Anyone already done this

[Gone West]

Our property is on the side of a hill and consequently the garden is a mix of terraces and slopes. There is one slope which varies in height from 2m to just over 3m and has an average angle of around 60 degrees. We want to tidy up the front of the slope and I had the idea of using hessian sand bags filled with soil which would be stepped back slightly to keep the angle the same. Then the bags could be slit and planted with ground cover plants. Anybody done this before?

[markc]

Hessian bags will soon rot and the soil will ‘flow’ down the slope until it settles at its angle of repose - this will be greater / steeper depending on the type and amount of vegetation present when the hessian rots.

[saveasteading]

1 hour ago, Gone West said:

Anybody done this before?

It's a standard procedure for appropriate slopes. you can buy hessian impregnated with seeds.

But you are going to need plants with roots that go deep so that it ties the ground together through the slip planes.

I think these sheets are usually spiked quite deep for the same reason.

It would be quite a risk to rely on this.

What about small retaining walls to reduce the height and gradient of the slope?

 

Slip circles are remarkable and can go deep. There is a radius point somewhere in the air and the failure circle really does rotate about it. Civil Engineering can be fun. Mohr than that I can't remember though.

 

[ProDave]

I recall years ago an employer of mine wanted to enlarge their car park.  They used this sort of system where a wooden former was put in place with a much steeper angle than the natural angle of repose.  A layer of soil was poured and compacted against this former.  Then the former removed and the material and seeding wrapped over the exposed edge.  Then the former replaced a layer up and another layer of soil laid and them more material and seeding.  It was repeated until they reached the top.

 

It did succeed in holding up the enlarged car park, but I would not want to trust it to hold a building up.

[SteamyTea]

13 hours ago, saveasteading said:

Mohr than that I can't remember though.

Very good

 

https://en.wikipedia.org/wiki/Mohr's_circle

[Gone West]

14 hours ago, markc said:

Hessian bags will soon rot and the soil will ‘flow’ down the slope until it settles at its angle of repose

 

14 hours ago, saveasteading said:

What about small retaining walls to reduce the height and gradient of the slope?

 

Thanks for your suggestions. The slope has been there for at least 50 years. The ground generally is very stoney with large areas of sandstone and shale. I just want to tidy it up a bit. I would want the hessian to rot away eventually and for the ground cover to have rooted well into the soil. I would use evergreen plants, such as Bearberry, that would help protect the soil from driving rain.

[JohnMo]

16 hours ago, Gone West said:

Our property is on the side of a hill and consequently the garden is a mix of terraces and slopes. There is one slope which varies in height from 2m to just over 3m and has an average angle of around 60 degrees. We want to tidy up the front of the slope and I had the idea of using hessian sand bags filled with soil which would be stepped back slightly to keep the angle the same. Then the bags could be slit and planted with ground cover plants. Anybody done this before?

I did a small area on a 50 deg slope, a couple of years later the bags have all rotted away, but it does give time for the plant roots to take over.  Much less labour intensive is the correct landscaping mesh then back fill with soil.

[JohnMo]

Big scale

 

[saveasteading]

18 minutes ago, JohnMo said:

the correct landscaping mesh

If it rots. A lot are plastic and will be in the soil forever.

[Gone West]

14 minutes ago, JohnMo said:

Big scale

That looks interesting. I guess the mesh is plastic and pinned into the soil. I doubt I would be able to buy a 25mx3m chunk.

[saveasteading]

I think the way the polders were originally protected was by banging in sticks quite deep but sticking out, then plants roots can cling to them.

So mh suggestion is hessian, pinned down with sticks from plang thinning, and then grass seed either over or under it. And/Or your bear berry inserted in slits.

 

I hope you keep us informed of progress and success.

[SteamyTea]

20 minutes ago, Gone West said:

I doubt I would be able to buy a 25mx3m chunk.

Would those ground mats that are used for vehicle parking work?

 

[Gone West]

1 minute ago, SteamyTea said:

Would those ground mats that are used for vehicle parking work?

I have used those before and they would be too rigid I think. I think I'll persevere with using hessian in some form.

[SteamyTea]

4 minutes ago, Gone West said:

I think I'll persevere with using hessian in some form

There is always gill nets, they wash up on the shore often enough.

[JohnMo]

57 minutes ago, Gone West said:

doubt I would be able to buy a 25mx3m chunk.

Think it came in manhandled sections and was pinned to the ground with bent rebar pins.

[Ferdinand]

It sounds like you need a flexible system not a rigid grid.

This was done on one the very first Grand Designs, back in 1999, with Kevin being introduced to landscaping mesh as used on embankments, which comes as a folded concertina of large hexagonal cells. This was when he was still an interior decorator and had hair. Series One Episode 4.

Probably there are now "biodegradable over X years" products made of organic materials.

The Amersham Water Tower.

Lovely background music.

Here's the C4 link. You'll need to tolerate some adverts. The first GD with application of "commercial architecture" techniques. They have done a couple of revisits since.

The bit you want is at about 37 minutes, but the whole thing is worth a rewatch.
https://www.channel4.com/programmes/grand-designs/on-demand/26262-004

Look under "soil erosion prevention" or "gravel retention" or "GEO grid" categories.