Sewer Department

History of the Facility

The River Falls Wastewater Treatment Facility is a 1,824,000 gallon per day (gpd) secondary treatment facility. The facility at this site was originally built in 1963. The plant was upgraded to meet 30/30 effluent discharge limits in 1980. In 1996, River Falls joined with 10 other area communities to construct a regional sludge processing facility in Ellsworth, because of Department of Natural Resources new standards limiting land spreading regulations to only summer months.

The West Central Biosolids Facility produces a high quality class A sludge that has less restrictions on it because of the quality of the end product. In 1999 new regulations required the reduction of phosphorous being released into the waters of Wisconsin. A biological phosphorous reduction unit was constructed and put on line in March of 2000.

Primary Treatment System

Local wastewater is collected throughout the city by a collection system consisting of many miles of various size sewer mains and lift stations. The wastewater is transported to the treatment facility through the collection system and enters the plant through the primary treatment system.

Primary treatment consists of two-grinders/bar screen, four pump lift station, magnetic flow meter, primary static screens, dewatering screw conveyor, and a compactor.

Secondary Treatment Process

From the primary system, it flows to the secondary treatment processes, which include 2 parallel oxidation ditches and 2 final clarifiers. These facilities were all constructed during the 1980 construction season. Phosphorous reduction is accomplished in the biological selectors constructed in 1999. Chlorination is accomplished in 2 baffled units. These units were modified from the original final clarifiers in 1980. Dechlorination was added in 1989 when the DNR regulations reduced the amount of chlorine residual that could be released into the Kinnickinnic River. Dechlorination is accomplished by injecting sulfur dioxide into the effluent stream after chlorination and before the outfall to the river. Disinfection is required through the summer months.

Bio-solids Building

In November of 2016 the new solids handling facility went online. The building houses the DAFT unit (dissolved air flotation thickening), controls and pumps for all the plant solids handling and storage for the thickened solids. The DAFT allows for the solids to be thickened reducing the hauling costs to the Ellsworth facility. Covered storage for the thickened solids was added to eliminate the need to haul excess water from precipitation and control odors. The new facility has allowed for improved maintenance, greater operational control, a more efficient mixing system and reduction of odors.