Phoenix failed to address climate pollutant at city-owned site - The Arizona Republic

Phoenix failed to address climate pollutant at city-owned site

Phoenix touts climate awareness, but hasn't addressed methane levels at city-owned site
Joan Meiners Taylor Seely

Phoenix leaders have done nothing to remediate alarming and explosive levels of methane found seven months ago on city-owned land where a homeless shelter was formerly planned.

That's a problem for the climate, experts say.

Methane, the largest component of natural gas, accounts for nearly one-third of average global temperature increases due to man-made climate change, according to the International Energy Agency. As world leaders seek to address environmental instability tied to atmospheric warming, containing leaks of this potent greenhouse gas has become a priority issue for both the Biden-Harris administration and the United Nations.

Yet while Phoenix officials tout climate awareness, their own documents reveal unchecked methane levels in soil samples at the site rivaling those found at oil drilling wells and landfills where monitoring and capture is required by the Clean Air Act. The contamination may be due to buried waste and debris but is not entirely clear.

Phoenix's Office of Homeless Solutions announced plans to build a shelter in December 2022 on roughly six acres at 22nd Avenue and Lower Buckeye Road. The city reversed course six months later, when it found dangerously high levels of methane and carcinogenic petrochemicals as part of a pre-construction work analysis in June 2023.

Deputy City Manager Alan Stephenson said in November that Phoenix's Office of Environmental Programs would work to remediate the land. But as of mid-February, no one at City Hall could point to any progress.

City officials instead shrugged off the climate impacts and gave limited and vague responses that changed over time when asked about plans to remediate the site. They first said a plan was underway but offered no details and no timeline. Later, they acknowledged the city had not yet hired a contractor for such work. Repeated requests for interviews were denied.

Meanwhile, scientists who reviewed the environmental report for the site say the methane could be relatively easy to address. Until it is mitigated, experts say the emissions will likely continue seeping into Phoenix's air, posing risks to health, safety and the environment.

Their contribution to globally rising temperatures will not be instant or detectable in the immediate surroundings, which include mostly industrial businesses. But the site's excess methane emissions contribute to local ozone pollution.

They also undermine Phoenix's oft-publicized efforts to be part of the climate solution.

Arizona State University life sciences professor and methane expert Hinsby Cadillo-Quiroz called the city's inaction an "ignorance is bliss" approach, at odds with other climate-forward cities.

A climate platform on shaky ground

Addressing climate change and positioning Phoenix as "the most sustainable desert city in the world" has been a centerpiece of Mayor Kate Gallego's platform and goals. Under her leadership, the city created an Office of Heat Response and Mitigation and landed millions in federal funding for shade trees to reduce urban heat.

Gallego's public service career has long centered on environmental issues, and she is a nationally recognized leader on climate action at the city level. She holds leadership positions with the Climate Mayors and C40 Cities initiatives to tackle climate change by coordinating with cities to reduce greenhouse gas emissions.

But the way her office has handled the methane contamination at the city site once slated for a homeless shelter raises questions about how widespread that awareness and commitment to climate issues is among her staff.

In November, The Arizona Republic reported on Phoenix's hushed decision to not proceed with plans to build housing at 22nd Avenue and Lower Buckeye Road after an environmental assessment revealed toxic levels of carcinogens and other harmful chemicals.

'Find a way to make this happen': Phoenix planned homeless shelter on land contaminated for decades

Of particular concern in the results were the levels of methane, which city spokesperson Kristin Couturier told The Republic made the site “unsuitable for construction.” City-funded analyses indicate the city has had some awareness since the 1990s of contamination at the plot.

The 2023 environmental analysis, completed in June, went further by testing the soil for chemicals that would preclude development for human habitation. Out of 18 soil vapor samples collected from randomized locations across the site, 10 registered methane levels well above the lower explosive limit of 5%, the point at which lighting a match in the area could produce a flash of fire.

The most extreme of these samples registered a soil methane concentration of 420,000 ppmv, or parts per million by volume — meaning that 42% of the gas molecules within the soil at that location were found to be methane, or CH4. Five more returned methane gas concentrations between 41% and 8%.

These levels are not only extreme for land under consideration for housing, as the city's decision not to build underscores, they also far exceed the methane content found in soil gas samples taken at a petrochemical site where concentrations would be expected to be high and where monitoring would be required in the U.S. out of concern for climate impacts.

