Tricky retaining wall.

[zoothorn]

Hi chaps, buying a 20+ year neglected stone cottage = a good few threads! some coinciding (whist I wait on gate quotes etc).

 

I have a tricky sloped garden end. I want to level (for a log cabin) by putting in a retaining wall/ barrier RHS.. & pulling soil across to fill from LHS.

Its an extremely important job to get the right plan & I've entertained many ideas (a prior thread too), builders out.. but something nags structure-wise of the retaining wall. So I'd like to refresh: perhaps some new ideas, maybe from a "structural landscaper".. would anyone best fit that bill on here?

 

Its a narrow end area, & dips to a brook RHS. Brook swells quite significantly. Pink batons show the slope.

The brook in pic1 is far RHS. I want the wall up, from approx where farthest Right baton's pointing down to. (Pic3 reverse view)..

 

Thanks- zoot schmootzer

 

 

 

 

 

 

 

 

[Russell griffiths]

Gabion baskets on the lower level and another row on the upper level. 

Edited April 22, 2019 by Russell griffiths
Spelling.

[ProDave]

I thought from a previous discussion you were just going to build it out on stilts over the bank.

 

What is that the other side? Your land or a neighbours garden?

[zoothorn]

1 hour ago, Russell griffiths said:

Gaboon baskets on the lower level and another row on the upper level. 

 

Hi Russell.

 

Would I be right these are the wire rectangular things filled with big stones? its a suggestion that's not yet been given, & I do see them around (so wondered why not suggested).

 

Ok Ive no idea on them, what they are for exactly. Could you expand?

[newhome]

You can use them for retaining walls. 

 

 

[zoothorn]

19 minutes ago, ProDave said:

I thought from a previous discussion you were just going to build it out on stilts over the bank.

 

What is that the other side? Your land or a neighbours garden?

 

I hadn't decided. It was one of a few ideas, I think, but as said nothing is 'clicking/ that's it!'. I want to go back a step, ask as many opinions as possible again with a fresh approach- ideally to see if there's either a "structural landscaper" type person on here who can help.. or if not, a consensus of opinion on what kind of retaining wall.

 

What I did have top of list, was "ground screws". But thinking more, its far from an easy proposition because of such a large discrepency of slope.. & nature of the soil is poor/ not very solid. Also it doesn't make use of this slope area, which I want to pull down into the wall void to create the ground needed to level.

 

If you look at pic3 (reverse) I'm thinking of putting in a line of retaining barriers, below the LHS crest of my slope all way along (right up to that horrible n'bors seating area ~ approx 10m long x 1m high) in order to level/ widen out this nightmare garden slope topography. But I don't need anything HD to do this retaining looong barrier: posts whacked in + french oak beams can be used here.

 

The retaining wall for the cabin area/ the lower 1/4 of garden, the area in Q here, needs -much- more solidity than oak beams against posts: including more height (bc its stemming from right down near brook, the land just dips down here) involved & alot more earth pulled down from the slope into it.

 

So I need a strong retaining wall plan. I'll get my builder to do it, in order to make SURE its properly made. Then the easy bit is getting in a digger (bloke up lane's got one.. so I wag notes in front of his nose) to pull the baton area soil down into/ against the new barrier.. or even I shovel by hand.

[zoothorn]

Hi newhome, I had thought the actual construction of the gabion baskets would be do-able.. but what this clip doesn't tell me, is for what -purpose- it has been chosen/ what's it for? a fancy bird table? a footing for a monster truck museum?

[newhome]

1 minute ago, zoothorn said:

Hi newhome, I had thought the actual construction of the gabion baskets would be do-able.. but what this clip doesn't tell me, is for what -purpose- it has been chosen/ what's it for? a fancy bird table? a footing for a monster truck museum?

 

There are videos on Youtube showing how to use them for retaining walls. 

[zoothorn]

Ok that's good & I'll have a look. But you see I don't think I'm the person to choose, that this is the correct approach. That's the very purpose of the thread. I need help in order to make the decision from folks, ideally who have experience of making retaining walls.

