If your soil won't hold water, you will need to bring in some clay to line the bottom (some suggest a minimum of 2' thick).

I doubt the road crew has that factored in, but you never know.

Then, consider what your sources of water are going to be. Do you have enough run off to fill the pond, or are you using well water?

Excerpt from Robert Crais' "The Monkey's Raincoat:"
"She took another microscopic bite of her sandwich, then pushed it away. Maybe she absorbed nutrients from her surroundings."