For an installation of this size, the customer is not going to settle for anything less than near perfection. That is the caliber of pond contractor that you will be seeking.
Some basic guidelines are
Years in business (experience)....no less than 10 years installing and maintaining aquatic habitats.
Knowledge.....very familiar with the biological requirements of a pond this size.
Insured (or can get it).
There are probably a great many "Pond Installers" in the Greater Atlanta Metro area, but what you are looking for is a Specialist.
Feel free to PM me if you like.
"Everybody is ignorant, only on different subjects." - Will Rogers