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7 Things You Need to Know About the Porter Ranch Gas Leak

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The Aliso Canyon wellhead that blew out in October | Photo: Earthworks/Flickr/Creative Commons License

Watch SoCal Connected's special report on Porter Ranch Wednesday, March 2 at 8:00 p.m.

As of February 18, the massive natural gas leak at the Aliso Canyon oil and gas field in the Santa Susana Mountains is declared plugged. Residents of Porter Ranch, the community hardest hit by the catastrophic fossil fuel spill, are preparing to return to their homes, and the state's lawmakers are now deciding whether to make SoCalGas, the owner of the leaking well, close down its Aliso Canyon gas storage operations entirely.

The announcement that the leak had been plugged didn't come a moment too soon. The Aliso Canyon leak has been ranked as an environmental disaster rivaling the 2010 Deepwater Canyon oil spill in the Gulf of Mexico in terms of its eventual damage to the environment. That's mainly due to the damage the spilled natural gas will cause to the planet's climate: methane, the main constituent of natural gas, is a potent greenhouse gas, about 21 times more damaging to the climate than CO2 (carbon dioxide) for 100 years after it's released into the atmosphere. The spill at Aliso Canyon -- the largest single release of methane in U.S. history -- was a significant setback to California's attempts to address the threat of climate change.

So we're rightly relieved that the leak seems to be over. But before you exhale all the way, there are a few things to keep in mind about the larger context in which the Aliso Canyon disaster happened.

The only thing unusual about the Aliso Canyon gas leak was its size. 

Aliso Canyon may have been the largest single atmospheric release of methane in U.S. history, but despite its devastating scale, methane releases continue at a rate that might well make Aliso Canyon seem like a blip. Preliminary estimates of the total amount of gas leaked at Aliso Canyon run at least 80,000 total metric tons over the 118-day course of the leak. That's about 29 metric tons of methane spilled per hour, on average. (Some estimates run as high as 100,000 metric tons.)

Sounds like a lot, and it is. But consider this: according to the U.S. Environmental Protection Agency, the American oil and gas industry spills about 7.3 million metric tons of methane a year into the atmosphere. That's an average of more than 833 metric tons of methane per hour, almost 30 times the conservatively estimated hourly rate of the Aliso Canyon leak.

Put another way: The typical background rate of ongoing methane emissions just from the oil and gas industry equals about 30 Aliso Canyons.

Some of that leaks from aging pipelines and storage facilities, oil refineries and other infrastructure. Some of it leaks from the gas fields from which gas and oil is extracted in the first place. The EPA once estimated that 2 percent of the methane produced at many gas fields escaped into the atmosphere. A recent study of gas fields in Colorado's Denver-Julesburg basin put the actual figure twice as high, and so did a December 2015 study of gas fields in north Texas. 

And that's just direct emissions by the fossil fuel industry. Methane also leaks from retail gas companies' aging infrastructure -- as residents of San Bruno tragically learned when a poorly maintained PG&E pipeline exploded in 2010. As Christie Aschwanden reported this month at, major cities often have hundreds or thousands of natural gas leaks going unreported and unrepaired. More gas is spilled by agriculture, deliberate burning of biomass, and by garbage decomposing in landfills. All in all, the EPA estimates that the U.S. dumps 25 million metric tons of methane into the atmosphere -- 312 Aliso Canyons -- each year. And other sources suggest it's closer to 40 million tons per year.

Most of the gas leaked from Aliso Canyon came from southwestern oil and gas fields where hydraulic fracturing, and methane leakage, is commonplace.

Despite California's role as a pioneer in fossil fuel extraction, with oil and gas wells dating to the early 20th Century, the state actually relies on supplies from other parts of the country for the large majority of its natural gas use. SoCalGas, which operates the Aliso Canyon well that caused the leak, imports the majority of its natural gas via the El Paso Natural Gas and Transwestern pipelines from gas fields in the American Southwest.

That bright red dot is the San Juan Basin's methane leak. Map: NASA

And that mainly means SoCalGas filled the Aliso Canyon storage reservoir with gas from fields in the San Juan basin in the Four Corners area, which has been the nation's largest single source of methane emissions for years. So much methane leaks into the atmosphere from the San Juan Basin's 40,000-plus wells that one basin contributes 10 percent of the natural gas industry's methane emissions.

The San Juan Basin was a major emitter of methane even before the advent of the now-widespread practice of hydraulic fracturing, a.k.a. fracking. But over the last few years, as the San Juan's coalbed methane began to be a little harder to extract, oil and gas companies turned to fracking the local Mancos Shale to boost production. Fracking hit the San Juan Basin in earnest in 2013.

