Mount Dora study IDs likely source of pungent mystery smell

Yahoo

09-05-2025

The source of a mystery stench that has plagued Mount Dora residents and visitors for years may finally have been identified by consultants for the city and Lake County.
Now the question is what to do about it.
According to the consultants' 83-page report, funded by a combined $270,000 from the two local governments, the Mid Florida Materials Mount Dora landfill on State Road 46 is likely generating the hydrogen sulfide gas that gives off the pungent odor.
The study exonerates the city's sewage treatment plant, while also noting weather patterns in the area worsen the problem.
'The Mid Florida Mount Dora landfill has the most significant impact on odor conditions in the study area,' the report concluded. 'It is further observed that calm wind conditions prevent dispersion, allowing foul odors to accumulate in the area, resulting in more severe odor conditions.'
The study addressed 'odor conditions and likely odor sources' near ground zero for the stink: Sullivan Ranch, Stoneybrook and areas close to the junction of U.S. 441 and SR 46.
City officials chose consulting firm Halff to lead the study, with California-based V&A Consulting Engineers subcontracting to help complete background reviews and project management duties, among other tasks.
'The final report, V&A was able to determine, as we expected, that the odor was not being emitted from any of our facilities but from the landfill,' Andrew Marsian, Mount Dora utilities & plant operations director, said. 'We have a meeting next week with some of the stakeholders to decide the best approach with this moving forward.'
Investigators acknowledged the disposal site — described as a 'construction and demolition landfill' — was not fully accessible during the study and that all observations were conducted from the perimeter of the site.
Mid Florida Materials issued a statement pledging to review the findings. 'Our facility has been and remains in full compliance with applicable air quality regulations, and we will address any concerns of the DEP,' it read.
The investigators identified several aroma hotspots within the landfill property, including retention ponds, vents and the landfill 'working face' — the location where waste is dumped, deposited, compacted, and covered.
While specific sources of hydrogen sulfide were not named, demolition landfills can include drywall waste, which often contains sulfur that emits a rotten-egg smell when wet.
The report also included a number of 'weak' odor sources observed during the study, including odors emanating from the Curaleaf cannabis facility on Britt Road and Goldflower Cannabis facility on Niles Road.
A 'slight odor' was detected at both facilities that was later identified as cannabis and 'not similar to the odors observed in the study area'. The cannabis facilities were determined as 'unlikely' to cause the persistent foul odor that led to the study.
Over the years, multiple locations have been suspected as the source of the stench, particularly the landfill and the city's wastewater treatment plant along James P. Snell Drive off U.S. 441.
Mount Dora then took steps to help rectify the situation, including the installation of a $500,000 carbon biofilter in 2022 and the addition of monitors to detect hydrogen sulfide at its wastewater treatment plant in March 2023.
But the smell persisted and the Florida Department of Environmental Protection issued a consent order requiring the city ramp up odor mitigation efforts in November 2023.
An initial study, authored by consulting firm Kimley-Horn, indicated the odor is 'highly unlikely to be coming from the wastewater and collections system' but left unsaid what the culprit might be.
Mount Dora councilmember Cal Rolfson said he believes this most recent study fully clears the city of responsibility for the smell, allowing city officials to move forward with DEP and focus on alleviating the odor for good.
'This vindicates the city of Mount Dora, in my opinion, with clear and convincing evidence that states it is not our problem and not our issue,' Rolfson said. 'But it is our issue in terms of needing to work with [FDEP] and do something about this. The smell comes into our city and therefore we have some responsibility to make sure responsible parties are contacted and that we deal with them appropriately and legally.'
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