vincent p. norris wrote:
I have read that some grasses (perhaps not our typical lawn grasses)
send roots down many feet into the earth.

Can anyone confirm or refute that or refer me to a source of info
about it?

You want "Tall Fescue", not red fescue or other ordinary types. It
has worked well for me. Reference http://www.paulparent.com . Use
the "Search this site" box in the upper right to search for "Tall Fescue".

Lofts "Rebel II" is 100% Tall Fescue. I believe Scotts has some also.
Read the labels carefully.