Vacancy under leak

[AndyT86]

I found a leak in my pool. It is about 4 inches from the steps on the floor of the shallow end. I think it has leaked for a couple of months, and now there is a soft dent around it. The "dent" is about 3x5 inches and about 1 inch deep. This is with less than a foot of water in the shallow end. (15x30 In-Ground) I'm not sure if this is the size of the area washed away, or if this is just as far as the vinyl is stretching.

I have not repaired the leak yet, as I am not sure if there is something I should do to fill the cavity that has apparently been formed by the dirt being washed away beneath the liner. Currently all I have done is place a plastic sandbag over the hole to stop the water flow. My wife said I might regret refilling the pool before I find out how to deal with the cavity, because I would have to let it out again if I have to pull the liner away to repair the area below.

The hole is only about a quarter inch long, so it does not seem practical to try to get sand under the liner through the leak.

Anybody got any ideas, or have any experience with this type of situation?

Thanks

[CanuckPool]

Correct me if I am wrong, but isnt there a 4" layer of concrete and a cement skim coat on top of that and then the liner? Your liner is placed right on top of dirt?

[AndyT86]

When it was being built, they put something in that the builder called "Pool-Lite". He described it as concrete mixed with vermiculite. So it's like these little styrofoam beads in a cement mixture. The walls also have a blue padding about 1/8 inch thick to pad between the wood wall and the vinyl.

I was not around when they poured, so I'm not sure how thick the pool-lite is on the bottom. And unfortunatley the pool builder has gone out of business (maybe because of poor workmanship?).

I know the deck around the pool is four inches thick, and we have had some problems with it settling since it was built seven years ago. We even had to replace a section of the deck the second year. I don't think the ground was properly tamped before they poured the deck. Could they have cut corners on the pool itself? I can't imagine the pool settling so much that it leaves a gap this large in the concrete.

My pool is in west central Georgia. My cousin's pool in south central Alabama was built about 30 years ago and it seems to have sand below the vinyl. You can feel it give under your feet when you walk in their pool. Maybe the code was different back then?

I was thinking that maybe something like a caulk gun could inject some material through the hole in the liner to fill the void under there. Any suggestions on what that material should be? This is starting to bother me.

[CanuckPool]

I know there is caulking you can use to seal your rain gutters when they are leaking, and you can use it underwater, maybe you can try that.

[AndyT86]

A friend who used the same PB reminded me that the Pool-Lite was dumped out in dry powder form, then they sprayed water over it to "damp set" it. So apparently it was not a concrete pour.

I'll check into that gutter caulk. I know it can be applied wet, but do you think it will cure without exposure to air?