Hi all,
Hope i can get some help on this one!
I am currently digging out for a new pond but as my garden is on quite a steep gradient i have to retain around 10' of clay
I would like to use the retaining wall as the back wall of the pond but I'm a little worried that the weight of the clay may cause movement and cause trouble, even if i use 9" hollows with re-bars and concrete back fill
What are your views on this
Cheers Alan
I posed a similar question on another website when I was considering a similar site for a pond. The received wisdom was that generally it is best practice to have a separate retaining wall. It was also suggested that to make best use of space that if the gap between the retaining wall and the pond can be made sufficiently wide, this would create an ideal space for a filter house or bunker.
To be on the safe side, it would definitely be a good idea to consult a structural engineer.
Your killer is the clay. As the clay dries out it will give you shrinkage and movement. The las thing you want is for your end wall with the pressure on it to move. Another soloution would be to build you wall and then return some of the soil/clay to the outside of the wall to also act as a retainer. But as I suggested before consult a Structual Engineer and explain what you want to do. Far cheaper route than building it and having a failure. Expect to pay around three hundred pounds for a consultation and report. Best 300.00 quid ever spent.
You have probably thought of this already but I thought I'd mention it. It would be a good idea for the pond to either be partially raised (at least 1 foot) or to have a good drainage system between the retaining wall and the pond. Rainwater runoff will cause you all sorts of problems otherwise.
Jules,
A structural engineer at around £300 for piece of mind is well worth it
Jon,
I intend to have a raised pond of around 2'6" - 3' but i have around 3' of clay above my finished pond level so with the 3' below ground level about 9'-10' of soil (clay) to retain
I have attached a photo so you can see the problem
i intend to dig a further 2' down in the hole in the centre of the pic and the slabs will be ground level, pond to be approx 2'6"- 3' above this
What's on top of the bank? If it's a house you need to get some support on that bank sharp. If not pray we don't get too much rain. Sights like this make my heart race both for the challenge and the potential for things to go wrong
It looks to me like it will require a reasonably substantial bit of civil engineering to hold that lot back! I think this is definitely a job for a pro. I would also consult the structural engineer about the concrete pad for the pond. I think it will need to be slightly more substantial than otherwise because of the clay.
My only experience of something similar has been dealing with subsidence when I had a house located on the side of hill with a substrate of London clay. You might need a thicker base with more reinforcement.
No question about it yo are looking at a min £20k spend just to stabalise that bank. If yo have a colapse on that bank it will go to your building and then create even more of a problem. This is a job that needs serious attention before more rain gives you worse problems.
What was there before? Was there a wall or did the ban come futher down the property? Before and after ictures would hel and I wuld suggest you email to the structual engineer when you seak to him too as this is a case of very high importance. The potential for a major structual failure of the bank is very high in my opinion there is to much unsupported soil. Sory to add to your problems. Where are you?
Jules,
there was a small wall there originally but was more decorative than retaining
if you look at the previous pics you can see where i dug out for the garage, and built a retaining wall, i was hoping to do a similar job for the pool
this is the only pic that may give you an idea of the gradient of the garden originally
im in Telford in Shropshire
cheers Alan
right we may be ok here but you have got to pull your finger out. You need to dig down lay some foundations with steel re-bar coming out of the foundations for you to lay 9 inch hollow blocks over. this will be the cheaper way of doing it. From the previous pictures you can se how the sil was supoted by the gradual fall of thegarden toward the property. You have taken this support away and need to block up as a minimum to stop the bank collapsing. The engineers route will probably lay a concrete foundation with steel re-enforcing coming up the bank. You would then pobably have concrete cast between shuttering and then it would be safe to build your pool. All this is a common sense approach on the safe side but I advise you to seek help from a structual engineer. Good luck and start saving.
Jules,
Thanks for your help with this
i will get some foundations in with re bars and get it blocked up and concrete back fill this will then support the soil then i can get a bit of advice on the pond build
When you have done this you also need to add some form of drainage behind the wall to run out by the garage for example. You could then use the wall as part of the back wall for your pool. Why don't you call me tomorrow?
