How crawl space radon systems work
When there is no concrete slab to drill through, the installer covers the crawl space floor with a heavy plastic membrane, seals it to the foundation walls and piers, and connects a vent pipe and fan under the membrane. The fan pulls soil gas from beneath the plastic and vents it above the roof, the same principle as a sub-slab system.
Homes with more than one foundation type
A basement under the original house with a crawl space under an addition is common in Omaha. Each area may need its own suction point, tied into one fan where possible. Mention every foundation type in your request so the estimate covers the whole house.
Related: sub-slab radon mitigation.