San Diego’s Landfills Are Leaking Planet-Warming Methane
Data from the San Diego Air Pollution Control District show landfills operated by local government and private operators have been emitting methane for years from leaky wells, tanks and hatches and improperly burning off the gas called flaring.
For years, San Diego’s landfills have been racking-up thousands of dollars in fines for leaking methane, a major cause of climate change, as operators struggle to contain it.
The planet-warming gas can trap heat close to the Earth’s surface 80 times better than carbon dioxide in a 20-year period. Governments everywhere are trying to reduce it, from the city of San Diego, which just dropped plans to cut 90 percent of landfill methane by 2035, to President Joe Biden’s Administration which announced a U.S. crackdown on methane during a global meeting of nations on climate change, according to the New York Times.
Data from the San Diego Air Pollution Control District show landfills operated by local government and private operators have been emitting methane for years from leaky wells and improperly burning off the gas called flaring, leaving them on the hook for thousands of dollars in fines from the local air pollution regulator.
Despite methane taking center stage globally, regulatory agencies and solid-waste experts acknowledge landfill gas leaks are expected to some degree.
“It’s like whack-a-mole,” said John Sepich, an engineer at Brownfield Subslab who used to work on San Diego County landfills decades ago. “Landfills are constantly settling (as waste breaks down). As they do, the cover breaks up, seals around the well need repair – it’s a constant maintenance issue.”
It’s also a question of size. Sycamore Landfill in Santee is one of the top 10 largest in the state, said Ryan Schauland, manager of greenhouse gas emissions quality assurance at California Air Resources Board, so it’s expected that it would emit some methane given its size.
“They all emit a little bit,” he said. “There’s no way around it, it’s not hermetically sealed.”
It’s also largely a question of what you throw in the landfill in the first place.
Methane is the second-largest source of greenhouse gas emissions in California and landfills are the biggest standalone source of that gas in the state. It’s a byproduct of rotting organic waste; think apple cores, banana peels and coffee grounds.
The best way to reduce methane is throwing that organic stuff somewhere else, typically by asking citizens to separate methane-making food waste from other trash and diverting it to composting sites. That’s not happening. But come 2022, governments and private trash haulers will have to figure out a way or face penalties under a new state law.
In the meantime, it’s the landfills and the companies that manage the methane taking the heat.
To understand why landfills are leaking methane, it’s important to know how they work.
At a landfill, haulers lay trash in layers called “lifts,” sometimes lining each one with clay or plastic sheeting that prevent fluids and gases from leaching into soils and the atmosphere. A system of pipes, typically thrust vertically into the many layers of trash with an opening at the top, capture gas all that rotting gives off. That captured methane can be reused and pumped into generators that make electricity, precisely what happens at the Miramar Landfill on Convoy Street, or burned off in the form of flaring. Gas from that Miramar Landfill powers almost 90 percent of the electricity needs of the Metropolitan Biosolids Center and the North City Water Reclamation Plant, according to the city’s website.
Beginning in 2016, the San Diego Air Pollution Control District, which regulates air pollution like cancer-causing air toxins, became the enforcer of state methane regulations on local landfills under a written agreement with the California Air Resources Board.
Inspectors drop-in on thousands of different pollution and methane emitters per year. Since 2017, operators of the Sycamore, Miramar, Otay and Jamacha landfills and private gas recovery companies had to pay thousands of dollars in violations for letting methane get away from the landfill beyond an allowable concentration, which is 500 parts per million volume. The way to think about that is out of a million cubic inches of air (its volume), 500 of those are methane.
The Miramar Landfill off Convoy Street, owned by city of San Diego, had at least six-related methane fines since 2017. Among them the city paid $1,600 in fines for wells leaking 17,500 parts per million volume for violations in April of 2018. There’s an open case against it for violations in November of 2019 for a well leaking methane at 8,662 parts per million volume. The city paid another $5,600 in August for at least 14 wells breaching the allowable methane concentration.
