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San Diego County’s Methane Problem Visible For First Time

A system of underground pipes collects gas at Miramar landfill, but not all of it, March 2016.
Megan Wood
A system of underground pipes collects gas at Miramar landfill, but not all of it, March 2016.

San Diego County’s Methane Problem Visible For First Time
For the first time, it’s possible to visualize where powerful, invisible methane gas hovers over the landscape of San Diego County.

This is KPBS Midday Edition. I'm Maureen Cavanaugh. Do you live in one of San Diego's methane hotspots? Now you can find out inks to San Diego State researchers. By taking a level they were able to find leaks including somewhere the gas measured many times what's normal for the city. Ingrid reports. Methane is a bad actor, it holds keep close to the earth, warming the planet into a less hospitable place. San Diego State biology professor Chun-Tai Lai drove a van around the western part of the county analyzing for methane. Landfills are known to be a source because writing material creates a gas. He says they were surprised. We have seen methane levels as high as 15 times the ambient level. That was near the oh tiny in Chula Vista. Large circles near La Jolla represent another hotspot. We believe this is impact from Miramar landfill. We pick up a large signal here. Along 52, we continue to pick up this elevated methane levels. At Miramar landfill, deputy director Mike Thompson admits the city's own reports show this place is the largest methane admit -- emitter in San Diego County. The way the government make some estimate pollution exaggerates a problem. We just pulled up a life magazine from 1958, you can still read the cover clear as day. It's not decomposing nearly as fast as everyone thought it would. It's because it's so dry. Plus Thompson says, a system of pipes buried in the field sucks up the gas underground. We do have an active landfill gas control system. We are collecting the mass majority. The county air pollution control agency regularly cites the land though for methane coming up through cracks in the dirt. Sometimes it measured 2000 ppm, four times the legal limit. There seems to be a disconnect in what the city is saying. It says its omissions are lower than indicated in its own reports, it also says Senior mechanical engineer Ray Purtee says each time inspectors look for methane they find leaks over the limit. We might find 20/400 acres in one quarter. We might find 90/400 acres and a quarter. There is another sign that the gas from the landfill would be trailing West all the way to La Jolla to the La Jolla's Scripps Institute of Oceanography. We are measuring methane from an analyzer that's drawing near from the pier. They frequently detect methane. The highest value is when went the wind is out of the east. That points right at the Miramar landfill. We don't know that it's coming from there, but that is the number one suspect. His colleague says it's critical to get an accurate measurement of the amount of methane coming from the landfill. Local pipes leading to household stoves and heaters. San Diego has a climate action plan, we are quite progressive in that regard. It must be right. Measuring what's appearing in the atmosphere compared to what people say they're a meeting is often quite different. Addressing emissions in San Diego is going to require an accurate count of methane. While beyond the first snapshot provided by the San Diego State researchers. They would be the first to say that. I'm Ingrid low back -- To view an interactive map go to our new We will check in with some voters in Council District 9 and examine the concept of academic profiling. It's 12:31 and you are listening to KPBS Midday Edition .

For the first time, it’s possible to visualize where powerful, invisible methane gas hovers over the landscape of San Diego County.

Researchers have identified dozens of methane hotspots, including a series of hits near the Miramar landfill, with the gas apparently drifting to the end of the pier at La Jolla’s Scripps Institution of Oceanography, where a different group of scientists has an air intake connected to some of the world’s most sensitive atmospheric analyzers.


“Any time we go by Miramar from any direction, we pick up something,” said Chun-Ta Lai, a San Diego State University associate professor of biology who studies greenhouse gas emissions and led the research here. The higher methane levels continued along state Route 52.

The emerging sketch of the gas is important because escaped methane is a bad actor. It holds heat close to the Earth, warming the planet into a less hospitable place, though the concentrations are not toxic for people.

The research is a collaboration among researchers from San Diego State University, the University of California Irvine and the University of Utah. They drove specially equipped vans around each region, drawing in air and simultaneously analyzing it for methane.

The levels near La Jolla were elevated, but even higher were levels of the gas found near the Otay landfill in Chula Vista, with a plume leading west.

The flow of air west from the landfills may surprise Southern Californians accustomed to a prevailing breeze from the ocean. But in the cool of the night, the scientists say, that familiar ocean breeze actually reverses. Later, after the sun rises, it reasserts itself.


When he was gathering his air samples in the Ford Transit Connect van, Lai drove most of his research runs at night, the time he said when the air is calm.

He shared the data, which has not been published, with inewsource, which produced an interactive map.

(Parallel research conducted by the UC Irvine team across the Los Angeles basin appeared in the Journal of Geophysical Research: Atmospheres in February.)

Professors Ralph Keeling and Ray Weiss, both geochemists at Scripps Institution of Oceanography, March 2016.
Megan Wood
Professors Ralph Keeling and Ray Weiss, both geochemists at Scripps Institution of Oceanography, March 2016.

At Scripps Institution of Oceanography, which was not involved with Lai’s research, scientists also pick up “sources of methane quite near” the UCSD marine institution, said Ralph Keeling, a professor of geochemistry. “The highest values we see are when the wind is out of the east, and that points right at the Miramar landfill.”

