Treating Wastewater

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Raw wastewater from the City of Galt enters the wastewater treatment plant (WWTP) at the influent headwork’s structure, where items such as large debris are screened and off-hauled. The wastewater then goes through a grit removal process where sand, silt, and inorganic matter is removed and also hauled to a landfill.


From the headworks, the influent is sent to the secondary treatment splitter box, where it is diverted to the two oxidation ditches where a biological treatment takes place.

headworks splitter

The oxidation ditches is where the biological process takes place for the removal of organic wastes. Oxygen is added to the oxidation ditches, which is needed by microorganisms to grow and oxidize or eat organic matter in the wastewater.

Oxidation ditches

From the oxidation ditches, the treated wastewater is sent to the clarifier splitter box, where it is diverted to the two secondary clarifiers.

Splitter box

At the secondary clarifiers, the wastewater velocity is slowed down to allow solids to clump together and settle to the bottom as sludge. Any floating material or scum is removed from the surface and mixed with the settled solids (sludge). A calculated quantity of the clumped solids which contain microorganisms (return sludge) are returned back to the oxidation ditches to begin the treatment process again. Excess solids (waste sludge) are pumped to the sludge lagoons. The clarified wastewater flows out of clarifier through the launders (baffles).


The ag-gator (pictured below left) is a specifically designed vehicle for injecting the waste solids in the sub surface of the soil. The solids are injected in city owned farm land as nutrients to stimulate plant growth. The sludge lagoon (pictured below right) is where waste solids from the clarifiers are stored.

Sludge LagoonAgGator Loading 

The treated wastewater from the clarifiers is sent to the chlorine contact chamber, where chlorine is added to disinfect or destroy bacteria in the wastewater. To provide for sufficient time for the chlorine to work, the water flows through up to six channels in the contact tank, of which three can be seen here. When seasonally discharging to Laguna Creek the treated effluent is de-chlorinated to protect aquatic life.

Contact chamber

After leaving the chlorine contact tank, the treated effluent is sent to the effluent storage reservoir. Dependant upon the season dictates where the water goes from here.

Lowering res

During the irrigation season May through October, the treated effluent is used to irrigate crops on the City owned farm land.

Irrigated fields

 During the discharge season of November through April, the effluent is discharged to Laguna Creek after going through the cascade aerator, where the dissolved oxygen levels in the effluent are increased prior to entering the Creek.