California State Water Board Announces Scoping Phase for New Vapor Intrusion Cleanup Requirement – Environmental Law


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On March 25, 2022, the California State Water Resources Control Board (State Water Board) issued a notice of public scoping meeting for a proposed change to its rules governing site cleanup. This amendment would establish “requirements for the investigation and assessment of steam intrusion at cleanup sites statewide.”

In recent years, guiding the California Vapor Intrusion has been in limbo. In February 2020, the Department of Toxic Substances Control and other state agencies released draft supplemental guidance to amend previous vapor intrusion guidance issued in 2011. A key change in the draft supplemental guidance of 2020 concerned the mitigation factors to be applied to the site sampling results during the assessment. potentially harmful vapor intrusion into buildings. The 2020 Draft Supplementary Guidelines have increased the stringency of the mitigation factor to be applied, setting a factor of 0.03 to be applied uniformly for screening of all buildings, regardless of their use. This draft additional guidance has still not been finalized, which has raised concerns about standards for vapor intrusion assessment and remediation. In many cases, when cleaning or refitting, the effect is that the strictest mitigation factor is applied – often at significantly increased cost.

The State Water Board is now proposing to insert its own standard into the mix. As described in the recently released advisory, the State Water Board’s proposal seeks to address vapor intrusion assessments “on a case-by-case basis” and indicates that the State Water Board is seeking a uniform standard to be applied in such assessments. The notice further describes that the proposed amendment “would establish a state policy for water quality monitoring that requires the use of a timely, consistent, and protective approach utilizing water-scale data. of the State to assess the risk of steam intrusion”.

At this point, as only a scoping meeting has been proposed, full details of the State Water Board’s proposed amendment are not yet available. Given the notice’s descriptions, the State Water Board may consider setting its own mitigation factor for cleanups under its jurisdiction. This could affect sites throughout California, with potentially substantial cost effects for cleanup and redevelopment projects.

The two scoping meetings, during which the State Water Board will receive feedback on its proposal, are scheduled to take place by videoconference on April 28, 2022. The State Water Board is also accepting written feedback until noon on May 9, 2022.

The content of this article is intended to provide a general guide on the subject. Specialist advice should be sought regarding your particular situation.


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