An Active Soil Depressurization system can be one of the following or any combination of:
Active Sub-Slab Depressurization
“Sub-Slab Depressurization (Active)” or “SSD (Active)” means a radon control technique designed to achieve lower sub-slab pressure relative to indoor air pressure by use of a fan-powered vent drawing air from beneath the concrete slab.
“Sub-Membrane Depressurization” or “SMD” means a radon control technique designed to achieve lower air pressure in the space under a soil gas retarder membrane laid on the crawlspace floor and sealed, relative to air pressure in the crawlspace, by use of a vent or fan-powered vent drawing air from beneath the membrane.
Drain Tile Depressurization
“Drain Tile Depressurization” or “DTD” means a type of active soil depressurization system where the suction point piping attaches to a drain tile or is located in the gas-permeable material near the drain tile. The drain tile may be inside or outside the footings of the building.
Block Wall Depressurization
“Block Wall Depressurization” means an active system that depressurizes the void network within a block wall foundation by drawing air from inside the wall and venting it to the outside.