Oronoco, the largest unsewered city in Minnesota, to build wastewater treatment facility

Contact: Cathy Malakowsky, 507-206-2608

The Minnesota Pollution Control Agency has released its draft permit and environmental assessment worksheet for the City of Oronoco’s proposed wastewater treatment plant. Oronoco, with a population of about 1,300, is the largest city in Minnesota without a municipal sewer system. The proposed system would replace individual and community sewage treatment systems, many of which are failing to protect groundwater, do not meet setback requirements, and/or have exceeded their life expectancy.

The project would consist of the treatment facility, a sanitary sewer lift stations and lines, drinking water mains, and riverbank stabilization along the Zumbro River. The new treatment plant would be built on Minnesota Avenue South, just outside the city in Oronoco Township, on land currently used for cropping. The plant would discharge to the Middle Fork of the Zumbro River, immediately downstream of the city.

Once the facility is operational, the city would decommission 11 community drain fields and one pond treatment system used for a mobile home community. Residences with individual sewer treatment systems would be responsible for decommissioning their own systems.

Project innovations

Oronoco’s project would use riverbank stabilization to offset phosphorus in the treated discharge from the wastewater facility. River stabilization would help keep soil — and phosphorus attached to it — from eroding into the river and degrading water quality in Lake Zumbro. Phosphorus can cause algae, which negatively effects fish, other aquatic life, and recreation. The discharge from the wastewater treatment plant will contain phosphorus but the stabilization project will reduce phosphorus in the river by a comparable amount, resulting in no net increase.

In addition, Oronoco will be the first Minnesota city to enroll in the state’s regulatory certainty program. Under this program, a city implements wastewater treatment systems that reduce nitrogen in its wastewater discharge, though the state has not yet adopted a water quality standard for nitrogen. Nitrogen in water makes it unsafe to drink, toxic to fish, and prone to algae growth. By taking action on nitrogen, the cities are assured of no new nitrogen and phosphorus limits in their MPCA wastewater permit for 20 years (the life expectancy of most facilities).

State law mandates both an environmental assessment worksheet and a wastewater discharge permit for this project. Both the worksheet and the wastewater permit are open for public comment. State agencies use the worksheet to help decide whether a project requires a more extensive environmental impact statement. The worksheet describes the project’s potential effects on nearby land uses, geography, bodies of water or groundwater, wildlife and habitat, and historic sites. It also details air and vehicle emissions, dust, traffic, noise, and odors that the project might produce. The MPCA issues wastewater discharge permits to put limits on the amount of pollutants discharged to the environment from treated wastewater.

The Minnesota Pollution Control Agency (MPCA) will hold a public information meeting on the environmental review and draft permit on Thursday, Dec. 5, at the Oronoco Community Center, 115 Second St. NW, starting with an open house at 6:30 p.m. Presentations will follow at 7 p.m. with time for questions.

The environmental assessment worksheet is open for comment through 4:30 p.m. on Wednesday, Dec. 18 and available to read on the MPCA web site. Email or mail comments to Kim Grosenheider, MPCA, 520 Lafayette Road N., St. Paul, MN 55155-4194. For more information, contact her at 651-757-2170.
The draft permit is open for comment through 4:30 p.m. on Friday, Jan. 17 and available to read on the MPCA web site (scroll to “Monday, November 18, 2019”). Email or mail comments to Melanie Miland, MPCA, 18 Wood Lake Drive SE, Rochester, MN 55904. For more information, contact her at 507-206-2647.