Highwater Ethanol, LLC (Highwater) owns and operates an ethanol production facility in Lamberton, Minnesota. The ethanol plant has four fermenters and one beer well (Fermentation Units). A carbon dioxide (CO2) scrubber controls volatile organic compounds (VOC) emissions from the Fermentation Units. The on-site inspection conducted by EPA using an optical gas imaging camera as well as audio, visual, and olfactory observations revealed uncaptured VOC emissions from the Fermentation Units from components on the top of Highwater's fermenters and beer well.
Specifically, Highwater failed to:
(1) properly maintain components that are part of the Fermentation Units, including pressure relief valves/vacuum breakers and agitators, that have the capacity to vent fermentation emissions uncontrolled directly to the atmosphere;
(2) capture emissions from its Fermentation Units. Since at least June 29, 2018, Highwater emitted more than 10 pounds per hour of VOCs from the Fermentation Units; and
(3) vent all emissions from the Fermentation Units to the CO2 scrubber.
Highwater has implemented corrective action to mitigate the alleged violations, including:
(1) replacement or rebuild of all pressure relief/vacuum breakers atop the fermenters and the beer well by August 21, 2018;
(2) replacement of the vapor sealing barrier on the shaft of each agitator atop the fermenters and the beer well by August 22, 2018; and
(3) initiated emission monitoring of pressure relief valve