The city’s Environmental Services Department staff are “evaluating and will respond accordingly” to the violations, said Alma Rife, a department spokesperson, in an email.
In April of 2017, an inspector found the gas system at Sycamore Landfill in Santee, operated by Republic Services (a private, global solid waste disposal company), had repeated leaks of methane above the state-allowed level at four different wells. That resulted in a $9,600 fine.
In May of 2020, that same landfill had another three wells emitting above the methane limit resulting in another $8,000 worth of fines.
Neil Mohr, general manager at Republic Service’s San Diego branch, said in an email that those emissions violations “were addressed and corrected immediately” and that the company is building-out the gas recovery system.
“Sycamore Landfill expanded its gas collection system this fall with construction of additional wells completed in just the last few weeks,” Mohr said.
The County of San Diego, which owns the now-closed Jamacha Landfill in Spring Valley, contracts with an independent engineering firm to maintain and operate the methane gas system, according to spokeswoman Donna Durckel. The firm, SCS Engineers Environmental Consultants, declined a request for an interview.
The Air Pollution Control District fined the county $1,500 in May for improperly burning-off methane gas discovered during an inspection about a year prior and other violations. Durckel said an automatic shutdown device, designed to stop the flow of landfill gas to the flare, malfunctioned. SCS Engineers had to pay the fines, under its agreement with the county, and added real-time notification systems to monitor the gas, Durckel wrote in an email.
Otay Landfill in Chula Vista, also operated by Republic Services, has an open case against it from Aug. 3 for multiple violations including methane emissions exceeding state standards from five different wells. That same landfill paid another $2,000 in December of 2019 for methane leaking from the surface of the landfill at a concentration almost 21 times the permitted amount.
Sepich, a landfill expert, said it’s easy to breach that limit despite an operator’s best efforts, especially because landfills are constantly shifting as trash settles.
“It’s a balancing act,” Sepich said.
The district does routine inspections of landfills, generally taking measurements by hand at the surface. So it’s a good way to double-check whether its wells are emitting legal concentrations of methane. But as far as judging how much the landfill emits as a whole is harder to gauge.
The California Air Resources Board recently completed a novel study to answer just that. Researchers wanted to measure landfill methane from in the atmosphere, so they slapped methane sensors onto an airplane which then circled the air above landfills higher and higher into the air, as if it were tracing a giant tin can.
The results produced more detailed estimates of a landfill’s methane profile, measuring methane in kilograms emitted per hour. It’s not unusual for a landfill to emit about 1,000 kilograms per hour, Schauland said, but if a landfill is emitting 3,000 to 4,000 kilograms per hour — that’s when CARB starts to raise an eyebrow.
Methane the aircraft measured around the Sycamore landfill reached a maximum of about 996 kilograms per hour. That’s not too bad, considering how large that landfill is. Miramar landfill was the closest eyebrow-raiser, emitting a maximum detected amount of 1,564 kilograms of methane per hour. Otay measured the least, emitting a measured 130 kilograms per hour.
According to a 2015 survey by the county, Sycamore and Otay landfills receive most of the county’s waste. And they’re filling up fast. Officials have been pushing the state to raise the height of the Miramar Landfill so it can take more waste.
The city of San Diego’s new draft Climate Action Plan released last week targets capturing 90 percent of the gas from its landfills by 2035. About 74 percent is captured now, according to the latest report on its plan.
Landfills are supposed to cut 75 percent of methane-producing organic waste by 2025 under state law.
While the burden currently falls on operators, some are trying to educate the general public on ways to reduce the amount of food waste that ends up at the landfills. Groups like San Diego Food System Alliance, while not focused on polices to reduce methane specifically, offer materials and courses to educate the public on how to cut food waste.
“In our region cities are looking around for where we can process all this food waste because we don’t have many facilities,” said Geertje Grootenhuis, program director of wasted food prevention. “The burden gets pushed over to waste haulers… There’s definitely movement happening but we still have a net deficit ability to process organic material.”