Kitchen Garden Forum

In fact, it's more like a wall.

My new plot is on a steep slope. It's been freshly created and has been made as 2 wide terraces with a steep slope/wall between the 2. This slope is approximately 5 feet high and at least 45 degrees.

Given the steepness and height has anyone any advice as to how I should shore it up? I'm considering adding a smaller terrace (basically, a raised bed) into this wall to distribute the weight and make best use of it as a growing space. Is this a good idea?

Any advice appreciated. I just don't want my shiny new allotment sliding down onto the road over the winter...

Thanks,

Jake

Dear Jake, with out actually seeing the sight, i feel it is very hard to give you a answer, sorry not to be of much help.

do you want third small level terrace between the existing ones? if thats the plan you need to build a 2 1/2 foot tall wall at the bottom of the 5 foot high slope, dig out the top half of the slope and build up the bottom half of the new terrace, then build another wall at the top end to hold up the highest existing terrace. remember water must be able to drain out through both walls, often done by either not putting mortar in some of the vertical joints in the lowest row of blocks or by building in short lengths of drain pipe.
or you can dig down half way up the sloping bit and build a 5 foot stronger wall , then throw the bottom half of the slope on to the top half to extend both existing terraces.
i,d go for the two small walls , 6 inch concrete block on a concrete foundation should do it.

http://www.jakemc.co.uk/plot45/?attachment_id=4
http://www.jakemc.co.uk/plot45/?attachment_id=5

Does this help?

Thanks,

Jake

Gosh Jake you do like a challenge, one good thing it looks some nice topsoil.
I think a lot depends on how much money you want to spend. To do a proper job it would be best to tackle it as Richard suggests.
You could also retain it with sleepers but these will have to be dug into the soil to a good depth.
Another way, and i'm not sure how well it would work, would be to plant the slope up with plants, maybe fruit trees or bushes, the roots of which will help to hold the banks together.
Hopefully you will get some other ideas from other people as well.
How have the other plot holders gone about retaining theirs plots.

Thanks Richard and Mr H.

Adding a third, small terrace is definitely what I've been thinking. Do I really need to build a brick wall? I naively thought that a well staked wall of planks might do the trick... How deep would sleepers need to go?

And what about the very bottom of my plot? In theory that should be the allotment associations responsibility, I suppose, but I'm not counting my chickens...

Other plots on the same hill are all made up of 6 or 7 smaller terraces or they're just steeply sloping, hence my post: I've never seen a plot built quite like this :-/

And I suppose I do like a challenge but the alternatives were just as steep and swamped with brambles...

Thanks,

Jake

Pave it and charge local skateboarders £1 a go.

Hello Jake, i would normally let sleepers in the ground to half their height, if they have five feet above ground dig them in two and a half feet deep.
I think a lot depends on whether you are trying to stop a land slide or just the topsoil washing off.
Just wondering what the subsoil is like, if it is fairly solid you won't get a lot of trouble with it moving.

Jake, have you got deep pockets?

See http://www.railwaysleeper.com/railway%2 ... 0table.htm cheapest os £18.80 inc VAT.

Each will do a width of ten inches and is eight foot six inches long. Cut in half, let in two feet and you can support two feet.

so you have the measurements, give us a fright.

Cost me pushing £200 to build a base and edges for two beds on a 12 X 8 greenhouse on a slight slope.

Mr H, the subsoil is clay so I think you're probably right.

I haven't dug very much yet (I only got it on Friday) but my biggest problem so far seems to be that there's only a few meagre inches of topsoil before I'm into solid clay. I'll have a dig around other parts and see what else I find. The plot is newly created, probably with leftovers from soil dug out to create the new haulingway so I'll need to have a closer look. Especially considering the cost of those railway sleepers.

Thanks for all your advice. I'll have a dig, get someone who knows about structural engineering (I've a friend who builds bridges - big bridges - for a living) and let you know.

Although the skateboard park option appeals too...

Jake

having now seen the pics and its an allotment not your own garden i wouldnt invest the money in hard landscaping of any sort. the aim should be to stabalise the topsoil on the slope using plant roots, fruit bushes and grass perhaps. grass could be cut with a strimmer or even a hover mower. you could even bury some plastic netting just under the surface for extra binding. first things first though is to talk to the other plot holders to see if there is a problem with either topsoil washing off or general collapse of the slope.

The problem with anything solid like concrete and bricks apart from expense is that if the pressure of the soil above gets too great then in time it might push the wall over then you will have a big job clearing it to start again. You might like to consider tanalised fenceposts, easier to repair if they are pressed down but do lean anything backwards towards the bank to use its weight. When you go on motoring thrips have a look at what professionals have done in cuttings.
Allan

I had a pretty similar problem when I bought this house, two 45/360 slopes over heavy clay. Coming at this from a vaguely permaculture and experimental angle, I rejected terracing at you would be looking at walls all the time rather than plants.

I'm maintaing both banks so they don't get any more weedy, and, ...

front bank - planting potatoes to clean up the soil, and then I've planted a couple of ballerina fruit trees, with primroses round the base, which helps protect the rootstock. I've also sown some green manure.

Elsewhere I've also dumped manure and then grown courgettes/pumpkins, amongst the decorative shrubs, they work well on the slope, and give the neighbours something to talk about.

Elsehwere in the garden I've gone for self seeding flowers, fried egg plants, marigolds, and foxgloves do well, but hoping to bring in teasel. Dill/Fennel, and Kale are also positively appealing for edibles. I did initially try a wildflower seed mix, but there is just no chance of working the clay to a fine tilth.

At the back, a similar approach of potatoes first year, followed by fruit trees and bushes. (Blackcurrents, redcurrents) I did try cranberries but unsurprisingly they did not like it. Also putting in a box hedge at the top.

Overall the soil will slump down over time, and if loose, but generally clay is so, well, rock like, that it stays put. Watering in a problem, it all just flows down, so what I intend doing is putting across 'log swales'. That is get a log from the local woods, they are just lying around, pinning it in with a couple stakes, along the slope, just beneath the trees or bushes, and then using it to retain some leaf mulch, so that it will catch water as it goes down the slope.

This is very much a work in progress, but having started gardening on a slope, I'm glad of the challenge/opportunities. One final piece of advice for general digging over, use a chillingham type hoe, so you can stand at the top of the slope and pull stuff up, although a traditional spade has its uses, it is a tough way of digging over a steep slope.

cheers - Peter

This is probably a bit late, but this is one way to do it.

You can make a retaining wall with sleepers on their narrow edge up to 4 high. if you drill through them with a 1/2" auger bit (long one!)and pin them with 1/2" iron bar (used for reinforcing concrete). Knock the bar deep into the subsoil through the sleeper once in situ. Each layer can be pinned to the next or pinned all the way through to the ground.

The 'foundation sleeper' needs to be bedded down well into the ground and made leveland stable. 20mm scalpings are helpful at floor level. lay the sleepers like bricks - breaking joints. quite complicated polygonal layouts can be made.

I have done this incorporating steps into the design.


Another good product is 'dung walling' or stockwalling' - available from agricultural suppliers eg Mole Valley Farmers (no relation!) - It's basically 2" x 8" x 5m tongue and groove - about £12 a piece. Use with fence posts driven in behind and coach screws/clenched 6" nails to fasten.

i dont know alot about the subject but saw this incase helps sir
http://www.railwaysleeper.com/Kings%20landscaping%27s%20railway%20sleeper%20project.htm

looks quite strong and useful kind of what mole said.