Pool build - high water table - do I need to seal and what to use?

[Lamby2244]

Hello - I am new here so please be gentle I am also new to pools. We decided that because our son is not so great on land (because of Dyspraxia) we'd build him a pool. He loves water.

After MANY quotes a very well recommended pool builder said he would do our job - I heard from and saw his previous builds so that was super good.

We discovered after digging that we have a high water table and we had loads of cave ins which our incredible builder took in his stride in terrible weather. We have now got the structure finished and its all back filled with pea shingle and we have a drain/sump built on the edge which will be accessible from the surround if we get build up.

The issue is that the ground water is still flowing as it does and the pool area never dries. Is this an issue? I was worrying about the liner bubbling up later potentially. Is there a way to seal the pool or is it not needed because the water pressure from the pool will mean this is never an issue?

Help please! Thanks

 

[Texas Splash]

Welcome to TFP! For your question about ground water seeping upwards under the new liner, I'm going to tag @jimmythegreek for his thoughts. Standby, and thanks for posting.

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[Lamby2244]

AMAZING THANKS.

 

[Jimrahbe]

L,

If you are worried about your liner floating, you need to talk with your pool builder about "well points".. These allow you to pump ground water out after the pool is built.

I suspect your pool builder is already going to use them, but follow up with him to make sure.

Sealing of any kind will not help at all.

Thanks,

Jim R.

 

[Lamby2244]

L,

If you are worried about your liner floating, you need to talk with your pool builder about "well points".. These allow you to pump ground water out after the pool is built.

I suspect your pool builder is already going to use them, but follow up with him to make sure.

Sealing of any kind will not help at all.

Thanks,

Jim R.

By this do you mean something like a sump? the builder has put one 300mm pipe to 2' below bottom of pool. would you do multiple?

 

[JamesW]

By this do you mean something like a sump? the builder has put one 300mm pipe to 2' below bottom of pool. would you do multiple?

Is water building up in the pipe?

Are you keeping it pumped out?

If one tube is not controlling the water, then you should add more tubes at different places until the water is controlled.

You can do well points instead of tubes if you prefer, but you would need to be able to connect a pump to the well points.

The tubes are better because you can look into the tubes to see the ground water level.

 

[Lamby2244]

Is water building up in the pipe?

Are you keeping it pumped out?

If one tube is not controlling the water, then you should add more tubes at different places until the water is controlled.

You can do well points instead of tubes if you prefer, but you would need to be able to connect a pump to the well points.

The tubes are better because you can look into the tubes to see the ground water level.

We haven’t got the liner in yet. I am thinking about what I can do before I put it in. The sump is not filling up. The water comes in about 12’ from the pool floor. The water will be nearly 5ft deep. Thanks for the videos!

 

[JamesW]

The area needs rock to allow the water to move and not build up.

The tube has to be designed and installed correctly to allow water to get into the tube.

If you're getting weeping through the walls and no water in the tube, then you probably have a design problem that needs to be addressed by a qualified expert.

 

[JamesW]

Do you have a picture of the tube?

 

[Lamby2244]

Do you have a picture of the tube?

I will take one tomorrow. All of the walls are backed by pea shingle and the tube has gravel in the bottom. The water I likely coming through the walls because there is nothing in the way yet I.e. the pool is not complete.

 

[Lamby2244]

Do you have a picture of the tube?

 

[JamesW]

If there is no water in the tube, it might be due to the backfill material not allowing the water to migrate to the tube or the wall might just be especially porous.

Did they hit water during the dig?

If yes, at what depth?

You can try adding a second tube if you think that you are getting excessive ground water buildup.

Are you near any bodies of water?

If yes, what is the elevation of the surface of the water in relation to the pool?

 

[jimmythegreek]

Before they added the pea fill they should have laid drain pipe amd pitched it slightly around the pool back into that standpipe. That pipe surrounded by gravels would have caught all the ground water. It's likely that when liner and water go in the resistance will push water to the open cavity of the pipe, hopefully its perforated and surrounded by gravel

 

[Lamby2244]

Before they added the pea fill they should have laid drain pipe amd pitched it slightly around the pool back into that standpipe. That pipe surrounded by gravels would have caught all the ground water. It's likely that when liner and water go in the resistance will push water to the open cavity of the pipe, hopefully its perforated and surrounded by gravel

Thank you for validating my thinking. The water won’t be in the pipe yet as there is no liner full of water in the way of the ground water. The pool walls are surrounded by at least 1.5ft of pea shingle as we had a lot of cave ins so that seems good.

I don’t know about the drain so will check.

What I realise now is that the back pressure of the liner filled will disperse the water and hopefully the system works. I also learned that this is very common in the Uk and that my ground water issue is mild compared to some who have still built a pool.

thanks for your comments.

 

[jimmythegreek]

If the ground percs water it will find it's way slowly. If its clay type material it likely will not. I build in heavy clay regularly, most of my builds have sump systems with powered pumps. I have 3 on my personal pool where nobody with common sense would have built a pool, but I love a challenge