Plant Information & Treatment Process

Wastewater PlantThe City of Vermillion Wastewater Treatment Plant was put into operation in 1985. Significant plant upgrades have been implemented due to increasing flows and changing state and federal regulations.

The plant is a secondary activated sludge facility and is designed to accommodate flows of two million gallons per day, with peak flows of up to four million gallons per day. Wastewater is pumped to the treatment facility from the City by two pumping stations.

Pretreatment Phase

The pretreatment phase is the first step of wastewater treatment. As wastewater enters the facility rags, debris, and gravel are removed. Primary clarification is the second phase of treatment. At this point, the heavy solids settle out of the water and the lighter solids float. The biological process is the next step of treatment. Microorganisms are used to treat the waste naturally. The organisms are concentrated in this process and mixing and aeration are provides as needed for high-rate treatment. 

The wastewater first flows over a redwood-media trickling filter and continues on to the activated sludge basins where it is mixed and aerated. The wastewater is then pumped to the final clarifiers where the microorganisms settle out and are returned to the treatment process. The treated wastewater then flows through the disinfection channel over cascade aeration to the river.

The excess microorganisms and solids produced by the process are treated by anaerobic digestion. This is done by heating and mixing the microorganisms and solids at 95 degrees Fahrenheit. They are then applied to agricultural land as fertilizer and soil conditioner. 

Services & Staffing

The Vermillion Wastewater Department has six staff members. The staff is responsible for the operation and maintenance of the plant facilities, laboratory operations, the sanitary sewer system, storm water pump stations and lift stations located throughout the City. 

There are several services that are provided by the Vermillion Wastewater Department: sewer taps for residential housing and businesses, locates for underground digging, checking for sewer odors inside buildings, cleaning of the City sewer lines, and inspecting City sewer lines by televising media. 


Visit the Utility Billing section for current wastewater rates, fees and other charges.


  • To help prevent sewer odors from entering your home, keep floor drains and water traps full of water year round.
  • Watch for snow or frost build-up over sewer vents on your house in the winter. If this would occur, pour hot water down the vent to remove the snow or frost. Please use caution when doing this because the roof may be slippery.