Landscape Industry Forum

Advice for dealing with a very steep bank.

 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.

You need to be a member of Landscape Juice Network to add comments!

Join Landscape Juice Network

Email me when people reply –

Replies

  • 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.

      

     

    BonTerra (KCN4 / KCN7) Special Solutions Blankets

    BonTerra KCN4 or KCN7 Special Solutions Blankets are manufactured from a matrix of 100 per cent untreated coir fibre (approximately 300 grams per square metre) evenly distributed and stitched on the upper side to either a 400 or 700 grams per square metre coir mesh and to the lower side, with either a Polypropylene or biodegradable jute mesh, or a second 400g/sqm or 700g/sqm coir mesh. The stitching thread is synthetic. These Special Solutions Blankets are available in either unseeded or pre-seeded versions.


    Special Solutions Blanket

     

    Recommended Application

    These high strength blankets are suitable for extreme erosion conditions such as stabilising lake shores, river banks, areas beneath water outlets, or ski slopes. They provide long term soil protection and help establish protective vegetation.

    Durability

    3 – 5 years - depending on the prevailing conditions, including the location, temperature, moisture availability and the soil acidity.

     

     

     

     

     

    Weight

    Material weights range from 700g/sqm to 1800g/sqm. The standard roll size is 2 x 25m.

    General

    KCN4 and KCN7 are manufactured to specification. Technical data are available upon request.

     

     

    Installation

     

     

    BonTerra KCN4 and KCN7 Erosion Control Blankets should be installed with the coir mesh positioned on the upper side and should be securely pinned with 300mm mild steel pins, at a rate of 3 to 4 pins per square metre, to ensure one hundred per cent ground contact.

    Comprehensive installation guidance is available upon request.

     

     

     

    BonTerra Blankets are manufactured in accordance with the ISO 9001 quality system management.

     

     

     

  • 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?

This reply was deleted.

LJN Sponsor

Sponsors