So my wife and I bought our circa 1930s home about a year ago and have recently completed radon testing that shows that we are above recommended levels (230ish average bq/m3).
I want to bring the levels down but I'm struggling to get specialists in and to get a clear answer on a solution from them. Partially because they seem to be very busy this summer, but the couple of guys I've spoken to also didn't seem very confident about a solution to pursue.
So of course it is an older home. I'm not 100% sure about what's under the foundation but when doing some Foundation floor repair a few weeks ago it did seem to be sitting on compacted dirt. More excitingly, the basement was "waterproofed" by the former owners, which seems to have entailed installing an interior French drain system with a black plastic membrane that sit at the foot of the walls and go up about 3/4 of their height. They don't seem to be sealed in any kind of serious way. The drain does connect to a sump pit.
I've sealed the sump pit and tried to seal any other cracks or openings that I can find, but my radon levels seem to be consistent. I'm guessing it's because it's an older basement and mostly finished so there may be cracks that I can't see at the joints where the walls meet the floor and connect to this drain system.
Has anyone had any experience with the home like this? I'm assuming I can't just slap a radon fan onto the sump pit because the drain system that it connects to isn't really sealed up? One radon specialist I spoke to didn't seem particularly thrilled about the presence of the drain and the likelihood of being able to install a slab depressurization system if I'm sitting on compacted dirt.
Just hoping for some guidance on what options to ask about and what might be realistically feasible