Industry Update – Wisconsin Releases Comprehensive Vapor Intrusion (VI) Guidance

The Wisconsin Department of Natural Resources (DNR) has released its long-awaited Vapor Intrusion Guidance (RR-800), providing updated technical recommendations for assessing and managing vapor intrusion risks across the state. The new guidance, issued through the DNR’s Remediation & Redevelopment Program, is now available for download here: https://widnr.widen.net/s/xnmrpgkqqr

A key highlight of the comprehensive guidance is WDNR’s clear preference for passive sampling methods over traditional, short duration evacuated canister sampling for VI investigations. By emphasizing longer-duration, time-integrated passive samplers, WDNR recognizes that passive sampling provides a more definitive representation of vapor intrusion risks – eliminating uncertainty associated with short-duration ‘grab’ sampling and reducing bias of temporal variability on VOC concentrations.

Whether you are planning a vapor intrusion investigation, developing a remedial action workplan, or advising clients on sampling strategies, this guidance defines the state’s technical expectations and should be central to compliance-focused project planning.