In a move that should not come as a great surprise, on December 7, 2016, U.S. EPA published a final rule which added a "subsurface intrusion” or “SsI" component to CERCLA’s Hazard Ranking System (HRS). More specifically, SsI can include either groundwater or vapor intrusion although vapor intrusion is the much more common exposure pathway. The new rule, which can be found here, will become effective within 30 days of publication in the federal register. According to U.S. EPA Waste Chief Mathy Stanislaus, the new rule expands the types of sites that be assessed by U.S. EPA to now include sites that solely have SsI issues, as well as sites that have SsI issues that are coincident with a groundwater or soil contamination problem.
The final rule is substantially similar to the draft rule but does have minor adjustments that were made in response to comments which U.S. EPA contends will better “help refine the mechanics of assigning an HRS site score.” Importantly, the new rule doesn’t change the existing HRS cutoff score of 28.5 for a site to qualify for listing on the NPL, nor does the new rule apply to sites that are already on or proposed to be listed on the NPL.
Industry groups and the Department of Defense had objected to the draft rule, and it is unclear whether the new rule will be retained or modified under the incoming Trump administration. We will continue to track this and other rulemaking efforts on the part of U.S. EPA as the administration continues to transition.