As documented by Julie Dermansky at DeSmog Blog, the result has been a rapid expansion of fossil fuel drilling on federal and tribal lands, with startling effects on both the local environment and local cultural resources -- shockingly including the world-class cultural site at Chaco Canyon.

Another major source of SoCalGas's supply is Texas' Permian Basin, North America's largest oil producer,  where fracking has allowed the drilling of around 10,000 new wells since 2011.

And fracking is increasingly regarded as a potential cause of increased methane leaks from southwestern oil and gas fields.

None of this is to say that SoCalGas's Aliso Canyon facility is directly responsible for fracking in those and other southwestern gas fields. But the link does highlight the close tie between the purpose of Aliso Canyon's storage reservoir -- to buy up gas when it's cheap for later sale to ratepayers -- and part of the reason natural gas is cheap in the first place.

And speaking of fracking;

Wells in the Aliso Canyon oil and gas field have been fracked. 

According to a report put out in January 2015, hydraulic fracturing of storage wells is commonplace in Aliso Canyon. Storage wells are fracked in order to increase output, in much the same way that fracking stimulates output at wells that produce oil and gas in the first place. The well responsible for the blowout hadn't been fracked, but one nearby well had been fracked before the accident. How close is "nearby"? Less than half a mile, according to state records, though Jason Marshall, chief deputy director of the California Department of Conservation said in January that the closest fracked well was more than 1,500 feet away. So triangulate from there.

That's not to say the fracking was necessarily linked to the accident. (In fact, Marshall dismisses the possibility.) But given what fracking entails -- the injection of high-pressure fluids into deep wells to fracture underground rock formations -- the notion that fracking one well might cause breaches in a well nearby certainly seems worth checking out.

And in fact, industry best practices recommend just that: when a well is fracked that's close to storage wells, the American Petroleum Institute's guidelines recommend that thorough checks be performed to ensure the integrity of those storage wells. Oddly enough, when the state proposed new emergency regulations to prevent more Aliso Canyons, those regs didn't include checking the integrity of storage wells after fracking projects.

What's more, SB 4, the 2013 law that requires public discosure of fracking, specifically exempts storage wells from public notification requirements.

A defective gas transmission pipeline caused this devastation in San Bruno when it exploded in 2010 | Photo: Thomas Hawk/Flickr/Creative Commons License

Some of the infrastructure at Aliso Canyon is very old. So's much of the rest of the county's natural gas infrastructure.

Aliso Canyon started its petrochemical era in the 1950s, when the region was drilled with hundreds of oil wells. When the oil reserves in the area gave out, starting in the 1970s, 115 of the wells were converted to  use the emptied oil deposits to store natural gas.

Though SoCalGas did upgrade and repair many of those wells as time passed, 39 of them are reportedly more than 50 years old. SS-25, the well that blew out in October, was first put into operation as an oil well 62 years ago. Though it was upgraded in the 1970s, the pipes that connect the wellhead to the storage reservoir were not. If those pipes were people, they would be eligible for Social Security this year.

Every day that passes means the remaining infrastructure in Aliso Canyon is a day older. Especially in an area as seismically active as the Santa Susana Mountains, aging equipment is vulnerable to breaches. Most won't be as dramatic as the blowout of SS-25; most will likely go unnoticed except when someone measures how much gas is left in storage. 

And there's this: Aliso Canyon is just one of more than 400 underground natural gas storage facilities in the U.S. Sure, it's one of the biggest: all told, the entire field can hold almost a cubic mile of gas. But other fields with aging components can leak just as badly. 

And when you consider that many of the large pipelines that move natural gas across the continent to and from those storage facilities were built in the 1960s or earlier, the potential for additional methane leaks becomes obvious. The United States boasts almost 320,000 miles of natural gas transmission pipelines -- that's not including the distibution pipelines that bring the gas to our homes, workplaces, and schools. Of that nearly 320,000 miles of transmission pipeline, just under 141,000 miles was built between 1950 and 1970. More than 30,000 miles of pipeline is even older than that.

Large leaks in transmission pipelines are theoretically easier to plug than the leak at Aliso Canyon, which was in a hard-to-pinpoint spot deep underground. But small leaks may go unnoticed for months or years.

Or they might get noticed in a huge hurry, as was the case with PG&E's 30-inch transmission pipeline that leaked due to defective welds beneath the streets of San Bruno, causing the deadly explosion of September 2010.

Part of the reason for the increase in natural gas use is our climate change strategy

America's electrical power grids were once mostly run on juice from coal-fired power plants. Coal produces a little more than two pounds of carbon dioxide for every kilowatt hour of power produced. Natural gas power plants produce an average of about 1.2 pounds of COper kilowatt-hour.

