Planting near a well--how close? Nankings and maypop.

I am putting in a fence around our yard and wanted to plant a nanking cherry hedge along the outside of it. 7 feet out from the fence line there is a well. If my hedge is four feet wide, I would want a two foot space from the fence, so the bushes would be planted about 5 feet from the well, is that too close for comfort? My concern is exploring roots damaging the well in any way. I was thinking I will have to I plant the cherries on the inside of the fence although that is not my ideal location. I want to plant a maypop somewhere on the fence too, but am wary of planting it anywhere near the well because of it's aggressive spreading. Should I be concerned? Zone 6a

Is it a modern drilled well with a steel casing? If so, I simply don't see how either plant could pose a threat to it.

Now if you're talking hand-dug wells with field stone facing in the shaft, or something your Uncle Jimmy did up with a sand point and a big hammer and a piece of used PVC sewer pipe, then it would be time to worry about roots.

Dan, thanks for writing, it's much appreciated. I believe it is a modern well but I will double-check.