I advise customers to claim those things that are defensible. If you already need a well (new construction) is it reasonable to say the geo system caused the requirement? Incidently you could ask the same question of ducts.
I looked at a job today where existing system was a steam boiler. I can defend the "duct requirement" ducts are cheaper than in floor radiant loops. One or the other is required for geo.
If you already have a well and the geo requires more GPM, I think you can defend the point that it is required by the system. We are exploring open loop that would discharge into storm drain (house is on city water)....I think we could defend the cost of the well which would be thousands cheaper than 5 vertical closed loops.
Ask your contractor to be careful about contract verbage........""including necessary well delivery improvements".....
At the end of the day....
Ask your tax preparer.
Good luck,
Joe