When Landfills Run Hot: Why Leachate Strategy Matters

Heat is normal in a landfill. Excess heat is not.

As waste decomposes, microorganisms naturally generate warmth. When temperatures move well beyond the normal biological range, however, the effects can spread quickly through a landfill system.

Methane production can decline. Settlement can accelerate. Odors can change. Leachate can become stronger, harder to treat and significantly more expensive to manage.

For owners and operators, that last point deserves particular attention.

Much of the public discussion around elevated temperature landfills (ETLFs) centers on heat and landfill gas. Both matter. But in day-to-day operations, leachate can become the problem that consumes storage capacity, narrows disposal options and drives costs.

Virginia is seeing that challenge play out in real time.

At the Shoosmith Landfill in Chesterfield County, Virginia, Department of Environmental Quality (DEQ) records show estimated leachate generation of approximately 390,000 gallons per week. DEQ also reported that pump-and-haul costs had reached approximately $90,000 per week based on estimates provided by the facility.

Those numbers illustrate the larger issue. When leachate quantity and strength change together, a disposal approach that once worked can become difficult to sustain.

The opportunity is to recognize that change earlier, understand the chemistry and build treatment flexibility before the available options narrow.

Municipal solid waste landfills naturally generate heat through biological decomposition.

The U.S. Environmental Protection Agency (EPA) identifies 32°C to 55°C (90°F to 131°F) as a range associated with normal landfill operation. Temperatures from 55°C to 63°C (131°F to 145°F) can indicate heat-generating chemical reactions. Above 63°C (145°F) methane generation slows and above approximately 72°C (162°F) biological activity can become minimal.

The distinction between an ETLF and a landfill fire is also important.

EPA describes ETLFs as landfills that exhibit temperatures above regulatory thresholds because of abnormal chemical reactions within the waste mass. Surface landfill fires typically depend on available oxygen and affect a more localized area. ETLF conditions can develop deeper within the waste mass and require a different diagnostic and management approach.

Reactive waste streams can contribute. EPA identifies ashes and dusts as well as aluminum, iron and steel production by-products among waste types known or suspected to be associated with elevated temperatures. Moisture also matters. One common observation at ETLFs is a wet affected area, highlighting the importance of drainage and liquids management.

That means temperature should not be viewed in isolation.

Operators should look at the whole pattern: temperature, gas composition, settlement and changing liquids behavior.

Common indicators identified by EPA include:

• Gas temperatures above 55°C (131°F)
• Methane below approximately 40%
• Carbon dioxide above approximately 50%
• Increasing carbon monoxide, hydrogen or ammonia
• Sudden settlement
• Strong or changing leachate
• Noxious odors

The value lies in the trend. A steadily changing well can tell a more useful story than waiting for one measurement to cross a regulatory threshold.

Leachate already presents a demanding treatment challenge under normal landfill conditions. Subsurface elevated temperature conditions can add another layer of variability.

EPA notes that ETLFs can generate strong leachate and leachate seeps or outbreaks. Virginia records from Shoosmith show what that can mean operationally.

DEQ reported that the landfill was generating an estimated 394,579 gallons per week, or approximately 1.49 million liters per week, based on information submitted by the facility.

The comparison with historical assumptions is striking.

The same DEQ record states that the facility’s earlier financial-assurance estimate was based on 14,423 gallons per week of leachate generation. DEQ contrasted that with the later estimate of nearly 395,000 gallons per week.

That is why liquids management belongs near the center of ETLF planning.

Once volume increases or chemistry becomes less compatible with a receiving wastewater system, operators have fewer easy choices. Storage fills faster. More trucks may be needed. Treatment capacity becomes harder to secure and the economics can change quickly.

Publicly owned treatment works (POTWs) can be an important part of a landfill leachate strategy. They are not an unlimited outlet.

A POTW must protect its own biological processes, equipment and discharge permit.

At Shoosmith, Chesterfield County suspended the landfill’s industrial wastewater discharge permit in 2024. County records state that the landfill subsequently began hauling collected leachate off-site for treatment.

The case offers a practical lesson without requiring every landfill to share the same chemistry or circumstances.

That makes contingency planning important even when the current arrangement is working well.

What happens if acceptance limits change? What happens if pretreatment performance deteriorates? Where does the liquid go while a permit issue or treatment problem is resolved?

Those questions are easier and less expensive to answer before trucks are already lining up.

Virginia’s regulatory direction reflects that need for earlier action.

The Virginia Waste Management Board published Early Detection and Management of Elevated Temperature Landfills in the Virginia Register of Regulations on July 13, 2026. The comment period closed on August 12, 2026, so the effective date is now pushed ~30 days while the DEQ considers the comments and determines next steps. Its stated purpose is to support early detection through proactive monitoring, appropriate financial assurance and corrective actions that limit additional environmental impacts.

Existing Virginia regulations already require owners or operators of solid waste disposal facilities to develop gas-management plans and conduct landfill gas monitoring. At a minimum, as written, the regulation requires quarterly gas monitoring, with more frequent monitoring possible where results indicate migration or accumulation concerns.

