Another natural swimming pond query.

[phatwa]

Hi all, I'm in the process of DIY-ing a natural swimming pool. Have already done the heavy work and removed the soil and now essentially I have a large hole.
Size wise it's 11m x 5m so fairly large.

I've spent countless hours researching all this over the past year but there's a few things I still can't get my head around. Can someone please offer some guidance?

1. Do you actually NEED to do a concrete slab at the base? I've read about some people just putting liner straight down and not doing a slab. I'm assuming this will increase the chances of the liner ripping. I live on heavy clay soil and there are trees not too far away (about 8 metres / 26 feet away) - is the risk of roots damaging the liner the reason for the concrete slab?

2. I'm running a rigid PVC pipe underneath most of the pond, which will go into the filtration area. I'll probably run an extra pipe as backup in case the other later breaks. Is it okay to run the PVC pipe into the ground *under* the concrete slab, or can it be submerged into it? I'm worried about the weight of concrete + water on top.

Thank you.

 

[GBBUDD]

do a concrete slab at the base? Slab is not a must it's more dependent on your soils. but if your a heavy clay you need to give the water a way out and avoid the liner hipo

26 feet away) - is the risk of roots damaging the liner Tree roots generally only grow as far out as the branches do.

I live on heavy clay soil i'd seriosly consider under liner drainage. It's nothing more than pipe that won't clog collapse or break under the liner. trenches might be needed or cover the whole bottom with a layer of stone and the fabric.

is it okay to run the PVC pipe into the ground *under* the concrete slab, or can it be submerged into it? best to place pvc under concrete if the concrete is not compacted well if it shifts and cracks the pvc in concrete won't do well. if i had my choice id run pipe outside of concrete . if it ever fails you only have decorations and soil to move.

ONE PLACE TO LOOK AT IS MODERN DESIGN AQUASCAPING ON YOU TUBE .
AND I PUT TOGETHER A LIST IN THIS SHOWCASE TOWARD THE MIDDLE AND END OF THE POST IT IS LONGGGGGG https://www.gardenpondforum.com/showcase/gbbudds-12-000-gallon-koi-pond-full-build-and-layout.141/

 

[phatwa]

ONE PLACE TO LOOK AT IS MODERN DESIGN AQUASCAPING ON YOU TUBE .
AND I PUT TOGETHER A LIST IN THIS SHOWCASE TOWARD THE MIDDLE AND END OF THE POST IT IS LONGGGGGG https://www.gardenpondforum.com/showcase/gbbudds-12-000-gallon-koi-pond-full-build-and-layout.141/

Thanks a lot.
Sadly the tree roots are an issue, I know this because I dug out the pond last autumn (and recently made it deeper, to 5.5ft) and exposed tree roots from a nearby large poplar tree.

Last year the tree roots that became exposed started to produce new little trees, so they're definitely active and growing. In the end I used Roundup on them as there were so many of the damn things, probably 50 or more. There's also a silver birch tree about the same distance away and though I haven't come across roots for that I'm sure there will be.

In terms of laying the pipe for the pump, if I divert that so it's not under the concrete base but beside it (or whatever type of base I do), is it fine to just bury that over with the soil? As it's the non-bendy PVC it's quite rigid, but I'm not sure if burying it 'as is' is going to provide longevity.

 

[phatwa]

PS: Love the idea of using pitcher plants. I'll probanly pinch it for my own pond. A lot of people don't realise that they're hardy to about -20C, so they'll be okay here in the UK. I've been growing them in my greenhouse for a while.

 

[Lisak1]

Last year the tree roots that became exposed started to produce new little trees,

There is a difference between exposing/unearthing roots and keeping them buried. What you did was give that tree the perfect opportunity to reproduce. Those roots won't do the same thing from 5 feet underground.

Now that's not to say they won't cause issues at some point, but MOST roots will find the path of least resistance and go around rather than through any obstacles. People worry that the tree will "know" there's water on the other side of the liner and pierce it to get to the water source. I highly doubt that. I have yet to see a pond re-build on YouTube where they exposed tree roots growing any where near a liner, let alone through one.

 

[phatwa]

There is a difference between exposing/unearthing roots and keeping them buried. What you did was give that tree the perfect opportunity to reproduce. Those roots won't do the same thing from 5 feet underground.

Now that's not to say they won't cause issues at some point, but MOST roots will find the path of least resistance and go around rather than through any obstacles. People worry that the tree will "know" there's water on the other side of the liner and pierce it to get to the water source. I highly doubt that. I have yet to see a pond re-build on YouTube where they exposed tree roots growing any where near a liner, let alone through one.

Ah, I suppose that's true.
I really don't know what base to go with. Why do people choose concrete normally, do you think? As in, what are the benefits versus a layer of sand? Ease of pouring/adding? The vast, vast majority of these in the UK seem to be sitting on a concrete slab.

 

[j.w]

@phatwa

 

[GBBUDD]

In terms of laying the pipe for the pump, if I divert that so it's not under the concrete base but beside it (or whatever type of base I do), is it fine to just bury that over with the soil? As it's the non-bendy PVC it's quite rigid, but I'm not sure if burying it 'as is' is going to provide longevity.

Like any construction if you disturb the soil compaction is a must. if you have tons of stones or sharp stones you may want to bury the pipe in sand, rocks and frost heaves can damage pipe. But yes pvc is fine to bury but i do imagine in England YOU GET A FROST LINE IF THE WATER IS FLOWING THROUGH THE PIPE USUALY NO ISSUES. IF THE WATER IS SHUT DOWN YOULL WANT TO MAKE SURE the pipe is open and no t under pressure give the ice some where to expand

 

[GBBUDD]

Tree roots can be stopped or at least slowed way down . they sell concrete on a mat that could help deflect the roots. I used a asphalt PROTECTION BOARD AND 3/4 AZEK

 

[seedsofnature]

I build recreation ponds and I have never built a slab. I would suggest installing an underdrain system using perforated pipe, gravel, and underlayment, that either daylights downhill, or goes to a sunken pit with a pump to mitigate hydrostatic pressure in the future. I do this with all large ponds I built that go below 3-4ft depending on soil.

Sand can be your best friend after compaction. Use a woven rock pad underneath the liner.

Do not put plumbing underneath the pond. Even your jet system should skirt the outside edge, bulkhead at the top 1' of the liner.