That's a big difference: in theory, you could cut power plant emissions by almost half by replacing coal plants with gas-burning plants.

Of course, as we see above, the CO2  that's produced when you burn natural gas is only part of the fuel's climate impact. The methane that escapes into the atmosphere from natural gas production, transmission and end use is estimated by some groups to total about nine percent of America's total methane production. If those estimates turn out to be accurate, that would neatly erase natural gas's climate advantage over coal.

There's another difference between coal and natural gas that has contributed to the latter fuel's rise in use for power generation. Coal-fired plants can take as long as four to six hours to start generating power from a cold start. They're thus built with the assumption that they'll be used as close to 24/7 as possible as so-called "base load" plants to avoid those long startups.

Natural gas-fired power plants don't have that drawback: depending on their design, they can take as little as ten minutes to generate power after a cold start. That allows utilities to use natural gas as a source of so-called "dispatchable" power: they can be pressed into service almost immediately when grid operators notice a surge in power demand.

The same goes for when those grid operators anticipate a drop in supply, and that becomes important as we move to a greater reliance on solar and wind power. The sun goes down reliably every day, and the wind stops whenever it feels like it, and when that happens utilities can fire up their natural gas-fired power plants to make up the difference.

In California, we use about 25 percent of our natural gas to generate power. (The rest goes to heat homes and businesses, and an increasing amount is used to power alternative fueled vehicles.) As cities like Los Angeles plan to wean themselves from coal power, utilities increasingly turn to natural gas as Plan B. And not just coal: a wave of new gas-fired power plant proposals arose as the ailing San Onofre Nuclear Generating Station went out of service a couple years ago.

The link between natural gas and climate, not only as a coal replacement but also as a supplement for renewables, did not escape hype. Billed as a "bridge fuel," with the promised land of clean power presumbly at the other end of the bridge, natural gas enjoyed a brief moment of popularity among green energy groups -- though few went as far as  the Sierra Club, which famously took $25 million in donations from the natural gas industry to fund its Beyond Coal campaign. (Pressure from the Club's grassroots anti-fracking activists helped end such arrangements in 2010.)

Environmental groups have rethought their relationship to natural gas, but government has not. Natural gas is a linchpin of the Obama administration's 2015 Clean Power Plan, which sets state-by-state emissions reductions targets for electrical power plants. As the targets address smokestack emissions but not the emissions of the infrastructure that brings fuel to those plants, that means the Clean Power Plan will involve shipping natural gas through leaky transmission pipelines built before President Obama was born. 

The jury's still out on the public health impacts of the Aliso Canyon disaster. 

One bit of good news for the residents of Porter Ranch and the rest of Southern California: methane, the main constituent of natural gas, is essentially non-toxic. The other constituents of natural gas are more problematic. Right now, there's a dispute -- and a wrongful death lawsuit -- over whether the accident contributed to one resident's death; the victim, 79-year-old lung cancer patient Zelda Rothman, experienced respiratory distress in her home three miles from the leak, and died in January after a period of sharply declining health.

That case will be decided in the courts. For around 30,000 other residents of Porter Ranch, the path to answers about the accident's impact on their health isn't so clear.

Much of the press attention on potential health risks from the accident centered on benzene, a common contaminant in natural gas. That's with good reason: benzene is a known human carcinogen. Exposure to the chemical has been conclusively linked to a greater risk of leukemia, as well as other disorders of the blood-producing cells of the bone marrow such as anemia.

SoCalGas took some heat in the national press for failing to publicize tests that showed elevated levels of benzene in and near Porter Ranch.

Benzene spilled into the Porter Ranch area from Aliso Canyon definitely merits concern. With a half-life in the lower atmosphere of about 10 days, it will be summer before the benzene released from Aliso Canyon is mostly broken down by sunlight and oxygen. Reputable agencies differ over how much benzene exposure is safe. The Occupational Safety and Health Administration says it's unsafe for workers to be exposed to benzene in the air at concentrations of more than one part per million. That's about 200 times higher than the highest concentration recorded (and then made public) at Porter Ranch. But on the other hand, the World Health Organization holds that there's no safe level of benzene exposure.

According to some Porter Ranch area air quality test results, there was as much toluene in the local airshed as there was benzene during the spill. Toluene, which is another common contaminant in natural gas, is significantly less dangerous than benzene. But it’s still toxic, and inhaling large amounts can cause nervous system damage.

Another suite of chemicals found in natural gas are added deliberately by the energy industry. Methane is odorless, which is a really dangerous quality for a highly flammable, leak-prone gas to have. So gas companies add sulfur compounds called mercaptans, which stink, to make it obvious when natural gas leaks into the atmosphere. That's what you smell when your pilot light goes out: the so-called "odorants" added by the gas company.  

