Bulging water under liner HELP !!!

[beetroot]

I'm getting on in age 66yrs but fairly sprightly and like doing all my own jobs in garden. Ive always wanted a pond, so decided to give it a try before I'm to old lol. So tried a small one February, last year about 18 inches deep and 6 feet wide. Only place I could put it was at bottom of garden and the garden slopes down a bit, so water runs down the garden when we have loads of rain. I put several sheets weed fabric down over the soil, then the liner. Bought a UV lamp with pump, it was brilliant, looked great with the plants but NO fish, I loved it, was soo clear the water. Then this last winter when we had loads rain, my liner started to bulge up into the pond. I checked it, it is water definitely under the liner, at the bottom and the sides. I put loads stones in it to keep it down for now but don't want loads stones all over the bottom and sides takes up so much space. Also it can collect lots debris as I have no fish In it. Im desperate to sort out, someone must of had this problem before. P!ease help

 

[Lisak1]

Welcome to the GPF!

You've got a hippo! That's what it's called when you get water under the liner. Essentially you need to do two things: 1. get the water out and 2. fix the issue so it won't happen again.

Someone here will have a solution for getting the water out - I'm thinking you could get a portable pump and snake a hose under the liner, but that will depend on a lot of circumstances I suppose.

As for prevention - you need a berm around the pond to keep the water from being able to flow under the liner. Lots of info on this forum on the proper way to edge a pond to keep runoff from entering. (Also I know you said this was the only place you could put your pond, but this is the reason why it's not recommended to use your yard's lowest spot. )

 

[TheFishGuy]

Great advice above, I know a few people here have had that happen, so we will wait till they arrive. After you have the problem solved you can dig a little "trench" around the pond, and put the edges of the liner in that so that was flows into the pond rather than under it. ( still not ideal to have runoff going into the pond, but if there are no fish it shouldn't be a big deal )

 

[beetroot]

Welcome to the GPF!

You've got a hippo! That's what it's called when you get water under the liner. Essentially you need to do two things: 1. get the water out and 2. fix the issue so it won't happen again.

Someone here will have a solution for getting the water out - I'm thinking you could get a portable pump and snake a hose under the liner, but that will depend on a lot of circumstances I suppose.

As for prevention - you need a berm around the pond to keep the water from being able to flow under the liner. Lots of info on this forum on the proper way to edge a pond to keep runoff from entering. (Also I know you said this was the only place you could put your pond, but this is the reason why it's not recommended to use your yard's lowest spot. )

Thank you for that. Just to say my pond is on the highest part not the bottom of the garden, think other people's gardens around me are higher than mine, so they drain into mine!! Will a berm help? Wont the water simply run along under the ground down to the pond liner, not necessarily always run along the top of the soil? Thanks

 

[Mmathis]

Hello and welcome!

To combat my water hippos, I raised the edges of the pond so that water level was always at or above ground level. I was fortunate to have enough liner that I could do this. Others have dug trenches down below the liner and used sump pumps to draw the water out. It’s all about hydrostatic pressure, so until you can stop the water from getting under the liner, the problem won’t go away.

 

[j.w]

@beetroot

No hippo's here at my pond but all good advice above

 

[Toluca]

I don't have personal experience with this as my pond isn't built yet but my yard gets extremely wet so the contractor I'm working with said he will install a liner air vent to prevent " water hippos". Might be something to look into.

 

[GBBUDD]

The bulge your getting is as you suspect more than likely water under the liner and at 18" deep there's not a hole heck of a lot of down pressure on your liner from the weight of the water inside the pond. So as water gets under the liner the easiest place for it to go is to lift into almost a neutral space being water below the liner and water above the liner and i 'll venture to guess that you do not have any stone in the bottom of the pond. The is an easy fix as you have a 18" deep pond and that is to get out the garden shovel with the long handle it's a shovel that's almost a third the size of your standard shovel and dig down next to the pond as you dig you should start hitting water. if you can get close to the liner and dig down about to a depth of 24 inches fill in the bottom 4 inches with some rock and then insert two pieces og garden hose to the bottom of the pit to the rock and then finish filling in the hole with rock what your doing is giving the water an easier way out and up . try to do this in the lowest area of the pond so water can drain away from your hose.

Then like was mentioned above you want to make sure run off from rain events are not getting in your pond . if you can stop this easily it may be your first alternative . stop the water from getting under the pond may stop the hippo

 

[Marck]

Greetings, welcome to the Forum.

One possible solution is to weigh down the liner with large flagstones or something similar. Place them gently of course, so they don't damage the liner. If the water pressure from below was very high it could lift the flagstones too, but I don't think that would be the case in most situations. The liner probably lifts up because it is flexible, not because the water pressure is high.

 

[GBBUDD]

In extreme cases @mark YOUR CORRECT IT CAN NOT ONLY LIFT A FLAG STONE IT CAN LIFT THE ENTIRE POOL and i'm talking a concrete pool. thats is why todays pools have a PETCOCK sorta speak in the bottom of the pool so when the Water BUILDS under the pool the plug blows instead of lifting the entire pool. look it up,,,,,
But you could be right they could also have a pocket of gas trying to get out that's directly below there pond but That is most certainly not the average. 99% of the time it is water build up below the liner.

 

[addy1]

My pond is at the bottom of our steep slope. On the up slope side of the pond I built a 2 inch berm so any water that ran down the slope goes around the pond. With vegetation, rocks etc on the up slope side you don't even see it.

During every hard rain, while I was building, I went out with a umbrella and watched the water flowing down the slope to see which way it went. I kept working on the berm until it went around the pond.

Welcome to the forum!

 

[brokensword]

During every hard rain, while I was building, I went out with a umbrella and watched the water flowing

it's ALL TRUE! Even got video evidence (well, pics, actually; sowwy, Castle rulz; no vids in posts that are unauthorized by the muckety mucks!);

 

[addy1]

it's ALL TRUE! Even got video evidence (well, pics, actually; sowwy, Castle rulz; no vids in posts that are unauthorized by the muckety mucks!);

View attachment 147074

Well never went out during thunderstorms and usually in flip flops..............................

 

[brokensword]

Well never went out during thunderstorms and usually in flip flops..............................

ya know, I shoulda remembered that...sheesh, am slipping...too late to doctorfind another incriminating photo...you SURE you don't own lil white rubber boots? I DID see something like that on the last Restocking Requisition that crossed my desk...and yeah, I found a desk, not like it didn't take some effort; who hides office furniture under a load of bee keeping equipment???? I ask ya, who???

 

[addy1]

WELLLLLLLLLLLLLL to be honest I did have some white rubber boots, let them go with the searay when we sold it way to big! And I wear hardly ever wear skirts..................do better doctoring next times.............

But it sure worked to see the water flow down our slope when it poured............. The slope above the pond is 25 degrees.
Water poured down it. You need to see the path to get it to divert the way you want it to.