Good call!. Pompey the Cary flow tests won't affect you out there; but most fire departments or the water company flow test hydrants every other year if not annually so keep an eye out for when they start going around (Especially as the weather gets nicer)
Where did you hear about extra ammonia? I read exactly the opposite in the Raleigh Utilities insert in my water/sewer bill, which says the two Raleigh water treatment plants will STOP adding ammonia and just use chlorine from Feb 26 to Apr 9, while flushing pipes. A normal dose of Prime or similar chlorine/chloramine remover will still work fine; you dont need to double it.
I think Durham follows the same schedule as Raleigh. Not sure about Cary-Apex water system's flushing schedule.
The guy from the ToC water told me about the Ammonia. Maybe I misheard him or he mixed up his facts. Not concerned either way since RODI seems to catch it. I was just concerned about flush sediment clogging up my new filter.