Slopes

[eandg]

Been told that 1:1 (i.e. can have a slope from 4m height to ground level over 4m length) is generally okay if you were to pin it with some geotextile until planting had established itself, but can't find any info online. Is that correct?

[Simplysimon]

surely the angle of repose is subject to the type of soil?

[eandg]

11 minutes ago, Simplysimon said:

surely the angle of repose is subject to the type of soil?

Aye, sounds right now I've googled angle of repose. Stupid question - all new to me and just checking out what a groundworker told me on site when discussing options for spoil. Will run it by the engineer. 

[Marvin]

Depends also on what is at the top level....

 

I thought geotextile and planting was about defence against erosion not the possibility of land slip. 

Edited January 15, 2022 by Marvin
Clarification

[Conor]

Depends on the specific modulus of the soil. Ours has a modulus of two and were able to batten slopes to more than 60°.

 

This will give you a good idea of slip angles. 

 

http://www.geotechdata.info/parameter/angle-of-friction

 

NB, enough rain can wash away and collapse any type of soil bank at any angle..

 

We planted a load of wild grass and flower seeds on our spoil heaps, really helps keep the surface together and reduce wash off.

 

We have a silt fence at the bottom of the site to prevent wash off to the river (planning condition)

 

 

[ToughButterCup]

14 hours ago, eandg said:

Been told that 1:1 (i.e. can have a slope from 4m height to ground level over 4m length) is generally okay if you were to pin it with some geotextile until planting had established itself, but can't find any info online. Is that correct?

 

For us,  on 'Made Ground' , (spoil from an old clay quarry) , the answer is yes, its OK. A 4m high bank over a little more than 100 meters length.  No geotextile , but far too many nettles, brambles rampant,  some builders' rubble mixed in, trees at the bottom of the bank . I suspect the trees drain the bank a good bit.  Where our children used to scramble up the bank - or badgers burrowed into  it (and now  rats have taken over) , we 'got rid of' a few telegraph poles and let the animal excavations collapse in their own good time. The bank is now a Great Crested Newt reserve: we let it go wild most of the year. Then knock it back a bit at back-end: or not if I forget .....?

 

Pinning it pro tem with geotextile and getting some ground ivy in quickly might just be what you need.

[eandg]

4 hours ago, ToughButterCup said:

 

For us,  on 'Made Ground' , (spoil from an old clay quarry) , the answer is yes, its OK. A 4m high bank over a little more than 100 meters length.  No geotextile , but far too many nettles, brambles rampant,  some builders' rubble mixed in, trees at the bottom of the bank . I suspect the trees drain the bank a good bit.  Where our children used to scramble up the bank - or badgers burrowed into  it (and now  rats have taken over) , we 'got rid of' a few telegraph poles and let the animal excavations collapse in their own good time. The bank is now a Great Crested Newt reserve: we let it go wild most of the year. Then knock it back a bit at back-end: or not if I forget .....?

 

Pinning it pro tem with geotextile and getting some ground ivy in quickly might just be what you need.

Thanks - that's reassuring. Engineer says 45 degrees should be fine. Plan will be to pin it, spread as much topsoil on as we can stretch to and seed with wildflowers asap. 

[James94]

Could you not use something like this or something similar.

Regards. James

 

[ToughButterCup]

13 hours ago, eandg said:

....  and seed with wildflowers asap. 

 

Thats quite hard to achieve. Topsoil is often too 'rich'

Keep back some poor soil and small crushed stone as a topping. We've had poor results so far, so I'm hoarding clean stone and remnants of sharp sand in an effort to duplicate the poor soil in which many wild flowers grow.

 

Anyway, best of luck! 

Before and after photos would be good ?

[Conor]

16 hours ago, eandg said:

Thanks - that's reassuring. Engineer says 45 degrees should be fine. Plan will be to pin it, spread as much topsoil on as we can stretch to and seed with wildflowers asap. 

 

Keep the topsoil in a separate heap. It'll soon be covered on grasses and nettles. The subsoil would benefit from the wild seed mixes as they prefer poor soil anyway. Ours did really well even though we didn't sow until June. Field marigolds, wild mustard and cornflowers did particularly well.

 

 

Edited January 17, 2022 by Conor

[eandg]

11 minutes ago, Conor said:

 

Keep the topsoil in a separate heap. It'll soon be covered on grasses and nettles. The subsoil would benefit from the wild seed mixes as they prefer poor soil anyway. Ours did really well even though we didn't sow until June. Field marigolds, wild mustard and cornflowers did particularly well.

 

 

 

Thanks, and looks great - done some reading since and read that Autumn is best for seeding but we'll be putting it down in Spring. 

 

2 hours ago, ToughButterCup said:

 

Thats quite hard to achieve. Topsoil is often too 'rich'

Keep back some poor soil and small crushed stone as a topping. We've had poor results so far, so I'm hoarding clean stone and remnants of sharp sand in an effort to duplicate the poor soil in which many wild flowers grow.

 

Anyway, best of luck! 

Before and after photos would be good ?

Thanks, and will do.

[redtop]

We had exactly this. My plan was geotec membrame, top soil, seed. However that got delayed and after a single spring / summer plants have completely taken over and it hasn't moved a jot and neither are we getting any soil washed away. So if you can leave it a bit then do and see what nature does. Might save a few quid and effort