How Radon Mitigation Works
By Steve Vacha
Radon is a gas that is released from uranium that is found in shale rock deep in our soil. Radon gas has a radio active charge to it. In the early days of recording levels of radon gas, one method was to direct air to a thin plastic instrument. The radon gas with its radioactive charge would make a small indentation on the plastic, a small radioactive blast so to speak. The marks on the plastic were counted to determine the level of radon gases in the air. That is the concern – if the radon is marking the plastic instrument,what is it doing to our lungs?
To reduce radon in most of our homes with basements or built on slab we use an active sub slab suction method. We are capturing the air/gas that is released under our concrete floors and directing it outdoors, where it is of no concern. When a sump pit is present in the home, with drain tiles draining into the sump pit, this is usually the access point for the radon mitigation system. In most newer sump pits, a black perforated pipe is run along the perimeter of the basement walls and it drains to the sump pit. To mitigate the radon under the foundation of the house, the mitigation contractor will usually run a 6” PVC pipe into the pit and seal the lid with a plexi-glass lid sealed with caulk. A suction pump is then installed in the pipe, to creating the suction to pull the air out from underneath the slab. Most homes will need one access point, larger homes might need two access points .If a sump pit is not present in a home, then a hole is cut into the concrete floor, a small pit is dug and the PVC pipe is placed in this small pit and sealed. There is a hallow spot between the concrete slab and the subsoil. This is caused by the soil drying out after the concrete has been in place for a number of months. This¾ “cavity” under the slab is enough space to create this sub slab depressurization.
Testing after the system has been installed is important to verify the system is working properly. There is little maintenance needed for the system other than verifying the fan is working by checking the fluid gauge.With a properly installed mitigation system, even houses with high radon readings can be made to have low and safe levels of radon gas.