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Thread: Sleeper pond wall collapsing
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03-01-2022, 07:55 PM #1
Sleeper pond wall collapsing
I have a sleeper pond built on a concrete collar the pond is dug down past the collar. Somehow the ground on one side is being pushed outwards by the liner. Bizarre as the concrete hasn’t moved an inch and it’s all still dead level. Been pushed in a good 5/6” so need to take action as soon as before the liner is damaged. It’s only 1/1.5ft below ground level so would I be able to drain the water to relieve the pressure and dig up that small area to fill with either sand or concrete? Not sure what the best option is as have never dealt with anything like this before. Any help would be greatly appreciated.
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03-01-2022, 07:57 PM #25000 Gallon Fibreglassed Pond With 54" x 27" Infinity Window
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03-01-2022, 08:06 PM #3
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03-01-2022, 08:38 PM #4
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RS2OOO Thanked / Liked this Post
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03-01-2022, 08:54 PM #5
Hi
If I understand the situation an area of the sleepers have moved to create a slot that the water is now forcing the liner into the slot. If you can access the area from the outside I would try and use a jack and some wood and push the sleeper back into place, You might then be able to use "L" brackets or screws at an angle to secure the sleeper in place. When I made my 1st pond from sleepers I used rods vertical up through the sleepers from the cement collar - this was a lot of work
KevT
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03-01-2022, 09:06 PM #6
Hi,
sorry should have explained better. The sleepers haven’t moved at all it’s the ground bellow them which is really odd. I can access that side and wouldn’t have to dig down far at all just wondered what the best way that fill it was.
Thanks
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03-01-2022, 09:13 PM #7
Its difficult to say from the picture but it looks like the sleepers below ground could have rotted, I am assuming the bit that has pushed in is below ground and below the concrete collar, I know most modern sleepers are from wood that grows quite fast and has a tendency to rot very quickly even though it is pressure treated, I have had some before that weighed twice the weight or others as some were soaked in water from the saw mill.
I don't think you have much option with regards to draining the pond, I would say its your only option, only then will you be able to determine what has happened, I could be that there was a fill in piece below ground that has moved or it could have rotted away, either way it needs to be addressed as you say.
You could drain the pond partially and slip some ply between the liner and the sleepers to relieve the pressure and then dig from the outside and fill in with concrete
A picture of the outside of the pond might help and also what depth is the bit that has pushed out, in relation to the ground level.4600 Gallon Concrete Block and Fiberglass
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Ajm, reecehailey7 Thanked / Liked this Post
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03-01-2022, 09:20 PM #8
If that is just below the collar it could be that ground water has eroded below the collar enough to weaken in and that would give the mass of water in the pond the opportunity to push it underneath the collar, this is actually what happens when capped off mine shafts collapse, its the action of the ground water eroding under the slab causing a weak point
Lower the pond water before you dig down and then dig out and fill with concrete, make sure its gone off before you refill the pond4600 Gallon Concrete Block and Fiberglass
2100 mm x 710 mm Infinity Window 32mm thick glass
2 x Aerated Bottom Drains and Skimmer
Filtreau HiFlow 30 Drum Filter
Bio Chamber - 140 litres K1
Bakki Shower - 30 KG Sakura Far Infrared Media
2 x 18,000 lh pumps
Heated from house boiler through a heat exchanger
Idealseal MS290
My Pond Build
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reecehailey7 Thanked / Liked this Post
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03-01-2022, 09:27 PM #9
the ground must be very soft for it to give way like that under the collar.
did you dig down to solid sub soil or did you lay the collar on to brown earth?
as for fixing, if it's only that spot that is soft.
like uncompacted earth you back filled for the bottom drain trench.
then you could empty the pond below that level, carefully dig out the soft earth
support the liner side with a sheet of ply or osb to keep it flat, and stop it bulging the other way when you back fill.
and back fill with something more solid, like concrete or post mix.Last edited by davethefish1; 03-01-2022 at 09:31 PM.
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RoyLittle0, reecehailey7 Thanked / Liked this Post
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03-01-2022, 09:33 PM #104600 Gallon Concrete Block and Fiberglass
2100 mm x 710 mm Infinity Window 32mm thick glass
2 x Aerated Bottom Drains and Skimmer
Filtreau HiFlow 30 Drum Filter
Bio Chamber - 140 litres K1
Bakki Shower - 30 KG Sakura Far Infrared Media
2 x 18,000 lh pumps
Heated from house boiler through a heat exchanger
Idealseal MS290
My Pond Build
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03-01-2022, 09:38 PM #11
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03-01-2022, 09:41 PM #12
Don’t think I have much of a choice but to lower it and dig down now. Always something with ponds… sleepers look good it’s jut let under the collar. Have had a crazy amount of rain recently so somethings given way. Just glad the pond itself hasn’t moved! So everyone is in agreement concrete is my best option to fill in the void? At least this has happened now before I start stocking again.
Thanks everyone
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RoyLittle0 Thanked / Liked this Post
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03-01-2022, 09:43 PM #13
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RoyLittle0 Thanked / Liked this Post
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03-01-2022, 09:48 PM #14
As Dave suggests, Postcrete might be the best option as it sets in 5 t o10 minutes so you can drain and refill in a day.
Water erosion under concrete is more common than you might think, I worked on call outs for RJB mining looking at potential mine shaft capping's collapsing and it was always due to water erosion
Best of luck and keep us informed as to how you get on.4600 Gallon Concrete Block and Fiberglass
2100 mm x 710 mm Infinity Window 32mm thick glass
2 x Aerated Bottom Drains and Skimmer
Filtreau HiFlow 30 Drum Filter
Bio Chamber - 140 litres K1
Bakki Shower - 30 KG Sakura Far Infrared Media
2 x 18,000 lh pumps
Heated from house boiler through a heat exchanger
Idealseal MS290
My Pond Build
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reecehailey7 Thanked / Liked this Post
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03-01-2022, 10:00 PM #15
I can’t say I’ve heard of it happening before. Could have been a lot worse though as it’s only in a small spot.
I’ll grab some this weekend and fingers crossed it doesn’t rain so I can get it sorted! Thanks for the help and I will let you know how I get on then I’ll be asking where to get some nice koi from haha.
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RoyLittle0 Thanked / Liked this Post
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06-01-2022, 06:23 PM #16
A similar but far less noticeable thing has happened with my sleeper pond.
One side of pond is about 8" from garden fence which has concrete posts going about 18" deep, and the fence post behind pond has moved into next doors side by about 4".
Dave's suggestion about a possible leak is worth investigating when you dig down even if there's no other signs of a leak.
What you could do is peel back liner, get some 1m scaffold poles and sledge hammer them down, then put some OSB board (maybe treat it first to slow down rotting) between the poles and liner, then back fill with as much concrete as you can get down there. That should keep things going for another 5 to 10 years and should be a relatively quick and easy solution that saves too much digging and disruption.
Try to collect as much pond water in paddling pools etc (borrow from family but don't tell them what for), then you can refill pond nice and quickly once concrete set.
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06-01-2022, 08:36 PM #17
Could it possibly be a leak which is washing away the soil underneath causing the wood to sink?
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22-01-2022, 04:11 PM #18
Finally the rain held off for a week so upon inspection something has been digging under the decking and through to the pond. Found a nice little tunnel. No idea what’s done it but it’s not small either way! Had to fix the best I could and fill with concrete. No longer pushing out but I do have a slight bulge coming into the pond now. Will work for now. If I decide to stay where I am (will know in the next year or two) I will dig down and brick the lower part and fibreglass the lot. Might even add a second window! Thanks for all the help
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