I used 40 mil HDPE. 60 mil was an option at almost double the cost. 40 is thick and I don't see it wearing out anytime soon. Lots of the oilfield frac ponds are built with 20 or 30 mil. The best way I can describe this liner material is it is like the plastic that a quart of oil container is made out of our the material 3 ring binders are made of. It isn't rubbery or flexible it is pretty stiff and durable.

Yes they use a skid steer with a big attachment to lay the material out it comes in rolls maybe 20' wide and then they have a fuser machine that welds the pieces together.

I didn't have any rocks to worry about but if you do they can lay a geotextile fabric under the liner to protect it at an added cost.

My pond is between 1/3 and 1/2 acre (measured by survey grade GPS) and they installed mine in a day and a half.

The guy's contact information is Cale Sanders 806-470-8098. Tell him you got his number from Brandon in Lubbock and he will treat you right. The other bid I got was from Big D and they have a very good reputation in the liner business (I work in the oilfield) but they were nearly double the cost. Cale did my pond and one for my neighbor that was heart shaped and around 2 acres I think.