Sugar plant seeking to renew discharge permit
OLIVIA -- The Southern Minnesota Beet Sugar Cooperative remains unable to meet water quality standards, but Renville County may be asking that it return to sending its treated wastewater into Beaver Creek via County Ditch 45 when it renews its wastewater discharge permit this year.
That would be welcome news to landowners downstream of the Renville factory along County Ditch 37 and Sacred Heart Creek, where the company now discharges its treated water. Ever since the company was required to send its discharge their way in 2004, they have been concerned about the potential for ice jams and farm field flooding.
A return to using County Ditch 45 would be welcomed by the sugar processing company as well, according to Louis Knieper, manager of environmental affairs for the cooperative.
He told the Renville County Board of Commissioners on Tuesday that using the smaller capacity of County Ditch 37 forces the company to hold back on the water it discharges as ice and snow fill the ditch in the latter weeks of its processing campaign. That means it must store larger volumes of treated wastewater in its on-site ponds. That raises the potential for foul-smelling emissions of hydrogen sulfide, and can slow down the campaign itself.
The plant can discharge up to 1.5 million gallons of water per day during the September-through-March sugar beet processing campaign.
Knieper said the company is now in the process of seeking a new discharge permit. It has not formally asked the Minnesota Pollution Control Agency about returning to County Ditch 45.
The Southern Minnesota Beet Sugar Cooperative has made major strides in reducing its environmental impact since it was granted a variance to discharge its wastewater into County Ditch 37, according to Knieper.
But the company continues to discharge wastewater with higher salinity than allowed, which is why the MPCA originally requested that it switch its discharge from Beaver Creek to Sacred Heart Creek. The agency wants to protect Beaver Creek. It has more aquatic life and a greater use potential for recreation, crop irrigation, and as a water source for cattle than the smaller Sacred Heart Creek.
Since 2004, Knieper said the cooperative has achieved a "big reduction'' in the salinity of its discharge. The salinity is measured by its electrical conductivity, and that has dropped from 7,000 to 4,000 micromhos per centimeter of water.
"I don't believe we're going to go much below that,'' Knieper said. Other options to desalinate the effluent are cost-prohibitive, he said.
Nonetheless, the company is looking at investments to improve its water discharge. It has started design work to add a five-acre water retention pond. It would be built adjacent to the wastewater treatment plant and used to hold the treated water for six days before discharging it. For reasons neither the company nor some of the nation's leading laboratories can identify, the toxicity of the plant's discharge to the tiny aquatic daphnia used for water quality testing decreases significantly if the water is held for six days, according to Knieper.
The company's wastewater treatment plant has allowed the company to meet all other water quality requirements, such as biological oxygen demand and ammonia discharge limits. By the time the treated water in County Ditch 37 mixes with the water from the east branch of Sacred Heart, there is no statistically discernable difference in the impact on aquatic life, according to Knieper.
He also credits the wastewater treatment plant with helping the company greatly reduce on-site water storage. That has led to a dramatic drop in air emission violations caused by decomposition in the ponds.
Violations for hydrogen sulfide emissions fell from what Knieper called an "embarrassment'' of more than 1,100 incidents in 2001 to less than a handful today.
The wastewater plant has also made it possible for the company to reduce the amount of wastewater spray irrigated on land, and prevent nitrogen overload problems.
All of these improvements have not gone unnoticed, said Diane Mitchell, water and household hazardous waste director for the county. She and Larry Zupke, county ditch inspector, pointed out that having adequate capacity to maintain wastewater treatment flows by returning to County Ditch 45 could benefit water quality while reducing downstream flood risks.