Usually just messing with them, disturbing the nest will convince them to move elsewhere. It may take that size of community a while to pack its bags and move on.

Do I have to put on a haz-mat suit first?
I'm allergic to insect stings/bites.

Use a long handled shovel and dig things up a bit and then soak with a garden hose - all from a safe distance. You'll have to torture them every day but they will eventually move the hive somewhere else (probably still in your yard but not so close to the house).

Dear dottie_in_charlotte z7-8 NC,

Please see my reply to tlmckay 7b.

jay_in_central z8a SC

P. S. Here's a bit of trivia for you: _Central_ is named _Central_ because it is halfway between Charlotte and Atlanta on the railroad.

Well, thanks but I think this nest is as well located as possible to be out of my way and obvious enough to be avoidable.
I think I might put a dark green painted wire fencing (open and decorative and not very noticeable)around it to keep the grandkids from walking on the nest. I have visions of it collapsing under the weight of a human.
The two smaller satellite nests are of no concern and the house isn't overrun with ants (never seen any indoors).

Word of caution, make sure you keep up your annual termite inspection on your home. They will catch damage and problems with Carpenter ants as well as termites under your house. Having had an Ex FIL who owned an exterminating company, I know they can do some damage to a house. Good luck on convincing them to move along to another area.

Dottie,
If I were you, I would call a local exterminator to come take a look at what you seem to not take seriously.
Carpenter ants eat termites for breakfast.
They ate the inside out of an apple tree I once had in one summer, and it fell on my neighbors house. No joke.
Just get their opinion on it because the nest is a good size one. They will understand about your well, they know how to handle that.
It never hurts to ask.
It hurts to replace your home wood, or when a tree nearby falls on it. Ouch!

I found a very large one near my home and I agree with butterfly4u I am calling an exterminator. Carpenter ants scare me....they can do a lot of damage.

Carpenter ants will not harm a live, healthy tree. They indicate there is something wrong with the tree- there was rot or something they were working on. My dad grew up as a lumber jack and they knew to look for trees that carpenter ants had/were working on; that meant they had punky spots and weren't good for logging.

We have big nests of them in our back yard and have never had issues with them. They don't come in the house (though they did in the house i grew up in, in PA). The ones in our back yard make nests probably close to 4' wide, but they don't seem particularly aggressive, though i wouldn't stand in the middle of one, either. We just work around them and they move around some through the years. Incidentally, though we have fire ants up front where i've not seen the carpenters much or at all, we still don't have the fire ants in back where all the carpenters are. I'll take the carpenters any day of the week.