Drill a 6” hole through the concrete foundation and dig out about 15-20 gallons worth of material. Install a 3-4” PVC pipe into the hole (the end of the pipe should be a few inches below the bottom of the foundation) and seal the hole up with hydraulic cement. Continue the PVC pipe up out out of the house. There are lots of rules around distance of the outlet from windows and doors and how high above roof line. Inline install a radon fan. How big a fan you need depends on many factors like soil type, home dimensions, etc. The fan runs 24/7 creating a vacuum under the house.