Maryland’s municipal landfills produced roughly four times more carbon dioxide and methane over the past 15 years than the state Department of the Environment (MDE) previously estimated, according to a study released June 9 by the Environmental Integrity Project.
As reported by The Baltimore Sun, the errors—which were confirmed by the state—persist in greenhouse gas estimates dating as far back as 2006.
The environmental nonprofit’s modeling shows that solid waste landfills are Maryland’s greatest source of methane, pushing landfills ahead of the natural gas industry and agriculture as methane sources.
According to Ben Grumbles, the state’s secretary of the environment, MDE 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, reports The Baltimore Sun.
The report states that Maryland environmental officials had “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 percent of methane, but MDE mistakenly applied the inverse—resulting in a 90 percent reduction—for years.
The department plans to reinvigorate plans to update landfill regulations with a stakeholders meeting June 23. At the meeting, Maryland officials plan to discuss landfill gas capture and repair regulations that would put the state on par with California, which currently has the most stringent landfill gas regulations in the country.
“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.”