Foul odors have been plaguing neighborhoods adjacent to the brand new Diageo distillery for the past week, which the company attributes to venting problems in methane-generating waste digesters that process the molasses dregs left over from making rum.

"We have been hearing complaints since the 12th," Planning and Natural Resources Public Information Officer Jamal Nielsen said Thursday. "We are doing an internal investigation and a notice of violation is likely. But they have at least been telling us what is going on," he continued.

Complaints came in through Oct. 18, and subsided Wednesday, Nielsen said. "They say they had some problems, had to shut down some tanks and are trying to work on a solution." Complaints predominantly came from neighborhoods near the distillery, such as Estate Profit, Bethlehem Village, Clifton Hill, and the Harvey housing community, Nielsen said.

Diageo Vice President Dan Kirby said Thursday the company has applied some temporary mitigating measures and is working on a permanent solution. The problem arose in small, passive vents in molasses digesting tanks, he said.

"Over the last week or so, something has dislodged some of the material underneath – we call it pillowing – that popped open the vents, releasing odors before they popped down again."

The vents are designed to be held closed partly by the vacuum created by exhaust fans that pull out the methane and other gases produced in the digestion, but the system is more effective at producing methane gas than they had anticipated.

"So we had to increase the speed of the fan, which was set too low," Kirby said. "That helped to pull down the covers, but there is still some pillowing, so we put water on top to hold them down for now."

The equipment manufacturer is coming in to inspect the system and put in more passive vents, "so if it happens again we can actually direct the vapors to a control system, such as a carbon filter or gas scrubber," Kirby said.

This is the second rash of odor complaints since the plant opened less than a year ago. In May, a large tank of fermented molasses wash called "vinasses" sat in a large buffer tank over a long weekend and decomposed in an uncontrolled fashion creating foul fumes.

As with the May incident, Kirby apologized for the odors and attributed them to "start-up issues."

"We have been at it for only eight months and it takes a little time to work through the mechanics of the plant," Kirby said Thursday.

"We have put in mitigating solutions, but want the OEM (original equipment manufacturer) to come in with a more permanent solution,” Kirby said. “I don’t want them doing what they did again.