I ask because I took out the old PVC liner today and I discovered that it no
loner touched the bottom of the pond when empty. It was in decent shape
after six years although perhaps a little brittle.

I was going to let the new liner settle (with water) about 24 hours before
cutting the hole for the bottom drain, but if the old liner is still
settling after six years!

The other bad news is that the weight of the water has turned the clay into
one large brick bowl, even the Mattock has a hard time breaking it up. I was
hoping that all the moisture around the pond would make the clay soft, but
that is not the case.