The City of Watertown wastewater treatment plant was designed by

Brookfi eld, Wisconsin ● (262) 784-7690 ● www.ati-ae.com

• The treatment plant construction was bid in 2002 for a cost of $23.6 million.

• Major interceptor work associated with the new plant was constructed separately for a cost of $3.6 million, including a new 5-foot diameter interceptor on Hoffmann Drive and a 4-foot diameter interceptor crossing the Rock River.

• The construction was fi nanced by a low interest loan from the Wisconsin Clean Water Fund.

• The treatment plant can treat 5.2 million gallons on an average day, up to 24 million gallons on a peak day.

• Annually, the plant can treat and return enough highly treated water to the Rock River to fi ll a 500-acre lake to a depth of almost 12 feet.

• The combined holding capacity of all of the tanks totals 5.6 million gallons, which is equivalent to a football fi eld fi lled to a depth of 13 feet.

• The City is underlain by 105 miles of sewers collecting wastewater from an area of 12 square miles; the collection system includes 19 lift stations.

• The treatment plant is equipped with its own emergency power generator to keep the plant running in the event of a power failure; the 2 MW generator can provide enough energy to power up to 100 homes.

The Facts

(1) Wastewater entering the plant is collected in the Raw Sewage Pump Station.

(2) It is pumped up to the Primary Building for screening to remove coarse debris.

(3) The screened wastewater fl ows to grit chambers to remove heavy particulate matter like sand and gravel.

(4) Primary clarifi cation is next, where the wastewater undergoes gravity settling to remove solid pollutants; about one-third of the treatment work is completed after this stage.

(5) The wastewater then fl ows to the aeration basins, where a mixture of naturally occurring microbes consume dissolved pollutants.

(6) Final clarifi ers remove the microbes, leaving highly treated water cleansed of more than 99% of the pollutants.

(7) The water is disinfected with ultraviolet light to kill bacteria and viruses.

(8) The water cascades through an aerator just prior to release into the Rock River.

(9) Residual materials from the treatment process are collected for reduction and stabilization through fermentation in digesters.

(10) The digested residuals are further reduced through dewatering centrifuges.

(11) Dewatered residuals are stored as cake prior to being used as an agricultural soil conditioner.

(12) Plant administrative, operations and laboratory facilities are housed in the Administration Building.

(13) Plant maintenance functions are housed in the Maintenance Building.

Wastewater Treatment Process

Do you have questions about the City of Watertown wastewater treatment plant? Would you like a plant

tour? Please contact us at (920) 262-4085.

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What is wastewater and why is it treated?Every time you use water to take a shower, wash the dishes, do the laundry, or fl ush the toilet, the used water becomes dirty wastewater that drains away via the sewer system. Wastewater from homes, businesses, and industries contains pollutants that can harm the environment and threaten public health. Therefore, it must be cleansed of contaminants before being returned to our rivers and lakes. The jars displayed along the side of the page show wastewater at various stages of treatment, indicating what the treatment process accomplishes: returning safe, highly treated water back to the environment.

Laboratory TestingProtecting our Environment

The Wisconsin Department of Natural Resources (WDNR) and the United States Environmental Protection Agency (EPA) have rules governing the treatment of wastewater that establish standards for the quality of water returned to the environment. The laboratory routinely tests samples of wastewater to ensure that the plant is meeting these standards. On a daily basis, the laboratory performs approximately 100 tests on a variety of samples to monitor the health and performance of the plant. The results are reported to the WDNR each month in accordance with State laws. Ultimately, all of the testing is done to preserve and protect our environment.

Treatment Plant HistoryThe City of Watertown, located along the banks of the Rock River on the border between Dodge and Jefferson Counties, obtained its charter in 1852. The fi rst sewer construction in the City dates back to 1895.

The fi rst wastewater treatment plant, designed to treat 1.8 mgd, was placed into service in 1933 on an island in the Rock River to address public health concerns and nuisance conditions in the river. The plant was expanded up to a 2.5 mgd capacity in 1955, and further expanded up to 5.2 mgd in 1980. Twenty years later, due to the plant’s age and more stringent requirements for discharging to the Rock River, the City undertook a comprehensive Facilities Plan. Completed in 2000, the Facilities Plan recommended that a new treatment plant be constructed on a new 40-acre tract adjacent to the old plant site.

Design of the new facilities took place in 2001, with construction commencing in 2002. Completed in 2004, the new 5.2 mgd plant is designed to meet the City’s needs through the year 2024. The treatment plant site will accommodate future growth well beyond the next twenty years.

Recycling – Processing and Disposal of Biosolids

In the wastewater treatment process, a mixture of naturally occurring microbes consumes the pollutants and purifi es the water. As the treatment progresses, an excess of microbial solids is produced, called biosolids. The biosolids undergo a fermentation process to stabilize the material, killing potential pathogens and reducing odor potential. The fermentation process produces methane gas as a byproduct, which is burned in boilers to produce the heat needed for fermentation. The treated biosolids are next dewatered to form a “cake” for storage.

The fi nished product is rich in nutrients and organic material similar to peat, making it an excellent soil additive for agricultural use. It is tested extensively to make certain that all WDNR and EPA regulations governing biosolids use as a fertilizer are met. The material is then spread on farm fi elds in the fall and spring, depending on land availability. The recycling of biosolids to agricultural lands represents an

environmentally sound use of resources.

Plant OperationTreatment plant staff perform the daily tasks required to maintain optimal plant performance. The operators need accurate data to monitor the status of plant components, making certain that all of the various processes are running effi ciently. Electronic sensors are strategically placed throughout the plant to monitor and control its state. A computer in each building collects data from the sensors, communicating through a fi ber-optic system with the main Control Room in the Administration Building. From the Control Room, the operators can observe the status of the entire plant. The information provided through the computer system allows the operators to make decisions about adjusting plant controls and scheduling equipment maintenance.

Trained operators ensure that the plant runs at peak effi ciency.

This building stores treated biosolids, which form a “cake.”

Raw Sewage

Primary Effluent

Secondary Effluent

Final Effluent

Highly treated water is returned to the Rock River.

The City’s fi rst sewer line being laid in 1895.

Photo courtesy of the Watertown Historical Society. www.watertownhistory.org.