pond armor makes a spray. You dig the hole, lay some geo textile fabric, then spray the stuff on it. It is supposed to be more tear resistant than a standard liner.
Not to go further off topic but Ive been(years ago)at ramones shows in bars where there were so many people moshing the heat and sweat would begin to condense water,dripping off the ceiling and speakers.so in addition to the sweat of 300 drug crazed lunatics I was getting doused with poison great just great