I pushed our RE agent hard regarding radon in the area before we bought. He looked at me like I had two heads. That agency has sold thousands of houses in the area and had no idea about any radon readings (positive or negative). Fack. Not exactly something you can check before conditions are cleared. Just buy and hope for the best.
As I understand it, it is substantially similar to ground water so an area may generally have issues (or not) but within the area, individual houses may not experience the same issues as their neighbours. All of my neighbours apparently have sump pits, many of them hear their pumps cycle often, I don't have a pit (or ground water issues). From street level, the grading/slopes etc all look similar.
That could change.
I was called to investigate why a residential snow melting system wasn't working (Near Downsview Airport)
The history was that an existing system stopped working and the owner called in a guy to replace it. He did so without testing the old system consisting of IIRC four cables. It is extremely rare to have four cables fail at once.
The replacement system also failed t melt snow even though it was the right output. Over a period of five years they tried everything to get it to work, boost transformers and cable modifications on site and improvement was marginal. Then a couple of years ago it started working.
The only thing I could come up with was that by looking at Google maps street view, about the time the cables stopped working the modest house next door was torn down and a bigger one built. Did something affect the ground water and quench the cables or????
There was a freezer plant in Hamilton that had a similar problem with the floor heaving in the spring. It was slab on grade, more like slab on swamp. In the spring walking across the parking lot felt like walking on a mattress.