IN 1991, THE U.S. Environmental Protection Agency (EPA) promulgated new criteria under Subtitle D of the Resource Conservation and Recovery Act (RCRA) that required municipal solid waste (MSW) facilities to provide a minimum of 30 years of post-closure care (PCC) after final closure. The federal criteria also allowed state regulators to extend or shorten the PCC time period as needed to provide for the protection of human health and the environment.
Regulators and other stakeholders have expressed a need for technical guidance to assist them in evaluating the feasibility of shortening or extending the 30-year PCC baseline at any particular site. To fill this need, the Environmental Research and Education Foundation (EREF), Alexandria, Va., contracted Columbia, Md.-based GeoSyntec Consultants to develop a peer-reviewed, performance-based methodology to evaluate environmental and health threats at landfills. The resulting approach, termed Evaluation of Post-Closure Care (EPCC), is an important compliment to EPA requirements for oversight of MSW landfills.
The goal of the EPCC project was to design a scientifically defensible, site-specific process to evaluate whether or not landfill leachate and gas continue to pose a threat to human health and the environment. Based on this evaluation, operational or monitoring elements — including leachate management, monitoring for landfill gas migration, groundwater monitoring, and maintaining the integrity of the final cover — can be discontinued or expanded.
To define the EPCC approach, GeoSyntec utilized a team of experts familiar with landfill engineering, operational and monitoring controls, and leachate and landfill gas characterization. The team of technical experts then worked closely with organizations such as the National Solid Wastes Management Association (NSWMA), the Solid Waste Association of North America (SWANA), the Association of State and Territorial Solid Waste Management Officials (ASTSWMO), and other stakeholders to develop consensus on the feasibility of the approach.
The EPCC guidelines describe approaches to gathering physical and chemical data at a landfill during PCC and procedures to evaluate that data, gauging the effectiveness of the landfill's measures to protect human health and the environment at the points of exposure.
The EREF approach can be used to evaluate when a closed landfill has successfully completed PCC and is ready to transition into non-regulatory custodial care and potential beneficial use.
The methodology advances the concept of long-term stewardship for landfills by providing clear guidelines for data collection and sound technical approaches for evaluating the potential dangers to human health and the surrounding environment. The approach:
facilitates improved allocation of resources;
endorses proactive management of those components that pose the greatest threat to the environment during the active life of the facility; and
ensures that future use of the land will be compatible with the surrounding area.
The EPCC approach is designed on a modular basis. Specifically, it includes five modules: one focusing on prerequisites and data requirements, and four PCC modules dealing with the elements described in Subtitle D (leachate, groundwater, gas and caps). The approach allows PCC to be evaluated on a sequential basis. Additionally, the modules can be used to conduct an element-by-element evaluation while the landfill is still operational to identify practices that can be optimized to reduce long-term potential threats.
These guidelines represent EREF's attempt to refine the post-closure regulatory process so as to focus resources on the aspects of the facility that need the most attention. As components of post-closure care cease to be needed (e.g., landfill gas generation declines to rates that no longer require active collection), requirements for that component can be eliminated or significantly reduced, redirecting the focus toward components that remain active.
The EPCC approach also provides a mechanism to evaluate environmental data to facilitate post-closure care decisions, including the optimization of various PCC components, up to and including terminating a component. Accordingly, the process is focused on defining long-term threats and encourages cost-effective application of resources to the components that require management consistent with long-term environmental stewardship.
The primary benefits of the EPCC approach include:
a defensible, systematic approach that facilitates the end of regulatory PCC and eases the transition to a non-regulatory care program, or “custodial care,” after the landfill is shown to be free of threats to human health and the environment at the points of exposure;
technical support in implementing proactive operational practices (such as bioreactors or alternative final cover technology), accelerating waste decomposition and stabilization, and reducing the long-term threat potential of landfills;
justification for optimization of resources during closure and PCC periods; and
a roadmap for environmental stewardship that helps return land to productive use while addressing community concerns regarding the evaluation of long-term threats to human health and the environment.
Overall, the EPCC approach encourages the proactive operation of active and closed landfills and ensures protection of human health and the environment prior to and during post-closure care.
Ed Repa is vice president — environmental programs at the Environmental Research and Education Foundation. Contact the author at email@example.com.
WANT TO KNOW MORE?
Copies of the report “Performance-Based System for Post-Closure Care at MSW Landfills,” which outlines the EPCC approach, are available by contacting Sarah Stancliff of the Environmental Research and Education Foundation at (703) 299-5139 or firstname.lastname@example.org. Technical questions regarding the project should be directed to Jeremy Morris (email@example.com) or Mike Houlihan (firstname.lastname@example.org) at GeoSyntec Consultants, Columbia, Md.