Minnesota fines Morris ethanol plant $22,141 for water pollution

In Minnesota, DENCO II LLC, an ethanol plant in Morris, has agreed to pay a fine and take steps to prevent discharges of polluted stormwater and wastewater into nearby surface waters, including wetlands that drain to the Pomme de Terre River. The company also agreed to correct several other problems following an investigation by the Minnesota Pollution Control Agency (MPCA).

The company’s discharge permit allows the plant to release stormwater and wastewater containing limited concentrations of various pollutants to nearby surface waters. The plant discharges directly to an 8.1-acre wetland complex that flows to the Green River and then the Pomme de Terre River roughly a mile from the facility.

An MPCA investigation into records and practices revealed violations of the permit that included failure to adequately monitor, report, and correct discharges containing excessive amounts of organic material, total suspended solids, disinfectants used at the plant referred to as “residual oxidants,” as well as other pollutants. High levels of organic matter, such as dust from corn and distillers grains, can lower oxygen levels in waters into which they flow. Residual oxidants can include chlorine and bromine that are harmful to fish and other aquatic life. Records indicate these problems occurred between May 2010 and January 2018.

Other violations identified included missing records, insufficient and too few stormwater site inspections, monitoring deficiencies, water sampling quality control deficiencies, inadequate equipment calibrations, and other problems with documentation, reporting and operational controls.

In addition to paying a penalty of $22,141, the company agreed to take numerous other actions to correct problems. Some involve achieving the requirements of a schedule of compliance already in place to have the facility eventually meet effluent discharge limits for various types of dissolved salts that can be harmful to aquatic life. Currently, the facility discharges levels that can be harmful downstream.