Maryland landfills produced 4 times more greenhouse gases than estimated by the state over the past 15 years

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Maryland’s municipal landfills have produced about four times more carbon dioxide and methane over the past 15 years than the state Department of the Environment previously estimated, according to a study released Wednesday by the Environmental Integrity Project and confirmed by the state.

The state’s mistakes, largely errors of arithmetic, persist in greenhouse gas estimates dating back as far as 2006.


The environmental nonprofit’s modeling shows that solid waste landfills are Maryland’s greatest source of methane, a climate change-causing gas that packs a greater punch than carbon dioxide, but lingers in the atmosphere for a much shorter duration. That pushes landfills ahead of the natural gas industry and agriculture as methane sources.

Maryland Secretary of the Environment Ben Grumbles said Wednesday that his department agrees with the report’s findings and has corrected the mistakes.


“There’s human error, and just given the comprehensive nature of our economy-wide, statewide modeling and emissions inventories, there can be mistakes that are carried on,” Grumbles said.

The biggest emitters are Prince George’s County’s Brown Station Road Landfill, Washington County’s Forty West Landfill and Baltimore City’s Quarantine Road landfill.

The report says that Maryland environmental officials initially miscalculated because they excluded five dumps, some of which have stopped accepting waste but continue to emit gases, and because they drastically overestimated the role of a process called surface oxidation in blocking the release of gases from underground.

The nonprofit researchers said the biochemical process, which takes place at the surface of landfills, removes about 10% of methane, but MDE mistakenly applied the inverse — a 90% reduction — for years.

The miscalculation doesn’t necessarily deal a blow to MDE models that predicted earlier this year that the state could reduce its output of greenhouse gases 50% from 2006 levels by 2030, because the 2006 baseline is affected, too. But it does place more weight on addressing landfill emissions, Grumbles said.

The department plans to reinvigorate plans to update landfill regulations with a stakeholders meeting June 23.

“[The report] has an impact on the urgency and the importance of moving forward with the regulatory approach with the larger landfills and also looking at incentives for more leak detection and repair of the landfills. And also redoubling our efforts on recycling and waste diversion,” Grumbles said.

Ryan Maher, an Environmental Integrity Project attorney who co-authored the report, said he initially noticed a problem with the state’s data when he saw a landfill listed that simply didn’t exist.


“I was looking for a landfill on Google Maps, and could not locate it for the life of me,” he said. “I contacted the county. This was supposed to be a public landfill, and they said, ‘We don’t have a landfill by that name.’”

Upon closer inspection, he discovered the more significant problems.

“It’s funny,” Maher said. “My job is to reduce methane emissions and now I’ve quadrupled them.”

The study recommends several strategies for reducing the impact of landfills and improving future estimates, including relying on more direct measurement techniques, such as drone studies, rather than statistical modeling.

The state also should set new rules for landfills, the Environmental Integrity Project said.

The best in the country are in California, where all landfills that produce a certain level of gas must install a gas collection and control system, according to the nonprofit. If those same rules, created in 2010, were applied in Maryland, 28 of the state’s 40 municipal solid waste landfills that produce gases would have to install systems.


MDE also would do well to reconsider how much gas is required to produce a flare, given updated technology, the environmental group said. That could rope in as many as 38 of the landfills, according to the researchers.

Currently, 21 Maryland landfills operate control systems, with varying degrees of efficiency, the report said.

In Baltimore County, officials recently announced they’d capture the methane produced at the Eastern Sanitary Landfill and use it to create energy.

The state is aiming to propose its new regulations before the end of the year, Grumbles said, and meet with the public, stakeholders and county officials in June. At the June meeting, Maryland officials plan to discuss landfill gas capture and repair regulations that would put the state on par with California, Grumbles said.

“We know there will be discussions about upfront costs for the controls and increased reporting and leak detection and repair,” Grumbles said. “We understand that, particularly for the smaller landfills. But we also know that there’s a cost to inaction.”

The report also recommends that MDE encourage counties and private companies to invest in waste diversion, through composting facilities and anaerobic digesters. Food scraps, yard waste and paper products account for about 26% of the waste going into Maryland landfills, and produce a large amount of methane.


Trash incineration, another way to divert waste, should not be considered a meaningful alternative to landfills, the Environmental Integrity Project report states. Not only does it also produce carbon dioxide, but burning trash can create damaging air pollution, releasing neurotoxins such as lead and mercury.