Local residents are questioning why the Corson maize mill noise rules were relaxed by council staff after years of complaints, and some councillors are questioning why they didn’t know the decision had been made.
The Corson mill is a big thing in Australian grain processing, with 10% of Australia’s maize going through the system, and the mill has spent two years and $300,000 trying to mitigate noise at the site using the latest technology.
The question is not whether one of the area’s leading employers, who brings in an estimated $35 million annually to the local economy, is being a good neighbour, or whether local residents have a right to expect better amenity and a quiet life. The question is whether SDRC staff should have brought the question to local councillors for review.
“We’ve been living here for 37 years or so,” one resident said. “When we moved, the site was vacant. The buildings were there, but there was no business.”
That changed after the late Wayne Goss officially re-opened the Churchill Drive facility in 1991.
The background
The noise problem didn’t impact locals until 2018 when the company, now under the ownership of Corson Grain Australia Pty Ltd, added the additional silos. At first it was fine, but then the mill “became more intense”, according to one resident.
The continuous drone prompted the resident to investigate how the operation was being regulated. But it was only recently, after reviewing council records and environmental approvals, that residents began questioning why changes to the mill's operating conditions never came before elected councillors, particularly since there was an existing Environmental Enforcement Order in place.
The trajectory began in 2018, when council fixed a maximum noise level to no more than five decibels above the existing background noise at nearby residences and 10 decibels above background at commercial premises. The approach meant the quieter the surrounding environment became, particularly at night, the quieter the mill also had to be.
In 2023, the SDRC referred community complaints about the mill noise to the Queensland Department of Environment and Science after residents alleged industrial noise was disturbing their sleep, according to an Environmental Protection Order (EPO) issued by the department against the mill in 2023.
Department officers inspected the site and reported hearing the same types of noise described by residents. They concluded the complaints were neither frivolous nor vexatious.
Noise monitoring commissioned by the company later found the nearest affected residence experienced noise exceedances from operations including centrifugal silo fans, grain augers, conveyor systems and noise escaping through the roof structure. The department's own monitoring also identified repeated exceedances above background noise and concluded the operation was causing environmental nuisance.
The 2023 Environmental Protection Order required the company to engage an independent acoustic specialist, investigate every significant noise source across the site, model worst-case operating conditions and prepare a comprehensive noise assessment and management plan demonstrating how nuisance would be prevented.
Despite mitigation works undertaken by the company, complaints continued.
David Brown, Group Manufacturing Manager for Corson in Warwick, told the paper that he spends a lot of his time investigating and implementing noise mitigation. Mr Brown has an extensive background in manufacturing and describes the new noise ‘cameras’ that have been installed that allow the mill to better track and deal with excess noise.
“We understand it, and we want to be good neighbours,” Mr Brown said.
Nevertheless, an Environmental Enforcement Order issued in July 2025 alleged the company had contravened both its development approval and the Environmental Protection Act by causing unlawful environmental nuisance. The department ordered Corson to immediately cease delivery and dispatch vehicle movements between 4.30pm and 6am, reduce overnight noise, undertake further engineering works on the mill and complete six months of independent noise monitoring.
SDRC Changes to Conditions
While those enforcement actions were directed at securing compliance with the original development approval, an SDRC planning decision has fundamentally changed the way the mill's noise is regulated.
In July this year, SDRC staff approved a material change of use application by the mill which replaced the original 2018 background-based noise condition with fixed maximum noise limits. Despite the decision notice exceeding 60 pages, with council stating that “not all benchmarks have been complied with” the application was approved “despite non-compliance with the specific benchmarks listed” with explanations noted. One of those was “noise impacts” .
Instead of requiring the operation to remain within five decibels of the surrounding background noise at nearby homes, the amended conditions now permit fixed limits of 46dB(A) during the day and evening and 44dB(A) at night for most residences, regardless of how quiet the surrounding environment may be.
The practical effect is significant in rural areas where background noise is naturally low. On a quiet night with ambient noise of about 28dB(A), the original approval would have limited the mill to about 33dB(A). Under the revised conditions, noise of up to 44dB(A) is permitted—an increase of 11 decibels. Because the decibel scale is logarithmic, an increase of around 10 decibels is generally perceived as roughly twice as loud.
In busier locations where background noise is already high, the original conditions could permit similar or even higher levels. However, acoustically, the revised approval is generally more permissive in quiet rural environments because it no longer adjusts to existing background conditions.
“The applicant has demonstrated a willingness to mitigate noise impacts through the implementation of acoustic treatments,” the approval states. “It is also recognised that a High Impact Industry use inherently generates a level of noise.”
For residents, the issue extends beyond the technical detail of decibel limits: residents deserve to understand why planning conditions changed after years of environmental investigations and enforcement action.
Residents support local industry and recognises the importance of manufacturing to the Southern Downs economy, but significant amendments should be transparent and subject to public scrutiny.
“This was never sent to the councillors. The administration did it,” one resident said, explaining that when they contacted the SDRC, they were told that the application was “code assessable” and that they weren’t taking any responses from the community “because they don’t have to, it’s not impact assessable.”
The Southern Downs Regional Council has been asked to explain how the amended noise conditions were approved, whether the decision was made under delegated authority or by elected councillors, and how the revised conditions compare with those contained in the original development approval.
We await a response.
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