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04/01/2013 at 17:03

Can anyone advise me please. We have a very steep, almost vertical, high bank at the back of our house that, with all the rain, has partially slipped (my husband has today cleared away 18 barrow loads of sand and rock). The only thing growing there at present is bramble. Ferns in other places seem to have been very effective at holding back the bank and I'd like to extend these but haven't a clue how to start. I have ferns in other places that I could split but would this be the best way to propagate them?

Has anyone out there overcome a similar problem? Any suggestions about what plants might be effective and easy to establish without disturbing the bank too much? Any advise would be very much appreciated.

05/01/2013 at 00:02

I don't think you have given enough information.  Do you need a retaining wall?  Is another land-slip going to be inconvenient or dangerous?  Ferns are not deep-rooting enough to hold much back.  Take a look at how the Highways Agency does it.  Perhaps you need to stabilise the bank with wire netting before you plant.

05/01/2013 at 05:56

Another thing to think about is how deep behind the  face of the bank is the water eroding?  18 barrowloads is a lot of landslip.  I agree with Welshonion that some sort of engineering solution might be sensible.   I think advice from a landscape architect might be needed, otherwise you'll only stabilise the bank until the next time we get a lot of rain. 

05/01/2013 at 19:19

Thank you Welshonion and Dovefromabove for your responses. I don't think a retaining wall is really practical in the situation as there just isn't the space between the house  and the bank,  I'll try to get some photos to post. I have the number of a company to call on Monday about some netting type stuff that can be planted through so I'll see what they have to say.

We're not sure where the water is causing the problem, that is how deep down. We've lived here for six years and this is the first time we've had anything as bad as this.The bank is practically a vertical sandstone cliff  with earth, bushes and brambles at the top and down much of the face of it. It's pretty inaccessible for any meaningful maintenance. The earth on the face/slope varies in depth from nothing (bare rock) to a couple of feet.  Recently there have been a number of local rockfalls brought on by the heavy rain.

It's not somewhere that is likely to cause danger at present, just hard work and inconvenience, but we would really like to prevent it getting any worse if possible.

06/01/2013 at 17:14

Carole,

How high is the bank and what's at the top of it? Is this a newish house? Are any neighbours in a similar situation?

Joe

06/01/2013 at 21:57

Hi Joe,

The house has been here for 150 years or more and the whole area for miles around is red sandstone which isn't best know for it's stability. However, this bank has been here since at least when the house was built so it can't be that bad, just problems as a result of the recent heavy rain.

I guess the rock face is about 15-20 feet high, that is from the ground floor access path at the right side of the house. Above the rockface and back a few feet is an area of woodland but immediately above the rock face is earth and a tangle of overhanging brambles that we will have to get to grips with, it just not easily accessible.

The escarpment continues behind the house to the left where it is accessed from a walkway at first floor level and is about ten feet above the walkway. Here it is covered with earth, plants and coppiced trees and bushes and this is where the earth has slipped bringing with it some deadwood, gravel and a couple of football sized boulders.

We've seen some degradable jute type membrane on the net that can be bought impregnated with grass or wild flower seeds and/or can be planted through. Have you ever used this? Also I read on a blog of someone who had inserted pieces of slate into their bank in order to support plants until they established, I thought this seemed a possibility.

We're now taking it easy and resting our aching muscles before taking on the next stage. We're thinking we will have to cut back the brambles and treat them with a systemic weedkiller before starting a replanting programme/membrane laying or whatever seems the best solution.

Onward and upward

Carole (sorry I've tried and failed to put up some pics but no joy!)

07/01/2013 at 09:54

Thanks Carole,

I think I get the picture now. It sounds as though the rockface at the back of the house is essentially stable, but at the top of it there is a less steep slope that is a weathered layer of rock and sandy subsoil. This sounds pretty normal, geologically. Many sandstone cliffs have this sort of weathered layer capping them - the result of many thousands of years of rainfall, freezing, thawing, etc. This appears to be where much of the material is being washed down from - so the presence of a few small rocks in the debris that you have cleared away doesn't indicate that the cliff is collapsing.Then, above this weathered layer there is a woodland on a more organic soil, but which still produces finer debris/soil that the heavy rain is washing down.

Have I got this right, and do you own the bank right up into the woodland?

Joe

25/01/2013 at 19:05

Hi Joe,

I thought I'd replied to your response above but mustn't have pressed the right button.

Yes you are perfectly correct in your analysis and we do own the woodland area at the back so there is no problem with access to the top except we'll have to abseil down the slope if we want to do any work on most of it.

I received a sample of some membrane that can be put down but it isn't very flexible and works out at around £200 for the minimum amount, so we plan to try to tackle it more simply. I have a list of some good ground cover plants that might help and thought I might slide a roofing slate into the bank to support them. Do you think that might work?

Alternatively we read something about 'socks' which are tubes of hessian that you fill with compost, stake them above and below along the contours to hold them in place and either seed into them or plant above the tube. This would come free as I have a roll of hessian and a sewing machine!

We have time for a bit more fireside planning to do though before the weather improves 

Thanks for your interest,

Carly ( just to confuse everyone I've changed my login name as most people seem to have a name other than their own!))

27/01/2013 at 16:16

Which direction does the cliff-face face, CC?

27/01/2013 at 16:24

My daughter lives on Jersey and most of the back gardens are like this. She has had (treated)  railway sleeper positioned vertically and horizontally at the bottom and middle of her 'cliff' and railway sleeper steps go up the middle.  This has provided two long but narrower beds which she finds much easier to plant out.

She has planted a row of lavender on the bottom border and plants such as different colours of phormiums and evergreens at the top. Between these she can plant perennials and summer bedding.   There is colour all the year round and she now finds it easy to maintain.

27/01/2013 at 20:56
Hi I have a similar problem at the back of my garden. The land behind my fence is about 15 ft lower and has gradually washed away undercutting my fence. Last summer I pegged chicken wire on the worst bits and then put new top soil in the mesh. I then planted it with burnet which i grew as plugs and threw more seed ontop for good luck. burnet has very good root system and is recommended to bind soil. Hessian would work in a similar way and you could cut small holes in it and plant through. My system has seemed to work it has all stayed put so far and we are on a very exposed hill when the rain catches the bank.
27/01/2013 at 21:01

Thanks everyone,

Joe, the cliff faces west but the house wall is about three or four feet in front of it so it is in shade for most of the day. The snow melt has brought down another couple of barrow loads and today I tried the idea of slates and roof tiles to support planting pockets but the earth covering isn't deep enough and I think I just made it more unstable. We're going to have another look at it once we have a dry spell and check out the soil depth/s. We're starting to think we need to just stabilise the top of the cliff and then let the rest of it find it's own level - it'll give my other half some excercise with the wheelbarrow 

Thanks Lizmac. your daughter's garden sounds lovely and would be a good idea for the less steep part of our slope where we need easier access for management. The bit that's causing the problems though is almost vertical and quite close to the house wall so there wouldn't be sufficient space for sleepers to go. One of our neigbours has done something similar though along a bank that is about six feet high. They have horizontal sleepers held up by vertical ones at regular spacings then a further horizontal sleeper is at ground level that has been cut to fit around the upright ones. I don't know if that makes sense but it looks great.

Trifid House, It sounds as though you have succeeded in getting somewhere with your slope. I have a long list of possible plants to use but Burnet is one I haven't come across. Which Burnet is it? I have found Salad Burnett which is described as having an invasive root system to compete with Ground Elder (which is actually what we WANT!) I have also come across Great Burnet. Some sites say it needs moisture but usually our soil is sandy and light, What conditions do you have?

Cheers, Carly

 

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