I am new to this forum but have a thread going about my own leaky pond. Having our own 1/10 acre pond six feet deep, my own two cents is to do anything you can to get the clay layer right. We did bucket tests in which we drilled holes in the bottom of a five gallon bucket, filled it most of the way with the clay we were going to use, covered the clay with water, and then put it where it would see little evaporation. The goal was to see how well it held water or if it leaked out the bottom.
We had good clay by that and the experts' analysis, but I think the guys who put down the clay liner were not experienced with what they were doing (I wasn't either!). I believe esshup suggested an 18 inch thick liner; ours was only 12 inches. I am not sure how to do that accurately, even on a small pond like yours and mine. Anyone have a way to know?
Our guys used their excavator tracks and bucket to compact the clay. I'd go for the sheepsfoot if possible. I don't know about a roller, but using a bucket did not do the trick. Our pond has been leaking for ten years, and we've spent a ton trying to fix it.
Go for the sheepsfoot and as much good clay as you can. Remember not all clay is equal and it is also worth trying to make sure the clay will hold well. For a pond that size you can consider mixing in some bentonite or ESS-13 right from the start if your clay needs it.
