Transitioning from Active to Passive Care at Municipal Landfills: Full-Scale Site Evaluations using the EPCC Methodology
Investigators: Geosyntec Consultants
The Subtitle D regulations governing municipal solid waste (MSW) landfills reference a 30-year post-closure care (PCC) period, but also mandate that PCC be continued until it is demonstrated that ending care does not pose a threat to human health or the environment (HHE). The performance-based Evaluation of Post-Closure Care (EPCC) methodology provides a modular approach for sequentially evaluating the four primary post-closure care (PCC) elements (i.e., leachate management, landfill gas management, groundwater monitoring, and cover maintenance) in terms of ‘functional stability,’ which describes a closed landfill that does not present an unacceptable threat to HHE in the absence of active care. Functional stability implies residual leachate and gas emissions can be managed using passive measures such as windmills, wetlands, biofilters, or methane oxidation caps (biocovers). After functional stability is demonstrated, a mechanism for confirmation monitoring is suggested, ultimately allowing transfer of responsibility from a regulated PCC program to a custodial care program.
The EPCC methodology is almost eight years old and much has been learned since publication in 2006, not least in terms of simplifying and adapting its application to address different technical and regulatory objectives. The overall objective of the proposed project is to illustrate how updated EPCC methodology components can be applied to progressively demonstrate step-down reductions in PCC, starting with fully active controls and ending with fully passive measures representing a de minimis level of care that meets sustainability objectives, can be provided under a non-regulatory custodial care program of land management, and facilitates beneficial reuse of the site. This will be achieved by performing a series of retroactive data evaluations at a case study landfill that has completed nearly 20 years of PCC and achieved fully passive residual controls. Specific objectives include:
- Updating the ‘EPCC tool box’ to provide additional guidance on methodology application, including what data are required and how to evaluate the data;
- Illustrating the simplicity and flexibility afforded by methodology application at different stages of the post-closure lifecycle (i.e., early, middle, and end of PCC);
- Quantification of the environmental implications of decisions made at each stage; and
- Demonstrating that desired outcomes from the methodology are relevant and achievable