The following LSPA practice tip was introduced at the June 2026 Membership Meeting, which was held via Zoom on Wednesday, June 10, 2026, from 3:45-5:00 PM.

Practice Tip  
In MassDEP’s Vapor Intrusion Guidance: Site Assessment, Mitigation, and Closure (Policy #WSC-16-435, Section 3.7), MassDEP recommends that for sampling to demonstrate that an active or passive mitigation system is no longer required to mitigate the vapor intrusion pathway, the vent pipe should be capped or the valve to the vent piping closed during the sampling event. For an active system, the vent or valve needs to be closed prior to sampling as well. Based on discussions with MassDEP, it is recommended that the vent/valve for an active system be closed at least seven days prior to sampling, consistent with the recommendation for deactivation of the system that is in the guidance.

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