The most commonly used odorant, methyl mercaptan (also called methanethiol) is highly toxic at high concentrations, though such concentrations far exceed the amount that would create an unbearable odor. Gas from the Aliso Canyon storage facility contained methyl mercaptan and a number of other sulfur compounds, which were detected in local air at concentrations totaling as high as 150 parts per billion in November. We're likely to hear discussion in the weeks and months to come of the impact of those odorants on respiratory health: the chemicals are potential triggers for asthma attacks and bronchitis during short-term periods of exposure at levels like those at Porter Ranch, and can cause nausea and vomiting as well.

The short-term effects of mercaptans and similar compounds are well known. Researchers are investigating the long-term health effects of exposure to those odorants. They're also going to be examining the effects of chronic emotional stress the accident spurred in Porter Ranch residents.

Two worries heralded in some social media that Porter Ranch residents probably don't have to worry about: uranium 238 -- with one site claiming "lethal levels" of the radioactive element were coming out of the well --  and formaldehyde. The first claim probably originated from misinterpretation of sensible concerns over potential radon gas pollution from the well, as radon is a naturally occuring breakdown product of uranium. Porter Ranch residents would likely be dealing with any potential radon threat by thoroughly ventilating their houses, which one would expect they'll be doing anyway once the last traces of odorant are gone. But if "lethal levels" of U-238 were coming out of that wellhead, we'd be able to see it from the 118 Freeway: with a half-life of more than four billion years, uranium 238 is almost non-radioactive. (It's the much more radioactive U-235 that goes into weapons of mass destruction and unpopular power plants and such.)

As for the formaldehyde threat, there's been a consistent thread in some online circles claiming that the compound -- sometimes referred to as "embalming fluid" -- is "gushing" from the Aliso Canyon well, causing dire health problems in locals. There's a germ of truth behind the claims. Formaldehyde, which is indeed highly toxic and a known carcinogen, is also (indeed) formed when methane breaks down in the presence of sunlight and water. To get technical for a moment, atmospheric methane reacts with hydroxyl ions -- essentially water molecules missing one of their two hydrogen atoms -- to form formaldehyde. 

Where the notion that formaldehyde poses a serious and media-suppressed threat to Porter Ranch residents fails is that those same hydroxyl molecules that react with methane react with formaldehyde even more readily, creating carbon dioxide and water.

Think of it this way: if the methane was really breaking down as quickly as claimed and forming formaldehyde, that would be really bad for Porter Ranch residents, not to mention the workers at Aliso Canyon. But it would mean there was nearly no threat to the planet's climate from the accident, or indeed from any methane leak: formaldehyde isn't a greenhouse gas. In truth, the typical half-life of methane in the lower atmosphere is somewhere in the neighborhood of 10 years: by the time the methane leaked at Porter Ranch breaks down to appreciable amounts of formaldehyde, it'll be scattered by winds around the globe.

The Haynes Steam Plant, a gas-fired power plant in Long Beach | Photo: Jon Sullivan/Flickr/Creative Commons License

The ordeal Porter Ranch residents have been through is everyday life for thousands of Californians.
The suffering of Porter Ranch residents is real, running the gamut from extreme inconvenience and financial loss to tragedy. It's by no means minimizing that suffering to point out that the relatively affluent demographic status of the community played a role in the degree of official attention paid to the public health effects of the Aliso Canyon spill. Throughout California, chronic exposure to toxics is far more commonplace in less-affluent neighborhoods and communities of color.

Porter Ranch residents themselves have mentioned this, pointing to lead contamination in East Los Angeles by the Exide battery recycling plant as an example of government negligience that fuels their mistrust of official pronouncements of their safety. Even when just looking at the natural gas industry, Porter Ranch is a bit of an anomaly. Across the state, many natural gas installations are sited in less-affluent communities, from new power plants in places like Oxnard and Desert Hot Springs to the notorious natural gas compressor plant in Hinkley whose PCB contamination was dramatized in the film Erin Brockovich.

You can explore which communities in California are hardest-hit by pollution from natural gas and other industries using the EPA's Environmental Justice mapping tool. It's a good source of perspective on the issue. Hopefully, now that the Aliso Canyon leak has been plugged, life can start getting back to something like normal for Porter Ranch residents. But though the mercaptans may dissipate from Porter Ranch, the larger issue of disproportionate exposure to toxics by poor people and communities of color will remain.

For the record: this piece has been edited to clarify the differing estimates of the amount of gas leaked from Aliso Canyon.

Watch SoCal Connected's special report on Porter Ranch Wednesday, March 2 at 8:00 p.m.

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