How close is your well to the proposed sewer line? In our county, wells have to be 100 feet from sewer/septic areas but exceptions can be granted if it's impossible to achieve that distance. In your case, the county health department might be willing to grant an exception if the distance isn't so close that contamination is likely.
As an alternative, I would look into whether you could have the irrigation well turned into your drinking water. I'd be loath to lose cheap drinking water and, quite frankly, well water can be cleaner than public water. Here in Southeast NC we get our public water from the Cape fear river and Chemours has been dumping GenX in the water for decades. We basically have the highest PFAS contamination in the country. I'd take well water over public water all day long.
The biggest thing with irrigation wells is that they typically don't drill as deep because it's cheaper. Water from shallower aquifers tends to not be as good as deeper aquifers but you could take samples from each of your wells to know for sure. You should also be able to grab the well permit number off the placard around your well cap and the county health department can tell you some info about that well such as drill depth, when it was drilled, etc.
As far as compensation goes, I have less advice there. Here when they run water through they force you to hook up in order to subsidize the system, which I think is bullshit. At a minimum, if they are forcing you to abandon your well I would seek a waiver of the assessment fee and free hook up to the water system.
You mention them wanting to get to the well house. Do they want to cap the well? I don't understand why they can't just abandon it by removing the well pump and plumbing from it. Maybe there's some environmental regulation that forces them to cap a well if it's within a a certain distance of a sewer main?
