SGM-SF_2017with 12/20 Revisions

Additional Requirements—Chemical Vapor Intrusion 52 ANSI/AARST SGM-SF 2017 (with 1220 revisions) Soil Gas Mitigation Standards for Existing Homes 13.2.2.1 Additional Testing or Diagnostics The contractor shall advise the client in writing if additional testing or diagnostics are recommended when existing disclosures are insufficient to characterize the dynamics of soil gas entry into the building as it relates to diminished capacity for either: a) design of appropriate mitigation system(s); and/or b) protection for all workers and occupants of the building during mitigation diagnostics and system instillation. The contractor shall advise the client that additional testing or diagnostics may be warranted under the following conditions: a) Tested locations were of insufficient quantity; b) Time periods do not reflect average conditions for building occupancy; c) If test data beyond 1-year-old cannot be compared or be considered to reflect current conditions; or d) Testing practices do not comply with national protocols, state protocols or approved alternate methods deemed otherwise adequate by the contractor due to lack of appropriate closed-building conditions, test locations, test durations or approved test devices. Exceptions: The contractor is permitted to proceed with mitigation designs and installations when extenuating circumstances warrant immediate action. Note—Examples of situations that could warrant action, even though existing test surveys are insufficient, include but are not limited to: a) protection of occupants in areas that clearly indicate elevated radon or other pollutant concentrations; b) protection of occupants preemptively when perceived concerns or evidence suggests a potential concern exists; and c) time constraints for building use schedules and other client concerns. 13.3 Building Investigations 13.3.1 Additional visual inspections In addition to all requirements of Section 5.4 (visual inspections) , observations of failed or inadequate groundwater control systems shall be reported to include: standing water in a basement or crawl space ; evidence of groundwater intrusion; and failed pumps or sump systems inappropriately discharging contaminants. The contractor shall document and provide immediate or timely notice to the client regarding any safety hazards observed that were not identified in documentation received from the client . 13.3.2 Diagnostics required When the purpose of mitigation includes chemical vapor intrusion, diagnostic procedures are required prior to or no later than the onset of determining the final system design. Informative advisory— To what extent are diagnostics warranted? The cost of enhanced diagnostics can significantly reduce more excessive long-term stewardship costs while maximizing reliability of citizen protection. Rewards of careful diagnostics include savings for unexpected test expenses incurred, along with costs for correcting misguided designs or poorly performing systems. 13.3.3 Additional ASD diagnostics Pressure field extension (PFE) analysis in accordance with Section 5.5.1 is required. 13.3.3.1 PFE Testing PFE test locations shall be created, evaluated and documented in the OM&M plan. Minimum requirements include: a) The air pressure differences shall be evaluated and documented for natural state (pre- mitigation ) and the effect of fan-induced vacuum as indicated for each permanent and temporary diagnostic hole or PFE test location; b) At a minimum, PFE pressure differences are to be evaluated under closed-building and normal operating conditions.