Which of the following is NOT a type of active soil depressurization (ASD)?

Active soil depressurization (ASD) is an important method used in radon mitigation to reduce radon levels in buildings by creating a negative pressure in the soil beneath the structure. This negative pressure helps to prevent radon gas from entering the building.

Subslab depressurization is a typical ASD system that involves the installation of a vent pipe or fan that creates a vacuum beneath a concrete slab in a building. This process helps to draw radon-laden air out from beneath the slab and safely expels it outside.

Submembrane depressurization functions similarly but is often used in crawl spaces where a plastic membrane is installed over the soil. This system creates a vacuum beneath the membrane to help hold back radon gas.

Sump system depressurization can also be an active method where a sump pump pit is used to mitigate radon levels. It involves modifying a sump pump that naturally collects groundwater to also vent radon-laden air to the exterior.

Wall-mounted depressurization, however, is not recognized as a standard type of active soil depressurization. ASD systems are primarily designed to target sub-slab or sub-membrane areas beneath the floors of buildings. Wall-mounted systems do not directly address the sub-slab pressures