Beyond the Federal Floor

Oregon and Michigan Regulators Approved Elevated Wellhead Temperatures Even Though the Landfill Could Be Much Hotter Inside

At Wasco County Landfill in Oregon, records do not show DEQ requiring direct measurements of conditions inside the waste mass before approving temperatures as high as 170°F. Multiple wells exceeded the federal 145°F threshold, including wells reaching 179.4°F.  DEQ's approval relied on factors such as low carbon monoxide, active methane production, low oxygen concentrations, and the absence of visible signs like smoke, burning odors, settlement, or melted infrastructure. The records reviewed do not show that DEQ required or received borings on temperatures within the landfill, or a root cause analysis, before approving the high temperatures.  Separate annual reporting records show that the landfill later documented corrective actions, enhanced monitoring, down-well temperature profiling, and a tentative explanation of the higher temperatures, attributing the heat primarily to “older waste”, with magnesium chloride identified as a possible contributing factor. The records reviewed do not show those analyses being submitted to DEQ as part of the HOV approval request.

At WM’s Woodland Meadows Landfill in Wayne County, Michigan, the landfill had more than forty gas wells operating under approved temperature variances in 2015. By 2020, that number had grown to more than fifty. Yet the approvals were granted repeatedly based on wellhead gas chemistry — the same measurements coming out of the same wells — without requiring what the situation most fundamentally called for: direct measurement of what was happening inside the waste mass. At no point in the records does the question appear to have been formally asked: if the wellhead is reading 160°F, how hot is the waste ten feet below? Forty feet? Michigan's environmental regulator, the Department of Environment, Great Lakes, and Energy (EGLE), required corrective-action analyses, gas collection expansion, and surface methane monitoring, which represents more oversight than some states provide. But the records do not show requirements for downhole temperature profiling before dozens of wells were approved to operate above normal regulatory limits year after year.

Michigan’s Arbor Hills Landfill: A Landfill with Decades of Red Flags and Elevated Temperatures Misses an Elevated Temperature Event

Arbor Hills Landfill, now owned by GLF Environmental and straddling Wayne and Washtenaw Counties in Michigan, has had numerous allegations and legal actions over several decades, involving allowing methane to reach explosive levels, odors that harm quality of life, failure to control leachate and more. In April 2019, state inspectors found what they called an "Elevated Temperature Landfill event" that had likely been building for over a year and was already damaging the site's gas collection system. Instead of requiring the company to fix the underlying heat, regulators started doing something else: approving waivers that let individual wells run hotter than the standard regulatory limit.

In 2020, as odor violations continued to mount, the state sued the landfill operator. The resulting 2022 court settlement covered a laundry list of problems: odors, a leachate system overflowing its limits, methane again crossing the explosive threshold at the property line, and concerning well temperatures. Ultimately, it resulted in a $355,000 fine plus nearly $2 million in required community projects. But the settlement did not end the practice of operating wells above the regulatory temperature limit. EGLE continued approving and extending Higher Operating Value waivers after the settlement. Months later, a state inspector's own site photo described cracked ground near one of the wells as caused by "a subsurface chemical reaction that is charring the waste.”

The problems have remained concentrated on the north side of the landfill, the same area where the company has proposed building a new facility. Between 2022 and 2024, Arbor Hills installed 20 replacement gas wells, replacing 21 abandoned wells in the Well of Interest area and the surrounding 250-foot zone. At the same time, GFL began planning its next landfill expansion on the north side of the facility, submitting a conceptual expansion plan to EGLE in November 2024. One of those replacement wells showed increasingly concerning conditions in early 2025: methane fell from about 30 percent in mid-January to single digits by February and March, carbon monoxide reached 150 ppm, and the wellhead temperature climbed to 177°F in March. Even as those warning signs emerged, EGLE approved the company's request to allow the well to operate at temperatures up to 180°F through May 2026 after reviewing the company's submission and requesting carbon monoxide sampling data. The approval does not document a root cause analysis explaining why the well had deteriorated before authorizing continued operation at the higher temperature, or the broader suite of investigations and supporting documentation that Ohio EPA guidance now recommends.

Finding #3: Lack of Transparency and Fragmented Authority Leaves Residents in the Dark

Additionally, we found that authority can be divided among numerous federal, state, regional, and local agencies, contributing to uncertainty around who’s responsible. At Chiquita Canyon, at least nine agencies — including the U.S. EPA, CalRecycle, the State Water Resources Control Board, and the South Coast Air Quality Management District — making it difficult to identify who leads as conditions worsen.

Regulators cannot effectively oversee elevated-temperature landfills if they do not maintain a complete inventory of which wells or facilities have received exemptions, when those exemptions were granted, how long they remain in effect, or what monitoring requirements apply. Colorado's system demonstrates why formal tracking of HOV approvals is essential. When we requested records identifying which landfills had received HOV approvals, the Colorado Department of Public Health and Environment responded that it does not track such approvals and suggested searching for landfill gas collection system applications and approval letters individually. That proved extremely difficult. A regulatory program that allows exceptions to a key safety and compliance threshold should, at minimum, maintain a searchable record of those exceptions.

Louisiana illustrates the same gap. LDEQ said in an email that it doesn't capture HOV requests in its data systems and pointed us to its public document databases, but those databases appear incomplete. A search for River Birch, the state's second-largest methane emitter, returned over 100 documents requesting elevated-temperature approvals, but corresponding approval letters or final determinations were often absent. A search for "higher operating temperature" turned up only a handful of documents despite evidence more requests had been filed over time. The public can see what operators requested, but not how regulators responded, whether requests were approved, denied, modified, or conditioned on further monitoring. Mississippi was unable to provide electronic records identifying which landfills had received higher temperature approvals. They informed us that decades of paper files would need to be manually searched on-site, effectively putting the information out of public reach.

