This case history is of a repair on an existing liner where methane had created a large bubble underneath the liner.
The reason why methane was building underneath the liner, was because the contractor had to build the pond over organic materials that could not be removed. These decaying organic materials were creating methane as a by-product. As the methane built up, bubbles in the liner were created. The original wick drain installation in this pond was done in a parallel pattern not a grid pattern, where two slopes were not covered by wick drain. It was the unprotected slope that ended up having bubbles.
Solution: Install a Titan Wick Vapour Drain. The trenches had to be hand dug before the installation of this drain.