It depends 100% on the soil type you have. You’re down southeast, past the piedmont, right? If so, you’re in a different soil type than I’m used to messing with here around Charlotte—and even then I’m no expert.
I had to do a non-conventional system on a project that had “bad soils.” It consisted of a grinder and an aeration system to help chop up everything and encourage it to start digesting. Then a drip line system that is super finicky. The lines are essentially 0-slope flat, laid out by a surveyor on the same contours for each line. The solid has to be hand-manipulated (no equipment allowed as it will compact the soil and make it worse).
There are different flavors for different scenarios. The setup I described was for a public park. A house would be less elaborate.
I’ve heard ballpark figures of $20-$30k for a residential drip and/or other non-conventional system.
In Meck County, they make you preserve a repair zone for future failure of the system, regardless of the soils. Yet another area you cant do anything on—no sheds, equipment, driveways, etc.
Get with a septic designer and/or soil scientist that knows your area—more importantly, knows your County’s inspectors. They’ll have a good idea of what will fly and what won’t. Design costs could be about $3k-$5k.