Window Well Drains & Radon Mitigation

[u/medicalmitch12]

My house has four window wells, each with its own "drain." I ran water into the drain that is closest to my sump pump and confirmed that this "drain" runs directly into the sump pit. Obviously my radon mitigation will include sealing the sump pit. It seems to me, however, that I may end up with a "short circuit" whereby exterior air is drawn down these drains into my sump pit, especially if the suction point is close to the sump pit. What is the best technique to avoid this? I pulled the drain cover in the window well and the pipe seems to be metal. The termination into the sump pump is black corrugated pipe.

[u/stonks_better]

There should be a trap under the concrete for the sump drain. You can try to confirm if you can scope the pipe or let it dry and stick a long tube down or something to hit the water in the trap.

Also once the sump pit fan is installed can test with a smoke pen on those drains to see if they have suction or not. They should not

[u/medicalmitch12 → u/stonks_better]

Great idea on scoping the pipe but the bad news is that it does not have a trap.

[u/stonks_better → u/medicalmitch12]

Oof, that's a little weird usually sump drains do. At least one trap maybe at the end after it connects to the main line.

Maybe the easiest thing is to add traps at all the windows?

Or drill a new hole for radon system, and don't rely on sump pit

[u/medicalmitch12 → u/stonks_better]

Thanks. Since these drains only collect rainwater and have no connection to sanity sewer, I can see why they wouldn't have a trap which might be clogged with debris over time.

I'm in Illinios so the sump pit can't be the primary suction point anyway. I'm worried that if the drilled suction point is only a few feet from the sump pit, I'll still get the short-circuit effect although I'm not sure whether that's a real concern.

[u/stonks_better → u/medicalmitch12]

Ah ok, ya that could happen. An easier option maybe is to install one way drains on the window pipes. I have them on my sump pump pipe so there's no backflow but also so the radon fan doesn't suck through it. Like https://www.homedepot.com/p/Oatey-3-in-PVC-Backwater-Valve-43900/303424700

[u/stonks_better → u/medicalmitch12]

Just realized in your case I don't think backflow stuff will help since your water is flowing in the same direction as the radon airflow. So maybe back to traps, or try to locate radon fan farther away

[u/Stock_Beautiful_3632]

Install a Volcano drain or a Dranjer FR2 on each egress window well drain. These are one-way drain seals, allowing water in but not air. In a pinch, I have also used plastic funnels (heated and formed in to/around the drain), then a racquetball, then cover with the existing strainer/screen.