There is no complete analysis at this point, he said. But “that is suspect No. 1.”

The landfill lies 6.1 miles from the pier, as the crow flies.

The methane Lai found is not likely to directly harm people. For the most part, it does not contain the foul-smelling chemicals that so bothered residents of Porter Ranch in Los Angeles County when a Southern California Gas well failed there recently, and the levels are too low.

The harm instead is to the environment, and possibly to San Diego’s ambitious Climate Action Plan. The plan commits the people of San Diego to reducing greenhouse gas emissions 60 percent below what would be predicted for 2035. It goes beyond the ambitions of most cities. San Diego’s plan aims for reductions on the order of what scientists say will actually be necessary to keep climate change in check. Plus it’s legally binding.

But it’s not at all clear that San Diego is accurately counting its methane emissions.

When landfills report methane to government agencies, they often use estimates, not actual measurements.

inewsource is an independent nonprofit dedicated to providing in-depth, data-driven journalism on the web, radio and TV.

The Miramar landfill is the largest emitter of methane in San Diego County, by its own account. Because of that the city has no choice but to sharply reduce emissions there to meet milestones under its plan.

Yet city officials in charge of the landfill could not say how much methane is being released from it. They could not say who provided baseline figures about the landfill’s emissions to the drafters of the city climate plan. And they could not say by how much those emissions will be reduced to comply with the plan.

Ray Purtee, a senior mechanical engineer, said the city contracts with a company that measures methane near ground level four times a year, walking a serpentine pattern across 400 acres. The contractor looks for cracks where methane flows out and concentrates at higher than 500 parts methane per 1 million parts air. The contractor always finds such places.

“We might find 20 in one quarter, we might find 90 in a quarter,” Purtee said.

Records show the landfill and its related contractors have been cited numerous times by the San Diego County Air Pollution Control District for uncontrolled escapes of methane from underground where garbage is rotting, sometimes sending forth streams of gas through cracks at more than 2,000 parts per million, four times the legal limit.

Whether it’s the city, which owns the landfill, that finds the crack, or the county, which enforces air pollution laws, earthmovers then mound up soil on the bleeding cracks and the ground is remeasured.

Yet the search is for these leaking cracks, not for how much total climate-changing gas is escaping.

This lack of data has become something of a cause for Ray Weiss, who is also a geochemist at Scripps. From laboratories there, he monitors levels of methane measured at the end of the pier, along with dozens of other climate-changing gases from monitors around the globe.

“When we measure what appears in the atmosphere compared to what people say they are emitting, it is often quite different,” Weiss said.

“You don't want to discourage somebody who is doing something important for the environment,” Weiss said, referring to the San Diego Climate Action Plan. “On the other hand, you want it to work, and the climate in the end doesn't really care what we do politically, or what we say we are doing. It only cares what we actually do. So there is a real need for independent verification as we embark on reducing our greenhouse gas emissions.”

This is especially true for methane, because in the short term, it is 84 times worse for the atmosphere than carbon dioxide.

Some city officials maintain that, rather than being undercounted, methane is being over counted from Miramar. Methane gas forms as natural materials decompose in moisture and without oxygen. Mike Thompson, deputy director of the San Diego Environmental Services Department, said that just isn’t happening as fast as federal guidelines presuppose in dry Southern California.

“We just pulled up a Life magazine from 1958, and you could read the cover as clear as day,” he said.

But in places where sophisticated measurements of the air near landfills have been carried out, such as in Germany, they’ve found estimates are too low, sometimes by a factor of two.

The only way to eliminate the methane made vivid on the new map of Lai’s data, said Nick Lapis, is to stop throwing food and other live material in the garbage.

“There is no excuse in 2016 to landfill organic waste. We have better things to do with that material,” he said.

Nick Lapis is legislative coordinator with Californians Against Waste, which advocates for elimination of food waste and other organics from landfills as well as other pollution reduction measures.
Nick Lapis is legislative coordinator with Californians Against Waste, which advocates for elimination of food waste and other organics from landfills as well as other pollution reduction measures.

Lapis is the legislative coordinator for Californians Against Waste, an environmental advocacy organization. Those “better things” include grinding up the material into compost. The state is slowly moving in that direction. Residents in the Bay Area have had curbside pickup of their food waste for several years. And a new law went into effect April 1 requiring California businesses such as restaurants that create a certain amount of food waste per week to have it picked up separately.

“Landfill emissions are a really big deal,” Lapis said.

Exactly how big a deal locally will not be known until there is accurate measurement. Any system of comprehensive measurement is in its infancy, but even so, San Diego is behind.

Scripps scientists are part of a project planning team working to put 10 precision analyzers on the ground in the Los Angeles area and coordinate the measurements with aircraft and satellite data.

“I would very much like to see what we are doing in Los Angeles extended to San Diego,” Keeling said. “We are really part of one large urban area.”

Lai would also like to build on his initial drive-around research. He would like to find out just how much methane comes out of the sites he flagged with his analyzer. With the addition of an an infrared gun, he would be able to see the shape of the invisible plumes, and where they are coming from. “That would be awesome,” Lai said. But that work will have to wait. He’s out of funding.

San Diego County’s Methane Problem Visible For First Time