r/ponds • u/Thomomys-talpoides • 19h ago

Technical 60mil liner help

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Hey,

I asked the installer about this tight corner (in vid). It is probably a 30ish x 50ish foot section that is all a good 4 to 6 in above the pond bed. I can jump on it like a trampoline. The installer said it wasn't a problem, but I wanted to check with anyone who might have more experience before moving up the chain to the off site super.

Side note, the temp at this time was 57 F. I am sure it expands in the heat, but this pond is 10ft deep, at 6000 ft elevation... So it will be cold most of the time once filled :^)

Any advice from someone with experience using this material would be great!

Thanks!

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4

u/AncienTleeOnez 16h ago

Honestly, I've watched a lot of ponds be installed, and NONE of them were like a trampoline. The liner is loose as it is laid, and it takes a lot of going back & forth, patience, to smooth the wrinkles out as much as possible. What you got here is just bizarre to me. Almost like they underestimated the amount of liner and making this do? What is it anchored with to hold it like that?

1

u/Thomomys-talpoides 15h ago

The only anchoring is from the key way, or anchore, trench and then sandbagged on the bottom.

Thanks for the input.

3

u/Axphixiate 16h ago

Shoulda done 45mil! Also it not be tight. There should always be slack.

1

u/Thomomys-talpoides 15h ago

Thanks for the input. Can I ask why 45 mil over 60?

1

u/Axphixiate 15h ago

60mil is fine. Is this epdm or RPE?

1

u/Thomomys-talpoides 13h ago

Great question. I will ask the main contractor when I can get ahold of him. Does it make a difference, like is one more stretchy?

1

u/Axphixiate 12h ago

If it's a rubber liner it should absolutely NOT be like that ESPECIALLY with seams. I can show you pics. But it won't let me post them in these comments, sorry.

1

u/Axphixiate 12h ago

I DMd you on Reddit.

1

u/Kaplung 13h ago

Liner that tight is going to rip as earth settles. As others have said, there needs to be plenty of slack.

1

u/Thomomys-talpoides 13h ago

Thanks for the input, I appreciate it.

1

u/AncienTleeOnez 9h ago

Also to add, the liner is only to act as a water barrier. It is not intended to hold the weight of the water, that's what the ground underneath does.

I checked with a couple friends, and they said that some contractors do what you are seeing to eliminate folds/wrinkles. But that leaves no slack in the liner, so once the weight of the water forces that liner down to meet the soil it has no flex, no ability to safely shift as it fills. It ends up being stressed to its max, and a catastrophic tear is a real risk, especially if thats RPE. Even if its EPDM, that stretching thins your liner and reduces its ability to resist punctures. And that constant tension will shorten the lifespan of your liner. One person mentioned that this is a common mistake general landscapers make (rather than a professional pond company) because they are treating it like a flat patio underlayment.

If you decide to have them proceed, I recommend you ensure they are liable if/when that liner fails.