Evaluating Conditions of Landfills for the Post-Closure Care Period

As you know, RCRA Subtitle C hazardous waste management regulations require a post-closure care period for certain hazardous waste treatment, storage, and disposal facilities. These regulations also specify post-closure care activities. What you may not know is that the post-closure care period can differ in duration from the standard 30-year period.

For instance, while most facilities are approaching the end of the first post-closure care period, some facilities may need more post-closure care depending on the conditions at these facilities. In this article, we review the guidelines and recommendations set by the Office of Resource Conservation and Recovery in evaluating the conditions at each facility and creating a closure plan. We will give an outline that will help you decide whether you can reduce the post-closure care time requirements or whether you will need to plan for an extension.

Creating a post-closure plan

Land disposal units such as landfills, land treatment units, and surface impoundments need post-closure care when they leave hazardous waste in place after closure. Post-closure care also applies to some non-land-based units such as waste containment tanks or buildings. These measures help protect human health and the environment.

Post-closure care activities make up two responsibilities: monitoring and reporting as well as supporting the integrity of the waste containment systems¹. The care period begins after a unit’s closure and lasts for 30 years. Regulations give authorities the ability to adjust the length of the post-closure care period depending on the conditions at the site.

Post-closure care and altering the default duration

While the post-closure care period is set to 30 years by default, inspection of site-specific conditions can lead to changes to that timetable. If 30 years is not enough to remove all potential threats to human health and the environment, then authorities will ask for more time dedicated toward post-closure care. There are also situations when a full 30-year post-closure care period is not necessary. Reviews are done on a case-by-case basis that ultimately determine the necessary length of the care period. There are two scenarios:

While unlikely, you could theoretically shorten the post-closure care period when “the reduced period is sufficient to protect human health and the environment (e.g., leachate or ground-water monitoring results, characteristics of the hazardous wastes, application of advanced technology, or alternative disposal, treatment, or re-use techniques indicate that the hazardous waste management unit or facility is secure).” The burden of evidence to request a shorter post-closure term will be high.

Often, you may need to extend the post-closure care period when “the extended period is necessary to protect human health and the environment (e.g., leachate or ground-water monitoring results indicate a potential for migration of hazardous wastes at levels which may be harmful to human health or the environment).”

There are more than half a dozen criteria for evaluating the condition at the facility.

Criteria for evaluating and altering the post-closure care period

Here we outline the various criteria used to evaluate a facility’s condition during the post-closure care period and create a closure plan, along with the associated questions asked.

Waste treatment: Were all the wastes pre-treated according to treatment standards of the Land Disposal Restriction (LDR) program? Does the unit have wastes that were placed on the land prior to the effective dates of the LDR rules?²

Nature of Hazardous Wastes Remaining in the Unit: What is the degree of risk (e.g., exposure pathways, probability of exposure) presently associated with the wastes in the unit? Are these wastes highly toxic? Do they degrade into toxic materials? Is the waste in a stable state? Are there indications that the waste may become unstable?

Unit Type/Design: Does the unit meet the technology requirements (e.g., double liners, leachate collection system)or was the unit already in existence at the time these requirements were issued and closed before retrofitting?

Leachate: Will the integrity and functionality of the leachate collection system, leachate generation rate, and leachate quality remain adequate to prevent harm to human health or the environment in the absence of post-closure care? Can a statistical analysis show that the leachate will not pose a threat to human health and the environment? Can the leachate collection system be shut down without posing a threat to human health and the environment?

Integrity of Cover System: Was the cover system designed to minimize migration of water into the management unit and to prevent contaminants from escaping into the environment? Has there been testing to find any necessary damage for repair? Have these tests included differential settlement, problems with cover integrity (cracks, burrows, etc.), cover drainage, and the drainage system? Will the cover persist without long-term care of the vegetation? What are the minimum maintenance requirements to maintain cover system integrity?

Other criteria include groundwater inspections, siting and site geology/hydrogeology, the facility’s history, gas collection system integrity, long-term care requirements, timing, the state of the post-closure plan, public participation, and financial assurance requirements. When evaluated together, authorities can decide to shorten or extend the post-closure care period.