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Sampson County site ranks No. 2 among U.S landfills for methane emissions. Rotting food is part of the problem.


Sampson County site ranks No. 2 among U.S landfills for methane emissions. Rotting food is part of the problem.

Jan 25, 2023 | 6:00 am ET
By Lisa Sorg
Sampson County ranks No. 2 among U.S landfills for methane emissions. Rotting food is part of the problem.
Sampson County site ranks No. 2 among U.S landfills for methane emissions. Rotting food is part of the problem.
The Sampson County Landfill accepted 1.57 million metric tons of waste in 2021. That same year, the facility emitted more than 824,000 metric tons of methane, as measured by its carbon dioxide equivalent — ranking it second in the nation. The landfill has a methane collection system that also recovered more than 11,000 metric tons that year. (Photo courtesy of Cape Fear River Watch)

This is the first in an occasional series of stories about greenhouse gas emissions and their sources. View a slideshow of  emissions trends for municipal waste landfills that emit more than 100,000 metric tons of methane per year.

T wenty-five million tons of garbage is rotting in the Sampson County landfill: disposable diapers from Durham, moldy leftovers from refrigerators in Wake, face masks and old toothbrushes from Brunswick, and sundry flotsam from 44 counties statewide.

Over time, the detritus of our lives, particularly food waste, breaks down in the landfill and emits methane, a powerful greenhouse gas that ranks only second to carbon dioxide in driving human-caused climate change. 

Largely because of the sheer tonnage of decomposing trash, Sampson County ranks second in the nation in methane emissions: 824,568 metric tons of carbon dioxide equivalent, according to the 2021 EPA figures. Of the estimated 1,321 municipal solid waste landfills in the U.S., only a facility in West Palm Beach emits more, 1.01 million metric tons of CO2 equivalent.

A CO2 equivalent, or “CO2e,” converts different greenhouse gases, such as methane and nitrous oxide, to a common unit based on their global warming potential. 

Landfills that emit at least 25,000 metric tons of CO2e annually are subject to the EPA reporting requirement. But the Sampson County landfill’s sizable methane emissions are missing from the NC Division of Air Quality online inventory. So are similar reports for most of the state’s largest municipal solid waste landfills — known as MSWs for short — that have been required to provide that information since 2010 to the federal government. 

There are 43 permitted MSWs in North Carolina; of those, 37 reported their methane emissions to the EPA in 2020. However, only a quarter of them also sent that information to the state. Two smaller emitters, the Columbus County and Tuscarora Long-Term Regional Landfills reported to the DAQ, but weren’t required to file with the EPA.

(EPA has reports from 2021, but DAQ doesn’t; the comparison was made for the most recent year when both data sets were available.)

The lack of data on the state website is a feature, not a bug. Division of Air Quality spokesperson Shawn Taylor told Policy Watch that “while we encourage the practice, facilities are not required to include greenhouse gases in their emission inventories to DAQ.” That means the state database includes only methane emissions from facilities that voluntarily report this information. 

Nowhere on the DAQ website is there a link to the EPA database, known as FLIGHT, or a disclaimer to explain this significant data gap. And without knowing about the loophole, researchers, community groups, environmental advocates and even the media could assume, wrongly, that most North Carolina landfills don’t emit significant amounts of the damaging greenhouse gas — or even any at all.

In fact landfills are the third-largest direct source of methane in the U.S., according to federal figures. In North Carolina in 2021, MSWs sent 3.7 million metric tons of the greenhouse gas into the air.


Sampson County site ranks No. 2 among U.S landfills for methane emissions. Rotting food is part of the problem.
Map by Lisa Sorg, based on EPA FLIGHT data
T he data have never been posted on the state website in the 12 years since the EPA began requiring the reporting.

In 2008, the NC Environmental Management Commission held a public hearing about potential changes to greenhouse gas reporting rules. The EMC ultimately opted in November 2009 not to require MSWs to report methane and other greenhouse gas emissions to the Division of Air Quality, according to meeting minutes.

At the time, there were several valid reasons for this decision: North Carolina was in a severe budget crisis because of the 2008 recession. The state didn’t have the money to modify its reporting software to be compatible with the EPA’s.

“Although this would be optimal it’s not technically feasible because NC’s software will not be formatted like the federal electronic reporting software,” EMC meeting minutes read. “Substantial state resources would have to be invested to modify the system.”

The EPA had just issued a final rule on greenhouse gas emissions reporting, which the state believed was enough for it to use in climate change planning. Nor did North Carolina have a climate action plan in 2009 to “guide DAQ” in collecting the information, the minutes read.

However, in terms of climate change, 2009 looks nothing like 2023. Globally, concentrations of atmospheric methane from all sources are currently higher than at any time in at least 800,000 years, according to the Intergovernmental Panel on Climate Change. Extreme weather is now the norm, including in North Carolina, where there have been a dozen weather-related federal disaster declarations in the past decade.

