IEA_AARST_Radon_Reporter_JUNE_2024

22 | June 2024 RESEARCH The final system design included 21 suctions points and two roof mounted mitigation fans in order to mitigate the entire building footprint. The system design is shown below in Figure (4). FIGURE (4): NYC SUBURB BUILDING SYSTEM DESIGN Case 3: Building Influenced by Ground Preparation Prior to Construction This building, constructed in one phase, was built into a significant hillside. Due to the topography, the rear third of the building was located above grade that had been excavated and backfilled with gravel. The center third was on native soil and gravel. The front third of the building was on compacted native soil. PFE testing data produced three different ROIs based on the underlying soil. As shown in Figure (5), ROIs vary based on the underlying soil types and compaction rates. Conclusion Determining ROIs using proper PFE testing is required to design a SSDS system that ensures maximized efficiency and sub-slab vacuum coverage. As demonstrated in the above case studies, ROIs cannot be assumed or extrapolated based on limited data sets and must be calculated throughout the building. FIGURE (5): HILLSIDE BUILDING