In a 2019 paper published by scientists working on the Dawanqi oilfield in Tarim Basin, China, researchers reported a mean CH4 concentration across 59 samples of 907.1 ppmv, or less than 1% of the total gas content within the soil.

Methane is estimated to have about 28 times the warming potential over a 100-year period as carbon dioxide, the more common greenhouse gas, so it seems reasonable to expect these numbers would have stood out as a problem to an office versed in and focused on climate solutions, said Cadillo-Quiroz.

The Republic shared portions of the environmental assessment with Cadillo-Quiroz, including the map of where soil gas samples were taken across the site and the methane concentrations found there. If the contamination was truly limited to the small area evaluated, he said, it might not add up to much more than would be emitted annually by a typical car. But he believes the results of the environmental assessment obligate the city to do more to evaluate and contain more widespread leaks, which he sees as likely.

"If this, which I believe is likely, repeats in many places and I am not even looking at it, or having a sense to check any of this, then I am not a city that is responsible and actually following up with this," Cadillo-Quiroz said.

City's response contradicts itself

When The Republic followed up about a methane mitigation plan seven months after the report had been filed with the city, officials offered vague and seemingly contradictory answers about whether the city had considered further testing or the need for remediation.

At the same time, the city was applying for a $500 million climate pollution reduction grant from the federal government.

First, Keyera Williams, spokesperson for Phoenix's Office of Environmental Programs, said in January that the city was "continuing to develop a remediation plan" but noted a use for the site hadn't been determined. She declined to answer questions about mitigation methods under consideration and denied The Republic's request for an interview.

Then a spokesperson for the mayor also declined an interview, saying the mayor's office was not involved, and referred reporters back to the Office of Environmental Programs.

When questioned more specifically about the need for remediation due to climate concerns rather than just prior to development, Williams responded to The Republic two weeks later, saying the site's methane was "contained in the soil" and "not being released into the atmosphere or exacerbating climate change."

But Cadillo-Quiroz said that would be impossible for the city to claim without having done above-ground air monitoring at the site, which he said could be accomplished quickly and easily by walking around the area with a portable detector. When asked whether the city had done such tests, Williams pointed back to the June report, which only analyzed below-ground soil gas levels and did not reveal how much methane is rising to the surface.

Finally, The Republic contacted James Marshall, the environmental programs coordinator for the city's Streets Transportation Department, to whom the environmental assessment was addressed in June, to ask why he hadn't followed up on the report's recommendations to mitigate methane emissions. After that, Williams sent another response Thursday suggesting a sudden pivot in their approach.

"The city recognizes the methane may present a possible hazard should the soil be disturbed so therefore, the city will not wait for a land use to be determined, but is currently working with a contractor now to address the methane and other soil gases," Williams wrote Thursday morning.

When The Republic requested more information on when the city began working with the contractor, Williams revised her statement Thursday afternoon to say the city was "in negotiations with contractors."

How bad are these methane levels, really?

It's true that methane concentrations in soil samples do not easily translate into amounts of methane gas released into the atmosphere. Those calculations depend on soil type, ambient temperature, moisture levels and other variables not fully known for the Phoenix site, said Cadillo-Quiroz.

But in a research paper published in 2021, the team of scientists working at the Dawanqi oilfield in China tested methane release from the soil into the atmosphere during different seasons and concluded that more "microseepage" takes place at higher air temperatures. This occurs in a passive way even without soil disturbance, Cadillo-Quiroz clarified.

Extreme temperatures in Phoenix mean that heat-accelerated emissions from the highly contaminated soil at the city site may exceed those subjected to federal monitoring requirements at petrochemical sites. In December, the U.S. Environmental Protection Agency announced a final rule requiring more comprehensive methane monitoring by oil and gas companies at well sites, as part of the push to control global methane leaks.

The EPA is also ramping up methane monitoring and containment efforts at agricultural sites and landfills, the two other primary sources outside of the petrochemical industry. Cadillo-Quiroz said the methane levels found at the Phoenix site are concerning and resemble those measured at landfills, where the decomposition of organic waste produces methane concentrations requiring intervention to manage both the climate effects and risks of explosions.

