The MPCA has developed procedures for vapor intrusion mitigation and public communication work used by the agencies and our contractors. The procedures and documents were developed working closely with the Minnesota Department of Health, environmental consultants under contract to MPCA, and expert practitioners in radon mitigation.
Investigation and mitigation decision best management practices
- Appendix B — Video: MPCA Sub-slab sampling methodology: demonstrates steps for collecting a representative sub-slab vapor sample from beneath a building's concrete floor.
Building mitigation best management practices
- Attachment A —
- Attachment B —
- Attachment C —
- Attachment D —
Parking facilities and vapor mitigation
Soil vapor contaminated with non-petroleum and petroleum related VOCs may enter parking facilities and then adjacent occupied spaces. The MPCA has developed a summary of readily available literature, codes, parking facility products, experiences with parking facility forensic investigations, and discussions with design engineers.
Intrusion screening values
Chemical-specific, risk-based inhalation screening criteria for volatile compounds, used to evaluate indoor air quality.
Public communication best practices
- Build partnerships. The community, residents, property owners, and local and state governments are all important partners on vapor intrusion projects.
- Make a space for partners to participate. Respect and honor everyone involved.
- Show your commitment to the community and the project.
- Follow through and be available.
- Connect with partners early and stay connected throughout the project.
- Adapt your communication style to meet the needs of the person or audience.
- Respect and honor feelings. All feelings are valid. Hear and acknowledge all concerns.
- Communicate clearly. Be clear about what you do know and what you don't know, and what the process is for figuring out what needs to be known.
- Use plain language.
- Be accurate. Know the facts and the science.
- Let people know how they can get their questions answered.
- Listen and adjust. Pay attention to feelings—yours and others. Listen to what is being said, and just as importantly, listen for what is NOT being said. Pay attention to what is being communicated to you in writing.
- Vapor Intrusion 101 (WiDNR) — Using a hand-drawn/animation technique, this video introduces the concept of vapor intrusion to people who may be unfamiliar with it by showing the root cause, how it spreads underground, and what can be done about it.
- The Responsible Neighbor: A Vapor Intrusion Story (WiDNR) — A video for consultants and responsible parties shows how good communication with neighbors benefits everyone involved with an environmental cleanup.
- Your health and vapor intrusion - residential (MDH)
- Your health and vapor intrusion - commercial (MDH)
Vapor intrusion guiding principles
The vapor intrusion guiding principles are the basis for the more detailed direction and guidance outlined in the vapor intrusion BMP’s.
- Underground chemical vapors can migrate from the source of contamination through the soil and building foundations into indoor air creating a health concern.
- The primary goal of vapor intrusion work is to identify and address potential human health risks.
- Effective public communication is an essential aspect of vapor intrusion work. This includes public awareness of health risks from vapor intrusion, vapor intrusion areas of concern, areas where mitigation has been installed and areas where more testing is needed.
- Building mitigation decisions are based on current and future possibilities of a health risk from vapor intrusion.
- Multiple factors contribute to variations in soil vapor contaminant levels.
- Seasonal sampling from multiple sampling points are needed to determine there is no vapor intrusion risk.
- The effectiveness of a mitigation system needs to be verified with confirmation testing.
- Expedited action is needed when the data indicates the potential for a short-term health risk.
- A plan is needed to assure continued operation of mitigation systems until data shows continued operation is no longer needed.
- Future property owners need to be notified of the presence and need for continued operation of mitigation systems or unresolved vapor intrusion risks.
- When there is a source creating vapor contamination, the best practice is to remediate the source if feasible.
- The obligation for addressing the possibility of vapor intrusion into a building and the source of the contamination are different for Superfund responsible parties compared to non-responsible voluntary parties and property owners.
- A clear and predictable process is important for timely facilitation of property transactions.