A Comparison of Approaches to Methane Mitigation in New Buildings
Significant developments have been made over the past decade or more with the mitigation of the vapor intrusion pathway for volatile compounds. Many of these developments can applied to sites where methane is the driver for mitigation. However, there are unique and important differences for mitigation of methane VI potential. Recent urban infill and Brownfields redevelopment trends have pushed methane-impacted sites to the forefront and prompted regulatory responses. Currently there are a few states that have specific guidance for addressing methane in soil gas – however, there is not nationwide consensus on how methane in soil gas should be dealt with. Many local agencies have methane regulations that apply within their jurisdictions which can make methane mitigation a more granular problem than chemical vapor intrusion.
Methane can be present in the subsurface from a variety of sources, and often the source type will play a significant role in the approach to mitigation of the VI pathway. This presentation will describe common site models where methane is typically found, and provide a summary of approaches to methane mitigation. An overview of current state and local guidance for methane mitigation will be provided. Case studies will be shared to describe scenarios where common approaches to mitigation could be applied – for example, SSD and SSV, as well as passive and active operation.
Three case studies will be shared for the purpose of describing some nuances related to SSD and SSV for methane, as well as to describe differences in the approach to mitigation when using aerated floors and traditional gravel and membrane systems. Finally, a summary of approaches to long term stewardship of methane mitigation will be shared.