I need some help trying one last thing about keeping the animals out
from under my deck. The best choice is to have it ripped up and
replaced with a concrete patio. However, I think that will cost me at
least $10K. I'm going to get an estimate but want to try one more
thing before I do that. Right now I have at least two ground
squirrels and a raccoon living there who come out periodically in the
day/evenings.

Whenever you think they are in there, get a weapon of your choice and climb
in after them. They will tire of this challenge very quickly.