How far should access entry be located from the ASD fan?

The correct answer is based on guidelines that suggest a 30-foot distance for access entry from the Active Soil Depressurization (ASD) fan. This distance is important for a few reasons.

First, maintaining a safe distance helps ensure that any potential soil gas, such as radon, does not re-enter the building through the access point, especially during maintenance or inspections. The 30-foot distance acts as a buffer to limit the amount of radon that could travel back toward the building from the ASD system itself.

Additionally, this distance takes into account the need for efficient operation of the fan. Being too close might introduce complications regarding airflow dynamics and might also contaminate the fresh air being drawn into the system. Thus, keeping an appropriate distance minimizes the risk of radon accumulation near the entry points while ensuring the efficacy of radon mitigation strategies.