you have a challenge the liners only work if it covers the entire pond a partial liner will only leak or slip away the clay should be knitted into existing soil or it will not bond to the slopes usally an 8 inch knit if many rocks more clay in the mix if no mixing water entering from behind will lossen clay and it will settle to the bottom you might get away with that method if the pond was shallow and eased sides you want any leakage to take the clay with it to mix and seal
Always install clay to the top rim of the pond and and areas where runoff comes in strong take the clay mix up on shore
Good Luck Scott
