Mine was also "packed with at least a foot of good clay all around", and improperly compacted by a bulldozer. With only 0.2 inches of rain since Feb 28, it has dropped almost 20 inches in 23 days by leaking at the dam-bowl junction. Clay liners by themselves are not at all effective if not compacted properly, and no amount of settling by themselves over a span of several years will help.
