SGM-SF_2017with 12/20 Revisions

Additional Requirements—Chemical Vapor Intrusion 54 ANSI/AARST SGM-SF 2017 (with 1220 revisions) Soil Gas Mitigation Standards for Existing Homes mild variations dependent upon the season. PFE test data witnessed when outdoor temperatures are within 10 F of the average for coldest local temperatures will typically characterize worst-case PFE (See Annex B-3 and B- 4 for indoor air test recommendations). 13.4 Additional System Specifications 13.4.1 Durable ASD pipe configurations Informational advisory —Design and installation of ASD should result in pipe configurations that are highly resistant to water escaping the pipe at any location other than as designed (e.g., to the ground beneath the slab or soil-gas retarder membrane). Water forms consistently within ASD piping during colder seasons as vapor condensates. This water can sometimes contain concentrated chemicals and warrant special evaluation and cleanup procedures if escaped from piping. Best practices for enhanced durability a) Ensure that primers and solvents are applied in accordance to pipe manufacturer instructions; b) Avoid any off axis and partial insertions of pipe into the receiving elbow, coupling or other joint and minimize the number of joint connections; c) Ensure supports and routing design protects pipe joints frommovement as a result of blunt force impact or even incidental movement of a horizontal pipe that can twist joint connections and eventually cause joints to leak. 13.4.2 Non-habitable air spaces Informational advisory — Depressurization of non-habitable airspaces as described in Section 6.1.4 should include design features to provide sufficient outside air to inhibit soil gas vapors or outdoor humidity from condensing on building materials. 13.4.3 ASD pipe material 13.4.3.1 Downspout materials identified as an alternative to plastic pipe in Section 6.2.5, Exception 2, are not permitted for use as ASD duct pipe materials when ASD goals include mitigation of chemical vapor intrusion. Note—Such materials enhance the likelihood of condensed water escaping from the duct material that can sometimes contain concentrated chemicals. 13.4.3.2 For pipe materials identified in Section 6.2.5, Exception 1 , an an evaluation shall be made prior to installation for appropriateness as it relates to corrosive effects that chemicals may have on the iron, steel, copper or other pipe materials. 13.4.4 Exhaust configuration Informational advisory —The exhaust configuration, including straight-line discharge separation specified in Section 6.4 , should be reviewed by the overseeing team for acceptability and for any need to be additionally modified due to consideration of both system airflow and stack gas concentration measured or modeled. 13.4.5 Additional ASD fan requirements An explosion-proof fan or as appropriately specified by codes 13 is required when evaluations of the chemical(s) or substances of concern indicate that gasses passing through the fan could result in a fire, explosion and serious personal injury to workers and building occupants. Note—Most inline fans commonly used for radon reduction are not rated as explosion proof. See the Companion Guidance for more information. Informative advisory —The electrical power should be disconnected from the fan unit in any situation where the gas concentration is expected or found to exceed 10% of the Lower Explosion Limits (LEL) as published for certain common chemicals. 13.4.6 Sealant materials The contractor shall advise the client if any sealant products used are known to have long curing periods or contain constituent chemicals identified for mitigation . Note—Curing compounds, including constituent chemicals identified for mitigation that have not stabilized to a benign or minimal state, can corrupt post- mitigation tests. 13 See the latest version of the National Electric Code published by NFPA: www.nfpa.org