Obtaining the documents necessary to conduct this analysis required months of time-consuming and sometimes costly records requests, something most people simply don’t have access to. In most states, none of the information we received was easily available. What’s even more concerning about this is how much we don’t know even after receiving information, as it was often incomplete. The Florida Department of Environmental Protection was very responsive to our request, providing a spreadsheet of dozens of HOV or oxygen requests. But the spreadsheet had numerous blank fields and no accompanying documentation. When we asked for the underlying records, we were referred to a central public database that proved time intensive to search with incomplete records.

When the System Fails

Republic Services’ Countywide Landfill 

Countywide Recycling and Disposal Facility in East Sparta, Ohio, which is owned by Republic Services, provides one of the clearest examples of how an early-2000s elevated-temperature reaction can become a decades-long problem. Roughly 600,000 tons of aluminum-process waste were disposed of there between 1993 and 2006. By 2006. By 2006, the landfill documented rapidly increasing temperatures in multiple gas wells, forceful leachate outbreaks, accelerated settlement, odors, declining methane concentrations, increasing hydrogen concentrations, and carbon monoxide generation. Temperatures were later reported as high as 280°F.

The Ohio EPA declared the facility an air pollution nuisance in September 2006 and, in 2007, found that Countrywide had violated the state’s rule prohibiting landfill fires.

The reaction also physically altered the landfill. A Countywide investigation concluded that a portion of the south waste slope had moved as much as twenty feet outside the permitted waste-disposal limits. Regulators required Countywide to stop filling portions of the landfill, expand dewatering, install deeper remediation wells, cap and contain the reaction area, redirect reaction gases and construct a physical Isolation Break. Completed in 2009, that barrier separated the 88-acre remediation unit from the landfill’s remaining 170-acre operating unit and was intended to prevent the reaction from spreading.

Nearly two decades later, the remediation continues. The landfill’s October 2024 submission states that Countywide is still generating roughly times the leachate of a typical landfill, and no one knows how long the reaction will persist. Critically, the remediation plan doesn’t rely on wellhead temperatures alone. It also tracks gas chemistry, methane-to-carbon-dioxide ratios, settlement, and leachate volume together, with defined triggers for further investigation.

Waste Connections’ Chiquita Canyon Landfill and Avenal Landfill

Since 2022, Chiquita Canyon Landfill has been in a crisis. The reaction zone has grown to roughly 90 acres, more than triple the operator’s original estimate. Inside Climate News found the landfill emitted nearly 30,000 pounds of carcinogens between 2000 and 2022, including about 6,000 pounds of benzene. In a rare action, the U.S. EPA invoked “imminent and substantial endangerment,” citing the risk of hazardous leachate releases, and multiple state agencies have issued violations for gas control and hazardous waste failures. 

The surrounding community is predominantly Latino, and the landfill sits near multiple K-12 schools and faces ozone levels worse than nearly 97 percent of the country. Over 29,000 residents have filed odor complaints, reporting nosebleeds, breathing difficulty, brain fog, and cancer diagnoses. 

The same question applies to both Chiquita Canyon and Countryside: if this is the investigation regulators know is necessary once a crisis is recognized, why isn’t anywhere near that level of scrutiny required when landfills first show warning signs? 

At the Avenal Landfill in central California, Waste Connections' 2024 response to abnormal landfill temperatures focused on managing the symptoms rather than investigating the problem. The Avenal Regional Landfill sits just 500 feet from the nearest residence, with the entire town of 14,000 people living within 1.5 miles of the site. As temperatures increased and landfill gas chemistry deteriorated, the company repeatedly adjusted the gas collection system, increased vacuum, installed well skirts, and sought approval to operate at higher temperatures. But the record does not show that it determined the root cause - why multiple wells were heating up. Waste Connections did not collect down-well temperatures because its internal trigger had not been reached, did not explain the large "balance gas" fraction that appeared in the gas analyses, and did not demonstrate that it had identified the underlying cause of the elevated temperatures. Meanwhile, temperatures continued to climb, methane concentrations declined, and carbon monoxide increased dramatically in several wells—all warning signs that EPA's own guidance associates with an elevated-temperature landfill reaction.

In a move different from most reported in the records examined, U.S. EPA Region 9 was not persuaded (although it is notable the EPA did not respond to the landfill’s July 2024 request until April 24, 2025 — a delay of almost a year). Instead of simply approving higher operating temperatures, the EPA concluded that several wells showed evidence of an anaerobic subsurface exothermic reaction. The agency denied HOV requests for four wells and required Waste Connections to do what it had not yet done: investigate the problem. It directed the landfill to collect down-well temperature data, improve cover integrity, evaluate whether additional extraction wells were needed, replace wells that could not safely withstand the temperatures being encountered, and submit revised root cause and corrective action analyses. The EPA also rejected the company's request for more time, emphasizing that an HOV request is not a substitute for corrective action. 

Despite those actions, the problems at Avenal Landfill have continued. Public records show wellhead temperatures exceeding 160°F, methane concentrations falling into the single digits in some wells, and carbon monoxide concentrations reaching levels that California guidance identifies as strong evidence of a subsurface fire. Residents living just hundreds of feet from the landfill continue to report odors and have called for an emergency, multi-agency response, air and leachate testing, down-well temperature monitoring, and regular public updates. Through a rule loophole, the Avenal Landfill continues to operate on an air permit that expired in 2021. The San jJaquin Valley Air District refuses to public notice the permit as directed, and both the California Air Resources Board and U.S EPA. refuse to pursue enforcement action.

The Avenal case demonstrates the consequences of failing to investigate elevated temperatures early: by the time regulators recognized the seriousness of the problem, the community was already living with the impacts of what appears to be an ongoing subsurface reaction.