The purpose of the proposed project is to improve the city of Ogilvie’s wastewater treatment facility. There have been no significant upgrades to the equipment or the treatment process in nearly three decades and, while still functional, the facility has aged and requires upgrades to continue long-term operation and to meet Minnesota Pollution Control Agency’s (MPCA) recently updated mercury and phosphorus limits.
The city must upgrade its facility to replace equipment that is at the end of its useful life. Operators have attempted to optimize effectiveness and efficiency, but many components at the facility have reached the end of their service life. Overall, the structures and equipment at the wastewater treatment facility have deteriorated to the point where architectural or structural repair, such as concrete patching, is required on every structure. The concrete walls on the sludge drying beds, constructed in 1954, are crumbling and complete removal and replacement of the beds is needed. Additionally, the facility is no longer able to meet the demands of the city. Excessive inflow and infiltration have resulted in calendar month flows higher than design capacity. The existing well does not provide sufficient water capacity and pressure for the facility therefore a new one must be drilled.
MPCA is imposing both total phosphorus and mercury limits on the effluent from the Ogilvie wastewater treatment facility. These limits are established to protect the water quality of the river and public health. Phosphorus can cause increases in algae production in surface waters which can be detrimental to aquatic life. Mercury accumulates in fish which may be consumed by humans, resulting in potential health effects. The MPCA has included a Compliance Schedule in Ogilvie’s National Pollutant Discharge Elimination System (NPDES) discharge permit that requires the city to provide annual reports on efforts to reduce phosphorus and mercury. The NPDES permit required compliance with the proposed effluent limits by May 2021. In order to meet these effluent limits, the city of Ogilvie must implement improvements to their wastewater treatment facility to reduce levels of both phosphorus and mercury.