According to Cadillo-Quiroz, "500,000 to 400,000 ppmv is the common max of landfills internal methane concentrations. Landfills may be required by law or EPA regulation to keep emissions below certain levels."

In 2021, the EPA estimated landfills account for 14% of all U.S. methane emissions, equivalent to the annual emissions from 23 million gasoline-powered passenger vehicles. An August 2023 report from the Congressional Research Service bumped that up to 17%. Project Drawdown, a nonpartisan research organization, has also identified methane emissions from landfills as an important climate risk.

As a result, many of these waste facilities are increasingly taking action to contain the harmful methane emissions created during the decomposition of organic waste, and even turn them into natural gas for use on site as fuel.

The Phoenix-based company Republic Services launched plans to capture methane at 39 of its landfills across the country in 2022. The strategy involves building a barrier beneath the landfill to prevent leaks and then capping the entire site and sucking methane gas rising from the surface into pipes.

More: Rags to riches? How trash at landfills can be recycled into energy as flammable gas

In the environmental report addressed to city employee James Marshall in June, the authors highlighted the similarities between their soil gas sample results and the harmful emissions at landfills, and included the following recommendation: "An area-wide methane (or landfill gas) mitigation system may also be beneficial, since there is evidence that the site was used for disposal of construction debris."

Marshall did not directly respond to inquiries about the city's lack of response to the recommendation.

Cadillo-Quiroz said the city has numerous options to address the methane coming off its former homeless shelter site. It could follow the model set by landfill industry operators like Republic Services and cap the site, vacuum off the methane and maybe even use it to fuel other small city operations, sparing those additional carbon emissions.

Another option would be to cover the site with a layer of soil full of methanotrophic bacteria naturally present in ecosystems like forests and wetlands that would serve to oxidize the methane into less harmful byproducts as it bubbles up through the added soil.

Vegetation planted on that layer could further support the microbial communities and facilitate the breakdown of methane before it reaches the atmosphere, Cadillo-Quiroz said. One caveat of this strategy is that moisture is required and the process has not been thoroughly studied in dry environments. But he sees it as a better bet for the climate than the one the city has taken so far, of doing nothing.

"Should the city take action now that they know they have one of these places releasing (high levels of methane)? The answer is, it might not take that much to cover and slow down (the methane release)," Cadillo-Quiroz said. "There are many other cities that have taken action. If we are trying to be at the forefront of sustainability and be a climate-conscious type of city, then ideally that should be a concept to put forward."

'We don't have the luxury of taking an ignorance is bliss approach'

Alongside the question of whether Phoenix will voluntarily address high levels of methane at the site it once considered for a homeless shelter in accordance with its climate goals, is whether it may someday be required to.

When Cadillo-Quiroz spoke with The Republic in January, he had just returned from a meeting of experts in California focused on setting a nationwide agenda for atmospheric methane removal, which was identified as a key climate mitigation goal in the latest National Climate Assessment published last November.

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He said there is currently no regulation of methane emissions on private land. But on public land? Based on his involvement in the field, he said he thinks that might be in the pipeline of policies the White House's Methane Task Force is working on. When Phoenix purchased the plot on Lower Buckeye, it became a public site, susceptible to these future regulations.

But for now, what next steps the city will take remain more about alignment with stated local climate policies and goals. With the issue raised by The Republic, the city is now claiming to be in negotiations with contractors to address the same methane emissions they two weeks prior dismissed as "not exacerbating climate change." As negotiations and mitigation plans unfold, only time will tell whether the city's actions match its policies. And methane experts say there is no time to waste.

"If there is a major hotspot like this with values that high, it wouldn't take a dramatic effort to do some type of basic surveillance approach. And then once you have that, you have magnitude (of the problem)," Cadillo-Quiroz said. "But without that information, the city is taking an 'ignorance is bliss' approach. And we don't have the luxury of taking an 'ignorance is bliss' approach."

Joan Meiners is the climate news and storytelling reporter at The Arizona Republic and azcentral.com. Before becoming a journalist, she completed a doctorate in ecology. Follow Joan on Twitter at @beecycles or email her at joan.meiners@arizonarepublic.com. Read more of her coverage at environment.azcentral.com.

Reporter Taylor Seely covers Phoenix for The Arizona Republic / azcentral.com. Reach her at tseely@arizonarepublic.com or by phone at 480-476-6116.