Contact: Daniel Olson, 218-846-8108
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.
According to the schedule of compliance, facility discharges must meet permit limits for salts (as measured by total hardness, total dissolved solids and specific conductivity) no later than by the end of 2020. The facility plans to switch its facility water supply from onsite groundwater wells to treated water from the city of Morris once the city constructs a new water supply treatment plant. Using treated city water will make it easier for the ethanol plant to meet the permit limits for hardness and other salts in its discharge water.
The penalty and required actions are part of a stipulation agreement with the MPCA to achieve the plant’s compliance with environmental laws. When determining penalties, the agency takes into account how seriously violations affected the environment, the number of times the plant has received penalties for similar violations, and also how promptly violations are reported to appropriate authorities. The process also attempts to recover the calculated economic benefit gained by the plant’s failure to comply with environmental laws in a timely manner.