RMS-LB 2018 with 12/20 Revisions

Note—12/20 revision — (This Section is now identical for AARST: SGM-SF, RMS-MF and RMS-LB) ANSI/AARST RMS-LB 2018 (with 1220 revisions) Radon Mitigation Standards for Schools and Large Buildings 15 6.0 ACTIVE SOIL DEPRESSURIZATION (ASD) 6.1 ASD Suction Points 6.1.1 Suction pits A cleared void space shall exist or be created below all suction points through slab floors and to the side of all suction points through walls, unless excavation is not practicable. This cleared void space shall be not less than 0.25 ft 3 (7 dm 3 ) which equates to 2.0 US gallons (8 L) of excavated sub-slab soil/aggregate. Exception: Where multiple suction points are employed, secondary suction pits designed for condensate drainage or airflow balance are permitted to have a smaller cleared void space. Informative advisory —Where sub-slab material exhibits poor permeability, larger pits are recommended, such as 1 ft 3 (28 dm 3 ) or larger. This void equates to 7.5 US gallons (28 L) or more of sub-slab aggregate. Note—Pit size needs are based on permeability of the sub-slab material. If the combined surface area of exposed pore openings between granules of soil, sand or gravel is less than the cross-sectional open surface area of the suction pipe, as shown in Table 6.3.4 , a larger pit will likely enhance PFE . Seal the Suction Point Gaps in concrete surrounding suction pipes shall be sealed in a permanent, airtight manner. When using caulk, the gap opening shall be cleaned and sealed with caulk complying with ASTM standard C920 class 25 or greater. To support caulk while it cures, gap openings greater than 1/2 inch (13 mm) in width shall be pre-filled as needed with backer rod or comparable material prior to applying caulk. Drain-tile Suction Where the suction pit or suction piping directly accesses soil air from a drain-tile, the configuration shall not result in compromising the capacity of the water drainage system. 6.1.2 Sumps Informative advisory —Sumps that connect to soil air should not be used as the primary suction point unless other options are inadequate for achieving PFE . Concerns include compromised accessibility to pumps, increased noise, and some localities disallow use of a sump as the primary suction point . Seal the Suction Point (sumps) Where sumps are used as a suction point , sump lids shall be sealed in accordance with Section 7.5 in an airtight manner. Accessibility to Sumps Provisions of Section 7.5 for sealing sumps shall be observed to include that a physical access port or equivalent is required. Flexible coupling disconnects for suction piping, in accordance with Section 6.2.6 , shall be provided to ease sump lid removal. Informative advisories —(1) The suction pipe should not extend lower than 1 inch below the sump lid. (2) Visual access to conditions in the pit is recommended. (3) Flexible coupling disconnects should be located such as to facilitate easy removal of the cover. Suction Pits Pipe to Fan Pit example Sumps Pipe to Fan Sump example Drain-tiles Pipe to Fan Drain-tile example