Granite Falls Energy LLC - Wastewater Permit

We invite you to comment on the draft industrial wastewater permit for Granite Falls Energy’s ethanol facility in Granite Falls.

Granite Falls Energy, LLC operates a dry mill ethanol production facility with a capacity to produce 70 million gallons per year of undenatured ethanol.

The facility discharges industrial stormwater to a series of unnamed wetlands, ditches, and unnamed creeks that eventually flow to the Minnesota River. Hydrostatic testing water discharges for new equipment may occur.

Outfall SD 001, which the permittee previously maintained in this permit as a contingency plan for discharge of utility wastewater, is being discontinued since it is no longer needed. The draft permit includes closure requirements for SD 001.

The draft industrial wastewater permit adds effluent monitoring for nitrite plus nitrate, total Kjeldahl nitrogen, and total nitrogen and requires increased monitoring frequencies for ethanol and gasoline-range organics to obtain more representative sampling. The permit also adds annual monitoring for 40 PFAS compounds because the EPA and MPCA have identified ethanol manufacturers as facilities with a higher likelihood of releasing PFAS into the environment.

Wastewater from industrial and commercial sources may contain pollutants at levels that could adversely affect the water quality in area wetlands, streams, rivers, and lakes. Water quality permits - or National Pollutant Discharge Elimination System (NPDES) permits - establish specific limits and requirements to protect Minnesota's surface and groundwater quality. All wastewater must be treated before it goes into surface water to protect human health and aquatic life. Permits are regularly reviewed and updated as they expire, allowing the MPCA to incorporate new information about the impacts of pollutants on the environment in future permits.