The direction is clear: use monitoring to recognize a changing condition early enough to manage it.

Virginia is also reconsidering how landfill financial assurance accounts for these conditions.

The 2026 budget directs DEQ to revise its financial-assurance regulations so that funding is sufficient for landfill caps, leachate management, gas collection and management as well as other work required to protect health and the environment.

Importantly, the language specifically requires financial assurance to address “the possibility of an elevated temperature landfill.”

For operators, that creates a financial reason to understand liquids risk before an ETLF develops.

If a financial-assurance model assumes one leachate volume or one disposal cost while actual conditions require something very different, the gap can become substantial.

Virginia has committed $10.627 million in FY2027 to support operations, environmental monitoring, leachate testing, collection, hauling, treatment, gas management and closure work at Shoosmith Landfill.

Testing is already influencing how the long-term treatment problem is being framed.

In July 2026, Chesterfield County reported that consultants were testing leachate from parts of the landfill that were not generating elevated temperatures to determine whether those flows could meet the county’s industrial discharge requirements with less treatment or potentially without pretreatment. DEQ Director Mike Rolband also discussed the possibility of separating flows and applying different treatment approaches.

That is an important shift in thinking.

It moves treatment away from the assumption that every gallon should receive the same process.

Where characterization supports it, separating streams by chemistry or treatment requirement may allow operators to focus the most intensive treatment where it adds the most value.

The principle is simple: know the water before designing the treatment.

For high-strength leachate, a treatment train may include equalization, physical solids removal and biological treatment followed by polishing.

A membrane bioreactor (MBR), for example, combines biological treatment with membrane separation. Its success depends on keeping a healthy microbial community capable of handling the incoming load.

That matters because landfill leachate can be variable.

Rather than asking only how much biological treatment capacity a site can build, it is useful to ask a different question:

If inhibitory compounds, changing loads or temperature are limiting the microorganisms responsible for treatment, simply increasing tank volume may not address the root cause.

Characterization and treatability testing can help operators identify:

• Constituents affecting biological performance
• Changes in ammonia and organic loading
• Solids or scaling risks
• Potential membrane-fouling conditions
• The value of pretreatment
• Whether separate streams need different treatment
• PFAS concentrations and potential management options

That information turns treatment design from an assumption into an engineering decision.

Virginia’s PFAS requirements make characterization even more relevant.

Under § 62.1-44.34:32 of the Code of Virginia, POTWs must require quarterly PFAS discharge monitoring for an initial one-year characterization period from specified industrial users. This includes landfills where the POTW has a reasonable basis to believe the facility is a source of PFAS.

If PFAS is detected above the method detection limit during the initial year, quarterly monitoring continues. The POTW may reduce monitoring to annually where results meet the conditions established in the statute.

The law also identifies centralized waste treatment facilities. Monitoring is based on EPA Method 1633 or another EPA-approved method allowed by Virginia DEQ.

These requirements do not create a universal PFAS discharge limit for landfill leachate.

What they do create is visibility.

Receiving facilities will have more information about PFAS in the waste streams entering their systems. For landfill operators, understanding that chemistry before a receiving facility raises the question is increasingly useful.

One approach Onterris is developing for challenging wastewater is NanoSORB™, an adsorbent media designed for use within activated sludge, sequencing batch reactors, and membrane bioreactorssystems.

NanoSORB introduces specialized media into the biological treatment process, where it becomes incorporated into biological floc and provides adsorption capacity for PFAS. Onterris describes the technology as a way to integrate PFAS capture into existing biological treatment infrastructure while concentrating captured PFAS into a small solids stream for subsequent management.

The important idea is bigger than one technology.

Biological treatment is not simply a box in a process diagram. It is a living system. Protecting that system from changing feed conditions can be as important as adding more capacity.

That is especially relevant for ETLF leachate, where the influent itself may continue to change.

Any enhanced biological approach should therefore be validated against site-specific chemistry through bench or pilot testing before full-scale implementation.

For landfill owners and operators, the most useful response to ETLF risk starts before an emergency.

1. Watch the trend, not only the threshold.
   Bring temperature, methane, carbon dioxide and other indicators together. A pattern of change can provide more useful warning than a single measurement.
2. Characterize leachate early.
   Develop a baseline and understand how flow, ammonia, solids, organics, metals and PFAS change over time.
3. Test before scaling.
   Treatability testing can expose inhibition, fouling or process limitations while there is still room to adapt the design.
4. Plan for an outlet to change.
   A POTW or third-party processor may remain part of the long-term strategy. It should not be the only strategy that has been considered.

Elevated temperature conditions connect issues that are often managed separately.

Heat affects gas. Gas conditions can signal changing biology. Changing conditions affect liquids. Liquids affect wastewater treatment and wastewater treatment affects cost.

The operators who connect those dots early have more choices.

They can respond while conditions are still manageable, use data to direct capital toward the right treatment steps and build a liquids strategy that is less dependent on a single outlet.

That is a practical path forward for both planet and progress.