On every job a vacuum/communication test is performed on the concrete slab. This procedure will determine system selection, choice of fan, exact layout of the system's piping, and the number of penetrations through the slab.
Active Soil Depressurization (ASD) is the system of choice for most radon mitigation. The theory behind ASD is to depressurize the area beneath the concrete slab. The system consists of a path and a mechanical device to transport radon-laden sub-slab soil gas to above the structure's roofline where the radon will dissipate naturally. The ASD system may provide an added benefit of a dryer basement.
Heat Recovery Ventilator (HRV) is the alternate system to the ASD. The HRV may be used in conjunction with the ASD or as a stand-alone unit if levels dictate. The HRV is a mechanical device which filters the air in the basement. The HRV introduces a continuous supply of fresh air into the basement while also exhausting radon-laden stale air to the exterior. This radon removal process is a method of filtration and dilution.
A site visit is not mandatory, although, strongly suggested to inform the client of system requirements and possible locations.
The contractor needs to know:
How old is the structure?
What is the radon level?
Are there any openings, sump pumps in the concrete slab?
Are there additions, crawl areas, or any exposed earth?
Are there any basement de-watering issues?
Is there radiant heat in the concrete slab?
Sump Pump Installation
A high water table (ground water) may disrupt the air flow of the mitigation system. Blocking the airflow may
cause the fan to burn out. A sump pump installation should alleviate this problem.