I have been asked to come up with a solution for a bank

 that has been left after a lot of groundswork. 

It is 70- 60 degrees approx and about 4m high and roughly 15 m long,

 I have not measured anything yet as I have just received an email this evening.

 The bank has been cut back to allow a new winding pathway to be put in, so the

 existing soil has been removed and the subsoil is very hard.

  I will take some photo's tomorrow.

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Have you actually measured it as 60 -70 degrees as that is pretty bonkers. A slope that steep and 4m high is serious and will require proper erosion control measures rather than just a bit of landscaping. I would be inclined to get advice from a civils company at 60 degrees you would probably need geocell or maybe even soil nailing.

Any soil/ earth slope above 45 degrees and over 3 metres high should be considered unstable and therefore treated with almost the same respect you would a retaining wall at similar height.

I have measured the angle today and discovered that it is not as bad as I first thought,

 The bottom metre of part of the bank is 60 degrees but above that it slopes back at 35 degrees

for another 2.5 m and 40 degrees further along the bank.

 



Simon Smith said:

Have you actually measured it as 60 -70 degrees as that is pretty bonkers. A slope that steep and 4m high is serious and will require proper erosion control measures rather than just a bit of landscaping. I would be inclined to get advice from a civils company at 60 degrees you would probably need geocell or maybe even soil nailing.

Any soil/ earth slope above 45 degrees and over 3 metres high should be considered unstable and therefore treated with almost the same respect you would a retaining wall at similar height.

I have been working there today putting in some steps, and have had another

look at the problem. I think I will add sleepers along the base of the slopes, dug

in a couple of inches, as edges to the pathway, as they will catch any falling soil

during the peak holiday period. And the 60 degree section will require three sleepers.

Other work will have to be done in  Autumn/Winter.  

Anyone had any experience of using this pre seeded matting on a steep slope.

  

 

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Brick thick block retaining wall at least 600mm above path, 'rustic' rendering (ie don't need to be an expert) introduce or create top soil and it's a reasonable proposition to maintain whatever you decide to plant.

Hate the way builders and homeowners do these sort of things without thinking about the bit they are not looking at. If they had plant and a brickie on the site this job could have been done in half a day.

That sort of thing would fit the bill john and also companies supplying these kind of products tend to be very helpful and knowledgable.

Have you got a price yet? I looked at pre grown sedum matts for a similar slope until i heard how much they were.

 No I don't have the price, the property manager of the hotel

 sent me an email and asked for my comments, so not sure at

the moment if he wants me to do the job or not.  

Simon Smith said:

That sort of thing would fit the bill john and also companies supplying these kind of products tend to be very helpful and knowledgable.

Have you got a price yet? I looked at pre grown sedum matts for a similar slope until i heard how much they were.

 Yes it needs something at the base. The top soil will come from the bank itself

as approx the top quarter is reasonable soil, and the new wire fence running along

the top has been positioned back 5ft from the edge to allow the bank to sloped back

where the soil is.

John Baker said:

Brick thick block retaining wall at least 600mm above path, 'rustic' rendering (ie don't need to be an expert) introduce or create top soil and it's a reasonable proposition to maintain whatever you decide to plant.

Hate the way builders and homeowners do these sort of things without thinking about the bit they are not looking at. If they had plant and a brickie on the site this job could have been done in half a day.

Ouch. Way beyoond angle of repose for most soils.

That requires a properly enginered retaining structure.  Time to ask the designer/ client for their CDM assessment.

You will also need to think about working at height regs when maintaining the bank because staff could fall off a wall and hitting the nice shiney vehicles in the park with debris. Alternatively you could get a tractor and flail arm in there if you can get all the cars out of the way. Or how about grazing with mountain goats?

 A small stretch at the bottom of the slope is beyond the angle of repose,

  (soil/sub soil, 35 - 45 degrees) and this will have to have something in

front of it -sleepers possibly.

    The rest is ok, and the overall height of the bank will be reduce by approx

a quarter when the top is dug into for the top soil, this will obviously make it

easier to maintain the bank as and when it needs strimming. The plan is to have

grass and wild flowers, so not a lot of maintaining will be required.

James Dixon said:

Ouch. Way beyoond angle of repose for most soils.

That requires a properly enginered retaining structure.  Time to ask the designer/ client for their CDM assessment.

You will also need to think about working at height regs when maintaining the bank because staff could fall off a wall and hitting the nice shiney vehicles in the park with debris. Alternatively you could get a tractor and flail arm in there if you can get all the cars out of the way. Or how about grazing with mountain goats?

Here's an example I found ... One of many suppliers I'm sure ..:

http://www.phigroup.co.uk/solutions/gravity-retaining-walls/permacr...

 Yes it would work Gary, but cost far too much.

The bank itself is sturdy, it has been compacted for

many years, - I had to put in a few rustic steps and needed

to make holes for the 60mm retaining poles using a very large

 heavy breaker bar.  - It was like extremely tough going.


Gary RK said:

John, go look for/at Crib walls - I reckon that's the answer. It uses interlocking treated timber with wood beams also going into into face of slope.

This system was used at a business park we planted and was installed by clients ground workers while doing a refit and changing car park. We then installed some additional front netting and planted thru it and along the top? Don't know who supplied.

If I'm passing in next few days I'll get you a picture of how it looks after about 2 yrs.

Thinking about it more, you often see the concrete version used en masse on major roads ( but that's big boys stuff ;-)

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