“Methane is obviously one of the most critical pollutants driving the current warming,” Maggie Monast, chairperson of the EMC’s Air Quality Committee, said.

The state now also has a climate plan and a Climate Change Interagency Council. Gov. Cooper has issued several executive orders to address the role North Carolina plays in warming the planet. The state Greenhouse Gas Inventory estimates statewide emissions from many sources, including landfills.

That data are presumably based on reports filed with the EPA, but nowhere in the 84-page document does it explain why DAQ doesn’t collect the information. (A citation for the EPA data is buried in the document — in footnotes and links on Page 51.) Nor does the inventory break out any emissions by county, which would be helpful in pinpointing the sources.

Sampson County site ranks No. 2 among U.S landfills for methane emissions. Rotting food is part of the problem.

Monast was appointed to the EMC by Gov. Cooper in 2019. She said she was unaware DAQ didn’t require concurrent greenhouse gas reporting with the EPA. “I’m certainly interested in understanding the gaps and how the data can be improved,” Monast said.

The state’s Solid Waste Association chapter could not be reached for comment about their position on a new rule.

After Policy Watch asked about the gap in reporting requirements, Monast said she spoke with DAQ. While the EMC could independently pursue an updated reporting rule, that process can take two or more years, depending on the complexity of the issue and the level of public engagement. 

Instead, Monast said the state was willing to “bring the EPA data to a more prominent place” on the DAQ website. “That might the easiest path forward. That’s a reasonable next step.”

 Landfills by the numbers

800,000 – number of years since global atmospheric methane levels have been as high as they are now

25 million – tons of garbage in the Sampson County landfill, the top methane emitter in NC and second in the nation

828,568 – metric tons of methane emitted by the Sampson landfill, as measured in units of carbon dioxide equivalent.
Another 10,000 metric tons are emitted from Sampson’s former landfill, now closed.

2 million – tons of garbage in the Great Oak landfill in Randolph County, the second-highest emitter

162,452 – metric tons of methane emitted by Great Oak, as measured in a CO2 equivalent

3.7 million – metric tons of methane emitted by all municipal solid waste landfills in NC

43 — Number of permitted municipal waste landfills in NC

37 – MSWs in NC that report their emissions to the EPA

11 – MSWs in NC that voluntarily report their greenhouse gas emissions to the Division of Air Quality

0 – number of MSWs that are required to report their GHGs to the state

10 – number of MSWs emitting more than 100,000 metric tons of CO2e that are located within
predominantly low-income neighborhoods, communities of color, or both

54 — MSWs in NC that have installed some type of landfill gas capture system

3 million – number of metric tons of GHGs reduced or avoided by these systems in one year

Sources: EPA FLIGHT and landfill gas databases, DAQ solid waste and emissions inventories, 2020-2021, International Energy Agency

I f it weren’t for landfill gas collection systems, methane emissions would be even higher. 

The emission amounts reported to the EPA are the net, after subtracting the amount of methane collected and destroyed by landfill gas systems. Any methane that is collected but not destroyed and enters the air is counted, however. The amounts are also adjusted to reflect “soil oxidation,” an EPA spokesperson told Policy Watch, a term that refers to methane that is converted to carbon dioxide in the landfill’s soil cover.

The EPA tracks these landfill gas projects for each state. In the agency’s database of 124 MSW landfills in North Carolina, less than half — 54 — had methane capture system, as of 2020. Nonetheless, they reduced or avoided emitting 3 million metric tons of greenhouse gases that year. Many landfills use the gas to generate power onsite or plan to inject it into pipelines.

Another 69 landfills had no systems. In many cases, they are considered to have a low potential for methane capture. Suitability can depend on the age of the landfill — after 20 to 30 years, the amount of methane decreases — and the type of waste it contains.

One landfill — Orange County — shut down its capture system, which it operated in partnership with UNC, in 2018. After a series of equipment breakdowns, the university decided it was too expensive to run based on the amount of methane captured. It now flares the methane, converting it to carbon dioxide. That landfill sends 18,420 metric tons of greenhouse gases into the air each year, significantly less than a decade ago, but 50% more than when the system was operating, even sub-optimally, in 2016.

How to reduce your methane emissions? Eat your food.
Food waste is the most common material in landfills in the US, according to the EPA, making up about a quarter of solid waste. In 2018, 81% —20.3 tons— of household food waste wound up in landfills or incinerators, EPA figures show. Each year US food loss and waste holds 170 million metric tons of carbon dioxide equivalent greenhouse gas emissions — equivalent to annual CO2 emissions of 42 coal-fired power plants, according to the EPA, That doesn’t even include methane emissions from food decomposing in landfills.

To keep food out of the landfill and to reduce your greenhouse gas impact
* Plan meals and buy non-perishable items in bulk, which cuts down on emissions Fromm packaging
* Refrain from overbuying perishable items
* Freeze leftovers
* Compost unused food or discarded parts, if you have the space and means. Buy a small compost bin or subscribe to a curbside pickup service. You can donate compost to community gardens.