When Clay goes bad, reinforcing ideas?
 

The pond (hole) has pretty much reached it's final shape now, except for
some debris I have to scoop out. The good thing about Clay is that I was
able to go straight down to the bottom with very little slope. This allowed
me to maximize my volume in very little space. The bad thing about Clay, is
that it's hard to repair if it gets damaged. The original pond was tight
against the sidewalk which meant that I could not change this edge of the
pond. Unfortunately the lip of the pond that the pavers sit on has collapsed
in in a few spots. (This is the sandy soil above the clay) This likely
happened when I removed the old liner, as there was some slumping in the odd
spot.

My idea to support the pavers (two rows) is to drive some rebar horizontally
under the sidewalk. But I have no clue how to encase the rebar. I thought of
pouring some cement, but I can see this cracking in short order. Perhaps
some kind of chicken wire only finer and made of plastic?