Flood causing pond damage?

[Panda]

We have a large (150,000l) garden pond with an old liner which we inherited when we bought the house 10 years ago. We live on a hill in Somerset and experienced particularly heavy rain over the last 24 hours. We have never experienced flooding before but on this occasion the liner of the pond has grown a large above surface bubble and in places it has been pushed off the bottom of the pond to within a few inches of the surface. The water table has clearly risen significantly as a well in the garden is overflowing. What should we do to restore the pond? Should we push the bubble down as the water recedes? Should we try to push down the rest of the liner?
There was also a small amount of air bubbling in the water near the bubble in the liner when it first started forming - I presume this is a leak in the liner, not helped by the pressure of the water coming up from underneath. The bubbling isn't obvious now, but as the water levels return to normal, any suggestions of what we should do?

 

[hamstermann]

Is the liner in your pond bare? Maybe you could force it down with some rocks.

 

[j.w]

@Panda
Darn this thing happening to you is called a "Hippo" and has happened to people here who can tell you ways to get rid of that water under your liner. I've never had one, we have very sandy soil. You may have to dig from the side at a lower level than your pond bottom to allow the water to run out from underneath. Like a tunnel. You may have to install some kind of a tube, pipe so when this happens again the water has somewhere to flow. For now I will just let someone else tell you more.

 

[Panda]

Is the liner in your pond bare? Maybe you could force it down with some rocks.

Yes, the liner is above the surface, and bare/without gravel etc.

 

[Panda]

View attachment 161484 @Panda
Darn this thing happening to you is called a "Hippo" and has happened to people here who can tell you ways to get rid of that water under your liner. I've never had one, we have very sandy soil. You may have to dig from the side at a lower level than your pond bottom to allow the water to run out from underneath. Like a tunnel. You may have to install some kind of a tube, pipe so when this happens again the water has somewhere to flow. For now I will just let someone else tell you more.

Thank you - yes , looks like a hippo! Need to let the air out and also wait for the water table to drop.

 

[WaterGardener]

It is water under the liner, not air. As @j.w. said, you need to find a way to drain that water under the liner.

You can dig a trench around the sides of your pond that are along the hill. This will divert the water away from the pond. Our pond is built into a hill, too, and even though we built the pond so that rain would run away from it, we had to do this to keep those very heavy rains from running into and under the pond.

 

[GBBUDD]

It can be an easy fix or it maybe a battle its all in how you can recognize the weak point. Water talks the path of least resistance. So your liner that was holding water above started to see water build up below. The pressure from below became more than the water above thus forcing the liner up. Often it can be a mix of water and air after all water is h20.
So what's the fix . The fix is to provide a path of least resistance. Give the water a new way to get out f r om under your liner. A couple empty pipes can do the job. But be careful they can also cut your liner. You need to get them to the point that the water finds the empty pipe and will rise in the pipe instead of your liner. Good luck

 

[casper324]

You need a pump out pit

 

[addy1]

Welcome to the forum,

Like said above get that water out from below the liner.

 

[Panda]

Thank you everyone for your advice. I think the pond liner sits on a clay base and now the water table is reducing, so is the level of the pond and the liner is sinking back down. The 'hippo' has disappeared but I'm not sure how we prevent it from happening again. There is no obvious way of preventing the water table from rising so dramatically! It has never even been close to happening in the 10 years we have lived in the house.

 

[j.w]

Thank you everyone for your advice. I think the pond liner sits on a clay base and now the water table is reducing, so is the level of the pond and the liner is sinking back down. The 'hippo' has disappeared but I'm not sure how we prevent it from happening again. There is no obvious way of preventing the water table from rising so dramatically! It has never even been close to happening in the 10 years we have lived in the house.

I have read where they say building a berm of dirt around your pond w/the liner over the top of it helps this. Not sure how this works tho. They say it diverts the water away from the pond liner underneath and send the water away from the pond instead of straight down the sides along the liner.

 

[GBBUDD]

SAME ANSWER

 

[WaterGardener]

We dug the trench and mounded up the soil we dug out on the side of the trench toward the pond. Haven't had a problem since we did that several years ago. It keeps the water from going down the hill to the pond and under the liner.

The trench is 6 to 10 feet away from the pond itself, and on the 3 sides of the pond that are cut into the hill. Now all the rain drains away from the pond.

 

[sissy]

My neighbor haas had to put a sump pump down inside the liner of his pond . He added sand after that and a water fall bulid to divert the water that runs down the hill in heavy rains . It has worked so far . He had the never had a problem with the pond until a couple of years ago , He built a huge work shop n his property and I think he may have accidently diverted the run off . The pond was there when he bought the house and I showed him picks of it before and he can see the new workshop may be the big problem . So he built the waterfall . It is dry most times until we get heavy rain and then water runs down the waterfall .