Our slab radon level was extremely high at 27 ppm with the house closed up and the test pad over the radon exhaust pipe that was not yet hooked up. Safe level is 4 ppm. We knew we had to mitigate for radon and the test confirmed it. But what are the parameters of radon mitigation? These are the resources I used to plan our system.
2010 Sub-Slab Depressurization Report Part 1
2010 Sub-Slab Depressurization Report Part 2
Originally Downloaded from but no longer linked:

Overview Of Two Large-Scale Residential Sub-Slab Depressurization Installation Programs

Radon Resistant Buildings

Passive Radon Control

Radon info

Subslab depressurization systems

US Radon zone map