The Oregon Department of Environmental Quality has notified Coffin Butte Landfill’s owners it has identified seven serious violations of state and federal law at the site, most related to dangerous methane leaks.
DEQ found that the landfill’s gas collection system is not large enough to function properly and that it too often runs without an operating flare to prevent landfill gas from escaping uncombusted; that the company does not monitor for methane leaks as required, or fix methane leaks as quickly as required; and that it does not monitor for and fix tears in the surface cover.
In a pre-enforcement notice issued Nov. 6, DEQ warned owner Republic Services it may be cited and fined for the violations, and asked it to voluntarily take actions to correct the problems.
In its notice, DEQ states the company’s failure to control landfill gas emissions already has had significant environmental and public health impacts.
Coffin Butte Landfill accepts waste from nearly two dozen Oregon counties and southwest Washington, including most of Marion’s and and all of Polk County’s.
Phoenix-based Republic Services is the second-largest waste disposal company in the U.S. Company officials declined the Statesman Journal’s interview request.
In an emailed statement, spokeswoman Melissa Quillard said the company will work with DEQ on next steps.
“Much of the notice relates to older matters that have already been addressed” or matters in the process of being addressed, Quillard wrote.
Quillard did not respond to a follow-up question about which violations have been or are in the process of being corrected, or what specific actions the company has taken.
DEQ’s enforcement action came more than three years after a U.S. Environmental Protection Agency inspection found massive methane leaks at the facility, and less than 48 hours after the company won approval for a controversial expansion of the landfill, located just north of Corvallis.
DEQ expects to complete a formal enforcement order, with financial penalties, in early 2026, spokesman Dylan Darling said. That could also include enforceable orders to correct violations.
DEQ enforcing EPA case against Coffin Butte Landfill
Coffin Butte Landfill accepts waste from nearly two dozen Oregon counties and southwest Washington.
It takes most of Marion County’s and all of Polk County’s municipal waste, including some of the waste that previously went to the Reworld Marion incinerator in Brooks. Reworld stopped taking Marion County waste on Dec. 31, 2024.
The U.S. EPA has been investigating the landfill since its 2022 inspection. EPA monitored only a portion of the landfill and documented 61 methane exceedances, 21 of which were more than 20 times over the standard.
During a follow-up inspection in 2024, EPA again monitored only a portion of the landfill and found 41 methane exceedances.
EPA turned the case over to DEQ for enforcement in October 2025, Darling said.
EPA still could pursue its own enforcement action as well, he said.
Republic Services has repeatedly claimed, as far back as October 2023, that EPA had completed its investigation and that the company had already addressed all regulatory concerns.
Meanwhile, Republic Services has been pursuing a controversial expansion of the landfill.
Its first application for a conditional use permit to expand, in 2021, was denied unanimously by the Benton County Planning Commission.
In July 2024, the company came back with another, smaller proposal.
In July 2025, the planning commission again denied the proposal, saying the company had failed to prove the expansion would not seriously interfere with adjacent land uses, alter the character of the area or pose an undue burden on local services.
Republic Services then appealed the planning commission’s decision to the Benton County Commissioners, which decided on Nov. 4 to approve it with more than three dozen conditions.
Darling said the timing of the enforcement action was independent of the local planning decision and was based on when the case was turned over from EPA to DEQ.
Semi-trailers dump trash into Coffin Butte Landfill in Benton County on July 25, 2024.
DEQ identified 7 serious violations at Coffin Butte Landfill
DEQ’s pre-enforcement notice identified seven violations, all Class III, the most serious.
Two of the violations relate to methane monitoring.
DEQ found that, since 2022, Coffin Butte has exempted large areas of the landfill from required methane monitoring by claiming they were too dangerous or inaccessible to walk upon, in violation of state and federal rules.
It also found little evidence that Coffin Butte has performed remonitoring and repairs where methane exceedances were found, as required.
Four of the violations relate to the landfill’s gas collection and control system, which keeps methane and other gases from escaping to the environment.
DEQ found Coffin Butte used incorrect calculations in a 2021 amended design plan for the landfill, resulting in an undersized gas collection and control system. The company’s calculations did not include waste placed in the landfill before 1998, did not use total waste and did not use required model parameters.
DEQ found Coffin Butte failed to amend the design plan after installing a new enclosed flare in 2024.
It also found that Coffin Butte has reported extensive downtime events for its flares, but has not shut down the gas collection system during those events as required.
And it found that Coffin Butte failed to conduct monthly monitoring at each wellhead, as required. Monitoring for gauge pressure, temperature, nitrogen and oxygen help indicate the performance of the well, and results can require corrective action.
One of the violations relates to the integrity of the cover used where waste has been placed but is not at final grade. Maintaining the landfill cover helps minimize landfill gas leaks to the atmosphere.
DEQ found that while the company consistently reported conducting monthly inspections of the cover and finding no issues or holes, a 2024 EPA inspection found many holes and a significant number of trees, some of which were 3-feet tall, growing through the cover.
DEQ also noted, but didn’t identify as a violation, documented incidences of plumes of dust generated when loads are tipped into the landfill. The company’s air pollution permit requires it to prevent particulate matter from becoming airborne.
Coffin Butte Landfill is operated by Republic Services.
Coffin Butte Landfill must hire experts, plan for drone technology
DEQ has asked the company to take the following voluntary corrective actions:
By Jan. 1, 2026:
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Request a change to its air pollution permit that will allow it to use drone technology to monitor methane emissions. After the company makes the request, the process to change the permit, which includes public notice and comment, will take about six months, DEQ’s Darling said. Senate Bill 726, passed by the Oregon Legislature in June 2025, already requires Coffin Butte to use satellite, airflight or drone monitoring by Jan. 1, 2027.
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Submit an operation and maintenance plan for the flare to ensure compliance.
By Feb. 1, 2026:
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Submit a plan to update the landfill gas collection and control system that complies with state and federal requirements.
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Have a third-party conduct an inspection of the entire landfill’s cover integrity, and submit the findings to DEQ.
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Have a third-party conduct a study of fugitive dust control management and options for the landfill, and submit that along with a dust control plan, to DEQ.
Mko Vieux and Becky Merja of Corvallis hold signs against expansion of Coffin Butte Landfill before a hearing at the Benton County Fairgrounds Auditorium on Oct. 23.
Coffin Butte Landfill expansion set for final vote Nov. 17
Benton County Commissioners are scheduled to formally adopt their decision to allow the landfill to expand at a meeting beginning at 9 a.m. Nov. 17 at the county’s Kalapuya Building, at 4500 SW Research Way in Corvallis.
Opponents then will have 21 days to appeal the decision to the Oregon Land Use Board of Appeals, if they choose.
LUBA’s decision can be appealed to the Oregon Court of Appeals.
For more information about the county’s process, go to bentoncountyor.gov/coffin-butte-landfill/
More information about DEQ’s regulation of the landfill is available at oregon.gov/deq/programs/pages/coffin-butte-landfill.aspx
Tracy Loew covers the environment at the Statesman Journal. Send comments, questions and tips: tloew@statesmanjournal.com or 503-399-6779. Follow her on X at @Tracy_Loew
This article originally appeared on Salem Statesman Journal: Oregon finds serious environmental violations at Coffin Butte Landfill
