SGM-SF_2017with 12/20 Revisions

Non-ASD Methods 49 ANSI/AARST SGM-SF 2017 (with 1220 revisions) Soil Gas Mitigation Standards for Existing Homes c) SVE — Soil Vapor Extraction (including recapture methods and disposal of contaminants of concern. For information, see EPA's “Soil Vapor Extraction (SVE) Technology” EPA-600-R-18-053. 12.12 Air Cleaning Informative advisory — Radon gas itself cannot be cleaned from indoor air. Radon's decay products that do represent the substantial risk from radon exposure are partially cleaned from the air as solid particles. A portion of these elements have attached are cleaned from the air with filtration or other technologies or activities. However, challenges of using air cleaning as a mitigation method that are beyond current technology include: a) the degree to which radon decay products and their associated risks can be verified to have been truly removed from the air; b) systemdesigns to ensure consistency of air cleaning along withmechanisms to adequately warn occupants when filters or systems degrade in performance; and, c) system design specifications and standards that can ensure all radon decay products, including those not attached to solid particles and those that constantly form downstream from any air handler system, are removed from the air throughout multiple effected airspaces. Currently published and peer reviewed science does not support that the amount of risk reduction sought can be quantified or verified for consistency with current technologies. Consistent with EPA technical guidance publications 11 , air cleaning as a means of reducing the risk from radon is not recommended as a mitigation method. 12.13 Passive Methods and Systems Informative Advisory—Passive Methods Where any passive method is employed as a standalone mitigation method, vigilance is warranted for verifying effectiveness with indoor measurements to include testing for seasonal differences and other effects across time. Note—Under specific circumstances, passive technologies for reducing soil gas entry can be effective to the degree to which: a) the connection between soil air and living spaces can be broken; and b) natural forces that drive soil gas into a building can be minimalized or neutralized However: Achieving a complete and comprehensive break in the connection between soil air and indoor air is not truly possible or sustainable; and efforts to counter natural forces that drive soil gas entry using passive means are often unreliable or unsustainable. 12.13.1 Sealing openings to soil Sealing is not to be regarded as a permanent, stand-alone mitigation method. Informative advisory —Historically, technology portrayed by EPA for soil gas mitigation has included a wide scope of options accompanied by an evaluation of cost and effectiveness. Between 1986 and 1992, this resulted in a phased-in strategy of trying sealing alone as a first step. Considerations included cost and studies that indicating as much as a 50% reduction could sometimes be achieved by sealing alone. By 1992, field experience of unreliable effectiveness and sustainability warranted the following position statement: “EPA does not recommend the use of sealing alone to reduce radon because, by itself, sealing has not been shown to lower radon levels significantly or consistently.” 12 12.13.2 RRNC—Home construction design Note—Techniques employed during new construction of buildings are beyond the scope of this document. See ANSI/AARST CCAH, “Reducing Radon in New Construction of One & Two Family Dwellings and Townhouses.” The practices therein, that are normally not practical after construction, are based on both: a) breaking the connection between soil air and indoor air; and b) minimizing natural forces that drive soil gas into a building. 11 EPA/625/8-87/019 January 1988 "Radon Reduction Techniques for Detached Houses (Second Edition)" (Section seven, third paragraph) and EPA/626/6-88/024 August 1988 "Application of Radon Reduction Methods" (Section 10.6, third paragraph). 12 The EPA “Consumer's Guide to Radon Reduction” 402-K92-003, August 1992 and 402/K-10/005, December 2016