D04 · Sump-hole suction radon system

ALT TEXT
Labeled basement diagram showing a sealed sump connected to an active radon vent, fan, pressure indicator, and outdoor discharge.

LONG DESCRIPTION
A basement cross-section shows a sealed, serviceable sump interface connected to a vent riser and fan. Soil-gas arrows move toward the sump collection zone and vent airflow moves upward to outdoor discharge. The schematic does not prescribe a sump cover, drainage design, pump service arrangement, or water-control details.

Source basis: U.S. EPA Consumer’s Guide to Radon Reduction (2025), sump-hole suction description and typical-reduction table.
