So far, all indications are, P2 is the
only abnormal Radon source..
It was down to 4pCi/L at the P2 pump (with cover installed) and dropped to 3 pCi/L at P3 (open top).
So, this morning the sensor unit is over on the old P1 sump again..
Water level in P3 is now 2" (and dropping). Less than 1" in P2. P1 & P4 are dry.
I used a shop-vac to test the coroplas seal on P2 yesterday. It's not that good.
Air is flowing into the sump. It's flowing under the floor tiles.
The tiles have water drainage channels on the bottom side.
Waterproof Basement Flooring System - Place N' Go: Fine Flooring for Basements
So of course a good amount of air can get under it at the edge.
I'm going to have to put on the mask and silicon seal under the tile all around the sump hole..
Edit: 9AM 12/12/11
Still at 3 pCi/L @ P1
This is another good indication that my Radon problem is isolated to P2.
Which seems a little odd, but should make the job much easier.