City of Saginaw, Michigan

The design flow of the Saginaw Wastewater Treatment Facility is 32 million gallons per day (MGD). We have a "Combined Sewer System" in which sanitary, industrial and stormwater flow into the same sewer lines. The plant site encompasses approximately forty acres with sixteen buildings. The three main buildings are connected by underground tunnels.

Wastewater flows to the treatment plant primarily by gravity, through sewers ranging in size from 8 inches to 10 feet in diameter. There are approximately 300 miles of sewer lines buried beneath the streets and other areas of the City and parts of areas outside the city limits.

Some low areas have pumping stations to lift wastewater up into another sewer so that it can again flow by gravity to the Wastewater Plant for treatment.

The interceptor (main sewer pipe) conveys the wastewater to the treatment plant, where it enters the raw sewage wetwell approximately 50 feet below ground level. After passing through a coarse barscreen with 3 inch openings, the water is pumped to an elevation several feet above ground level, enabling, under normal conditions, gravity flow through all plant processes, including discharge to the Saginaw river.

When high river water levels, or high hydraulic loading rates through the treatment plant prevent gravity discharge to the river, pumps are available to lift the water again, to allow gravity flow to the river. The river discharge point is at the bottom of the river, in the center of the shipping channel.

A treatment plant uses a series of stages to clean the wastewater before allowing it to be safely released to a lake, river or stream.

Treatment at the Saginaw Wastewater Treatment Facility consists of two major steps. These steps are Primary Treatment and Secondary Treatment. Along with these major treatment processes, the residual left by these processes (bio-solids, more commonly called sludge) also has to be removed. Before the water is discharged to the river, it is also treated with chlorine to kill harmful organisms (pathogens).

The cleaned and disinfected water is then treated to remove excessive chlorine, which could be harmful to aquatic life.


Sanitary ( households) 7.2 MGD
Industrial & Commercial 10.3 MGD
Stormwater & Infiltration 7.5 MGD
Total 25.0 MGD