 

If anyone's done -any- sort of retaining wall, would they reply? a landscaper/ anyone? if anyone's done one using these gabions.. brilliant PLEASE PLEASE would you tell me all about it, & maybe voice your opinion on whether its a good thing to use, in my situation?

 

thanks. zoot

[Jeremy Harris]

I did a load of calculations for using gabions for a retaining wall, back when I was thinking of using them for our big retaining wall.  Not hard to design a stepped retaining wall with them, TBH, as there are guides from some of the manufacturers available.  Their big advantage is that they are pretty low tech, easy to DIY and can be filled slowly by hand.  They are also probably the cheapest way to make a reliable retaining wall.

 

[Declan52]

There are plenty of dry stone options using either real stone if you can get it cheap or concrete blocks. Either way doesn't require a concrete foundation 

I used a dry stone concrete block on my drive.  Only thing is it might be an expensive option as you won't really see much of it. 

Gabions and stone and some wire to tie it together is about as low tech as you can get.

[zoothorn]

Hi Declan- that looks splendid, but I won't need aesthetically good as it won't be seen down side of bank (in fact I entertain idea of most horrible looking.. so my sod n'bors have a wall of concrete to look out on.. is good).

 

I am looking for most effective, & cost effective: even going OTT is good as I just cannot have the situation of the cabin creeping down on one corner even 1 inch.. so mitigating against this is absolute priority.

 

So how would a series of these gabions work in my situation? I can't even visualise what a retaining wall of these might consist of/ how might I plan them with structure in mind? its this structural area, even say having chosen the gabion way, that I have not one iota of an idea of to proceed.

[zoothorn]

 

5 hours ago, JSHarris said:

I did a load of calculations for using gabions for a retaining wall, back when I was thinking of using them for our big retaining wall.  Not hard to design a stepped retaining wall with them, TBH, as there are guides from some of the manufacturers available.  Their big advantage is that they are pretty low tech, easy to DIY and can be filled slowly by hand.  They are also probably the cheapest way to make a reliable retaining wall.

 

 

Hi JSHarris.. if it were you, with this tricky end of garden to level, what would you do? what method would you choose?

 

Anyone else.. same Q. What would you do?

 

Ive looked at gambion clips, but cannot get anything similar (bar this one which infuriatingly stops just when you need it to continue https://www.youtube.com/watch?v=zD5BzXteIYs).. so cannot possibly know what sort of configuration, or size I'd need. There's one incredibly complex calculater clip.. but I haven't a clue what a is from b.

 

@Onoff if he's out there.. your opinion on this would be really welcome.

 

Edited April 22, 2019 by zoothorn

[Onoff]

Why not hire a digger for the day and carve a flat terrace to build the cabin on?

 

I'd look too carefully at managing that slope against future soil erosion by maybe encouraging plant growth with some binding root system. I'm no gardener though. Again terracing the slope can help with this.

 

They're rebuilding some cottages near me on a slope using a gabion retaining wall. Will try and grab a pic tomorrow.

 

Tbh I'd be digging some metre cubed holes and chucking some beefy timbers in as uprights to support a cantilevered deck for a cabin. I'd stand the timbers on the concrete in a Metpost type bracket rather than in the concrete. If things do sink then jack up and pack. 

 

Tbh unless you're going to spend money and employ a structural engineer along with possibly ground surveys you're going to just have to go by gut and enjoy the ride.....even if it goes wrong.

 

 

[zoothorn]

@Onoff why not carve a flat shelf.. because I cannot use a digger. And bc if I carve a shelf into such a steep (its over 45*) & narrow area there will be nothing to stop it creeping down twds RHS/ the brook (I'd surely need a retaining wall anyway even doing this idea.. or erosion will just wash the poor bank soil gradually down into the stream RHS.. & a retaining wall LHS too?).

 

And another reason: because some of the point of the retaining wall, was to 'fill it', from pulled soil from the LHS bank down, to eleviate this area too/ makes more space of this area: its alot of road spoil mixed with earth flung down & means this slope area intrudes across half of my property at this narrow end area.

