sub-slab depressurization system 3

https://victor-wiki.win/index.php/The_Sump_Pit_Radon_Seal:_A_Critical_Component_for_Radon_Mitigation_in_York_County

A sub-slab depressurization system is installed beneath concrete foundations to prevent soil gases like radon from entering homes. It consists of a network of pipes embedded in gravel below the slab, connected to a fan that creates negative pressure. This continuous suction draws gases away from the building and vents them safely outdoors, protecting indoor air quality without being noticeable to occupants.