Anyone here ever line a pond before? How big of a job is it? I have a couple year old pond that doesnt hold water like I'd like it to. Its not very big, like 30' by 90' and probably 4 feet deep in the middle. Looks like I can get a liner for around $1k but wanted to know if there are any tricks or anything before I start in the spring.

You'll have to seam / weld it correctly using an extruder, leister heat gun, or "mouse".

Was involved with one being lined with hypalon over 30 years ago.
Holding up well.
Know of some others done with a poly product about 10 years ago, ( hypalon got $$$) so far so.good.

Small pond, DIY, I'd maybe try these.

https://billboardtarps.com/product-category/pond-liners/

WOW, they have REALLY gone up in price too!

I don’t know why you need to seam anything just make sure you buy it big enough and cut off the extra after full.I bought the recommended underliner when I did mine.

I can't remember the name, (brain fart) but there's a common Ag product in powder form you mix in the water that stays in suspension that will gravitate to the leak and settle on the bottom that will plug the leak.

GYPSUM, I knew it would come to me!

If the pond isnt to deep, you can buy domestics or attract wild Ducks, they will stomp around and patty foot the bottom to help seal it.

Bentonite

Don't know of any HDPE that is 30' wide, so you'll have to seam two pieces together if you need that width. The 90' length isn't a problem.

It will come seem welded to the width you want. Make sure it is the real thing or turtles wiil dig through it. If your pond is below the water table you will get air bubbles under it. Buy it extra big and trim it to fit. It is heavy and aukward to handle , have plenty of help on hand.

I would try bentonite before a liner job....

Both the hypalon and poly liners I know of were field welded, but these were good sized ponds, and each roll had 6- 8 men to work.
Both had " vents" along the edges, above the water line.

I KNEW where a small pond was leaking.
Drew it down, worked a ton of bentonite into the area of the leak.
Refilled, still leaked.
Drew back down, worked in 2 more ton, into a slightly bigger area.

Leaked less, lol

A guy up here put some beef cows in the enclosure for all summer before he let water in. They stompped it down solid. To this day it does not leak that I know of

Both the hypalon and poly liners I know of were field welded, but these were good sized ponds, and each roll had 6- 8 men to work.
Both had " vents" along the edges, above the water line.[/quote]

Yeah, most liners are 60 > 80 mil and welded in the field and tested. If they're pre-welded in any large size, they are folded over several times and that is where then seams crack, weaken and split.

That's a keen idea, never thought of that but seems it would work well with the proper moisture content of the soil.
Neat !

I've heard of this also, maybe a combo of this and bentonite?

Hence, the sheepsfoot roller was born!

Personally, I would trust a factory weld over trying to get the job done in the field on uneven surfaces, weather , wind , etc. Been there and done that.

Ground prep is the first and most important first phase of laying liner. That's why very few people are certified in liner seaming, welding and testing.

The hypalon liner, 30+ years ago, was a crew from 2000 miles away, it's ALL they did.
The liners 10 years ago?
Who knows,they didn't speak a word of English, lol.

15 years ago, depending where, was HDPE or FML use. Didn't care what language they spoke . . . all the crews I worked with were A+++. :-)