Sanitary Sewer Overflows and Wet Weather Events

Wet weather events, such as intense rainfall and/or snowmelts, often cause supersaturated soil conditions which can be attributed to inflow and infiltration of clear water in sanitary sewer collection systems.  While the sanitary sewer collection system is designed to accommodate an amount of clear water flow, when the amount of inflow and infiltration exceed the design capacity of the system, then bypassing occurs. Bypass pumping is set up when critical elevations in the sanitary sewer manholes or sanitary lift station wet wells are exceeded.  Suction is set at levels to bypass critical elevations to avoid basement back-ups. The City is continuing its efforts to reduce the amount of inflow and infiltration with ongoing sewer lateral work in addition to rehabilitation of the sanitary sewer mains and lift station improvements.

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Sanitary Sewer System Overflow due to Private Force Main Equipment Obstruction April 17

Due to equipment measuring hydrogen sulfide at the discharge end of a private force main failing and obstructing the flow in the sanitary sewer on Monday, April 17, 2023, the City experienced an overflow along Port Washington Road, which went into an adjacent ditch. The overflow did not go onto Port Washington Road. That ditch is located 3,400ft upstream of an unnamed tributary to the Milwaukee River.  Samples were collected and taken to a laboratory for analysis.

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Sanitary Sewer System Bypass Pumping During August 8, 2021 Wet Weather Event

Due to wet weather on Saturday night and into Sunday, August 8, the City experienced overflows at five lift stations, which required bypass pumping of the sanitary sewer system.  Bypass pumping is used to reduce basement backups and limit potential private property damage. The times varied for each station, but the duration can generally be described from approximately 2:30 A.M. to 8:30 A.M. on Sunday, August 8.   The following lift stations experienced overflows from the wet weather:

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Sanitary Sewer System Bypass Pumping During May 17, 2020 Wet Weather Event

Due to wet weather on Sunday, May 17, the City experienced overflows at nine lift stations, which required bypass pumping of the sanitary sewer system.  Bypass pumping is used to reduce basement backups and limit potential private property damage. The times varied for each station, but the duration can generally be described from approximately 1:30 P.M. on Sunday, May 17 to 3:00 A.M. on Monday, May 18.   The following lift stations experienced overflows from the wet weather:

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