 

The idea of using a digger to flatten the base for some gambions tho.. seems like an idea. I am worried tho that even if such a base is well prepped, as its only a foot above the brook water.. & when it swells & becomes fairly vigorous as it does, then covering this base.. will it just wash it away?

 

This is why I was hoping for a "structural landscaper" might see the thread & voice an opinion.

[Jeremy Harris]

17 hours ago, zoothorn said:

 

 

Hi JSHarris.. if it were you, with this tricky end of garden to level, what would you do? what method would you choose?

 

 

In your position, I think I'd either use gabions, if I didn't mind the work involved in digging out flat areas for them, and filling them with stone, or I'd look at using screw minipiles, and putting them in by hand.  The latter would probably be a lot less work, but might incur a higher cost.

[zoothorn]

 

12 minutes ago, JSHarris said:

 

minipiles..

 

(Ive got some of these from sitting in the buff like this!)

 

 

Do you mean "ground screws?"

 

 

[Jeremy Harris]

37 minutes ago, zoothorn said:

 

 

(Ive got some of these from sitting in the buff like this!)

 

 

Do you mean "ground screws?"

 

 

 

 

Pretty much.  Here's a video showing a Finnish system being installed by hand:

 

 

[Ferdinand]

Do you have a photo of the brook in full spate?

[Mr Punter]

If the soil conditions are suitable I would look at building the whole thing on stilts using screw piles as suggested by @JSHarris.

[ProDave]

19 minutes ago, Ferdinand said:

Do you have a photo of the brook in full spate?

+1

 

If it is anything like our burn, it can get quite full and quite angry.  I would not want to be doing anything to the bank below "flood level" that may impede flow or create turbulence.

 

Under spate conditions, it is only the vegetation that keeps the soil in place and stops it getting washed away.

 

 

[zoothorn]

 

22 minutes ago, JSHarris said:

 

minipiles..

 

@JSHarris look more sturdy than ground screws, but the same idea which I sort of discounted, to start the thread/ idea afresh again.

 

You see what I have, is a long thin area of garden. You can see the bugger of a slope looking back in pic3 (#1). In order to make use of this huge slope which extends (widthwise, across the narrow area of land I have) for majority of garden.. I need to flatten-widen it. So I put in some sleepers as a barrier on the apex of the curve. Easy.

 

If I'm doing this sleeper-wall just ahead of my trickiest/ maximum slope/ minimum land width/ lowest end of my land.. I need something to fill it/ soil. So the best idea to get it from.. is this big slope area/ road scree & soil down at the tricky end (where my pink batons are).

 

But I have a fair bit of soil left. And I have yet to think how to sit my cabin onto the narrow/ tricky end bit. So you see how the idea in principle of -extending onwards- the sleeper barrier lawn idea.. just in heavy-duty format (*this is what I'm yet to establish what exactly- the nub of the thread), for the cabin load to sit onto, by filling it with (the remaining/ likely most of) soil from pink baton slope area.

 

 

 

 

[zoothorn]

28 minutes ago, Ferdinand said:

Do you have a photo of the brook in full spate?

 

alas not.. but it gets max about 2 ft high & widens to 5 ft or so. Its usually 1ft wide.

 

What I need here, is a "waterproof" retaining wall/ bank. Which points me back to gambions, as they do have this 'waterproof' aspect. The bit that's eluding me in principle is the flat prepped 'trench' of say D100mm into which the gambion sits. Concrete? surely the soil underneath can get washed away. Soil? Im not sure how again it might shift the gambions 'footings' by angry brook action. Compacted hardcore maybe?

 

Then what's to stop the gambion wall falling over into brook, by the weight of the soil pulled down against it? (& cabin ontop too)

[Jeremy Harris]

Gabions need to sit on a compacted base, something like MOT 1, whacked down.  They seem to work OK as a way of controlling bank erosion along streams and rivers: