I have gas under the lining of my in ground pool. It fills up every time it rains. It is not water. It is gas. The pool guys lit it as they pushed the bubble toward the wall of the pool. There was heat and smoke. The gas exploded out of the side and pushed water out of the pool and as the gas escaped it sucked the liner back to the bottom. They we watched it quickly fill back up and repeated the process. Then the pool guys ust stood around staring at my pool and said they had no idea what to do??

I don't have an answer to solve the problem without knowing where it's coming from. I see the following possibilities:

1. Decaying construction debris, backfill or vegitation
2. Ruptured gas line in vicinity
3. Methane geological pocket

"There was heat and smoke" sounds like an underground peat fire could be the issue. Decaying veggies and gas line would not create smoke but peat sure can.