actually see the river in three years time... I wouldn't recommend! there maybe other vegetation options! If its only 18inches you could probably use ******* or fascines, if and peg them, i can't remember which is the dead wood option. These options will help promote sedimentation and reverse erosion if you are in that situation. If you don't mind a bit of extra privacy go to town with vegetation its a great long term solution and has loads of benefits including more wildlife in your garden.

If you were prepared to soften your bank slope to a max angle of 80degrees you could use something like FlexMSE to build a vegetated retaining wall. Again pretty cheap and it's constructed of earth filled bags so a bit of hard graft is basically all you need. They look nice/invisible and get a nice bit of vegetation in there, advice on what to seed would get you a good planting across the different conditions. Its an effective system and you get structure bit you're getting resilience from the vegetation because its a bag wall you can produce something natural looking with slope variation.

Not bad for my second post.

 

[pe2dave]

Different approach? Plant willow slips along the bank. within 2 years they will hold it.
Experience from a local river and the workers there.

 

[bourbon]

Get the canal and rivers trust advise? see what they recommend

 

[Woody2Shoes]

Different approach? Plant willow slips along the bank. within 2 years they will hold it.
Experience from a local river and the workers there.

+1 for this - the best natural way to stabilize a bank would be planting willow and/or alder. Alder timber would be good in wet ground too, if you were going for the 'woven' effect mentioned above, alder would be good for the stakes.
I wouldn't use oak in the ground. I would not use any tropical hardwood, except perhaps reclaimed.

 

[stuckinthemud]

If you have to go timber and its staying submerged, elm is perfect, but, it is very expensive and not so rot proof if it is out of the water periodically. Fine fully submerged, not fine if it goes through wet/dry cycles

 

[HexusOdy]

I do a bit of river restoration design from a flood perspective. I'm not going to comment on wether you should or shouldn't be working in the river, thats for you you and the EA/SEPA/NRW to workout. Or the health and safety of mucking about with an unengineered solution. Also its not clear from your post if its just retention or erosion protection?

Have you considered plastic?

Exactly the same concept as steel but you can lift them up and walk about with them. They're cheap. You can get them with a woodust coating to promote growth on them to get a nice slimy habitat. Atleast one brand is made by a upvc window extrusion manufacturer out of all the offcuts.

You can also get them as "logs". Which allows you to plant something in the top to give you a reasonable hidden top while maintaining support. Liniar produce them, i'm sure others do. Generally i thing you pin them rather than drive them in. They look a bit rubbish when new in my opinion but at the watersedge with some weathering they'd blend fairly quickly. Aslong as the aren't going to be heavily abraided your chance of plastic pollution is fairly low (obviously think about where you cut them

Don't use gabions, they're great for retention but they're not great in flows and you'll need a fair heap of rock. You also need to get them onto something solid which might involve a fair bit of unnecessary excavation.

Willow spiling is lovely and a really effective natural bank protection but if you want to actually see the river in three years time... I wouldn't recommend! there maybe other vegetation options! If its only 18inches you could probably use ******* or fascines, if and peg them, i can't remember which is the dead wood option. These options will help promote sedimentation and reverse erosion if you are in that situation. If you don't mind a bit of extra privacy go to town with vegetation its a great long term solution and has loads of benefits including more wildlife in your garden.

If you were prepared to soften your bank slope to a max angle of 80degrees you could use something like FlexMSE to build a vegetated retaining wall. Again pretty cheap and it's constructed of earth filled bags so a bit of hard graft is basically all you need. They look nice/invisible and get a nice bit of vegetation in there, advice on what to seed would get you a good planting across the different conditions. Its an effective system and you get structure bit you're getting resilience from the vegetation because its a bag wall you can produce something natural looking with slope variation.

Not bad for my second post.

Great post, thanks.

It's part retention, part erosion. I want to put back a section that has eroded over time (about 60cm at the far end tapering down over about 10m) and to stop it eroding again in the future. The amount of horizontal space it consumer is also important which is why gabbions and some of the other suggestions here wouldn't really work. Which is why the retaining wall appealed as it's a completely vertical solution and lets me rebuild and stops future erosion.

I like the plastic. Liniar have some great options. The problem is where do you buy it? I can see lot's of information about it but not anywhere that sells it.

 

[Spectric]

Be careful because if what you do to protect your land subsequently impacts someone else you can have issues. Also I have seen a wall that was put in to stop errosion but is now an island, the water ended up cutting behind it, taking on nature is never easy.

 

[Avery]

Hi Guys,

I wanted to ask if anyone had experience of timber that was going to be submerged in water?

I want to shore up a riverbank at the bottom of my garden. It's not a huge river, in fact in Summer with farmers raiding it and dry weather it can get get down to less than a foot deep. But in winter it's decent tributary about 20ft wide and 3ft deep (its deeper in Summer and winter in some section but I'm not far from a culvert and they don't dredge anymore). Anyway..

I know how to shore it up with piles/boards/backfill but I'm not sure what timber to use.

The ultimate choice would be Ekki (Azobe) but it's hard to source and expensive (It's also stupidly tough to make holes in). If I was in NL it would be happy days, they use Ekki a lot there but domestic/small scale timber shoring isn't common place in the UK.

The easiest/cheapest is greek oak. It should be reasonable on the not rotting front but as the river level changes a great deal through the seasons I could have serious problems with shrinkage in the summer and gaps are less than ideal. Although I'm not sure how much it will shrink outside. I could possibly get it machined with a T&G to try overcome this.

Obviously woods like Ipe would work but I don't want to have to sell my house to afford to do the work.

Any ideas?

I live in brighton so this comes up a lot. Green Heart is what was traditionally used but its mostly gone now and you will struggle to source it and you would have to remorgage anyway to buy it. The romans used Elm for their irrigation channels and obviously Oak is pretty longlasting, other than that youll have to sell your house to buy some teak. You could live down by the river in a tent. Might be worth it.