Winter 2023

Accounting for the Potential Impacts of Climate Change to Improve Remedy Decision-Making at Contaminated Sites

By Amy L. Dale, Ph.D.

In the United States, environmental remediation and corrective action at the federal level are often governed by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), the Resource Conservation and Recovery Act (RCRA), and – in the case of waste management units containing coal combustion residuals (CCRs) – the 2015 CCR Rule.  As part of the selection process for remedial and corrective actions, federal regulations require the evaluation of multiple alternative actions with respect to a wide range of factors, including the potential performance of each action and its impacts on the environment and human health.  Remedy decision-making must also consider economic factors (e.g., cost) and social factors (e.g., community acceptance and worker safety).

Green and sustainable remediation (GSR) incorporates sustainability more fully into the evaluation, selection, and implementation of remedial and corrective actions for contaminated sites.  A GSR-style assessment might include the carbon footprint of each proposed remedy, the potential impacts of the remedy on environmental justice communities, and strategies to reduce waste and reuse materials, but these factors are not required under RCRA, CERCLA, or the 2015 CCR Rule.

Researchers and regulators increasingly recognize the need to account for the potential impacts of climate change on proposed remedial and corrective actions at contaminated sites.”

Researchers and regulators increasingly recognize the need to account for the potential impacts of climate change on proposed remedial and corrective actions at contaminated sites.  The field of “sustainable resilient remediation” expands upon the classic GSR framework by including climate resilience as one of the key factors to consider during the evaluation of remedial and corrective actions.  In 2019, US EPA issued guidance for the site-specific evaluation of climate resilience at sites with impacted groundwater.  This guidance suggests that researchers identify the key climate-related hazards at these sites and assess the sensitivity of the remedy to each identified hazard (US EPA, 2019).

Many federal and state agencies, as well as other entities, have developed free and interactive web-based tools to facilitate screening-level assessments of climate-related hazards at individual sites, such as heat stress, flooding, storm surge, high winds, wildfires, and landslides.  However, in some cases, screening-level tools may not be available or have sufficient resolution to be applied with accuracy to a particular site (e.g., an embankment at a site is not shown on regional flood maps).  Therefore, in addition to performing a screening-level analysis, researchers should also identify any site-specific features that increase or decrease the vulnerability of the site to climate change.  When high accuracy is required, it may be possible to generate site-level projections using site-scale environmental models, driven by time series of future climate conditions generated by global climate models (GCMs).  Climate impact modeling requires expertise in the downscaling and bias correction of GCM outputs and should be done in consultation with experts.

By incorporating climate resilience into GSR-based frameworks for the evaluation of remedial and corrective actions at contaminated sites, we can ensure that selected approaches are not only safe and effective now but will remain so into the future.”

Once key climate-related hazards have been identified, researchers must evaluate the potential impacts of each hazard on the proposed remedies for the site.  This evaluation should include physical components of the remedy, such as primary system components (e.g., wells, pumps, subsurface barriers, and treatment systems), supporting components (e.g., monitoring equipment and electrical controls), and any critical site infrastructure (e.g., power lines and gas lines).  As part of this analysis, researchers should describe measures built into the system to increase its resilience, such as structural reinforcement, physical barriers, backup power systems, and secondary containment systems.  Additional factors of potential relevance include the adaptability of the proposed remedy, the technological complexity of the remedy, and the time required to achieve regulatory targets.  In general, a remedy that can be modified quickly and cheaply in response to changing conditions, relies on fewer vulnerable system components, and can achieve regulatory targets relatively promptly will have a higher climate resilience than one that adapts poorly to change, has greater complexity, and requires decades to reach remedial goals.

Once researchers have identified threats and assessed safeguards, a final judgement can be made regarding the overall resilience of the remedy and areas for potential improvement.  By incorporating climate resilience into GSR-based frameworks for the evaluation of remedial and corrective actions at contaminated sites, we can ensure that selected approaches are not only safe and effective now but will remain so into the future.  Choosing a climate-resilient remedy can improve its performance, increase its protectiveness towards human health and the environment, and decrease its long-term operation and maintenance costs.