Wastewater System

The heart of GAUD’s wastewater treatment system is an activated-sludge secondary treatment plant located along the Kennebec River Rail Trail at 33 Jackson Avenue. It treats an average of 4 million gallons per day (MGD) of wastewater, with flows reaching 40 MGD during rainstorms. 

This requires large and expensive equipment, especially pumps, and a multi-step process:

  • The wastewater comes from thousands of homeowners, commercial establishments and industries in Augusta, Hallowell, Manchester, Monmouth and Winthrop. It is collected through a system of underground pipes that flow into a wastewater collection system. 
  • The collection system sends the wastewater to pumping stations throughout greater Augusta, and six “trunkline” pumping stations in the towns outside Augusta, which convey the wastewater to the treatment plant from the east and west sides of the Kennebec River through large pipes called "interceptors."
  • As a first step at the wastewater facility, metal screens with automatic raking systems remove most of the large "stuff."
  • Next, a grit separation system is used to help remove sandy, heavy materials.
  • The water then flows to the primary clarifiers which allow solids to settle out, leaving cleaner water to flow to the aeration tanks. These provide oxygen for bacteria that we want to grow, so they can enlarge and settle out in the secondary clarifiers. (Our site is footprint-limited, so the aeration tanks must be very small, which requires pure oxygen.)
  • The tanks provide a second means of clarification, which removes even more solids from the wastewater. 
  • In the winter, the water from the secondary clarifiers flows into the Kennebec River with no further treatment.  In the summer, the water is treated with a disinfectant to kill remaining organisms in the water.  Then the disinfection chemical is removed before the water is discharged to the Kennebec. 


Our process to treat wastewater can be boiled down to six simple steps: collect, screen, settle, add air, settle again, disinfect, discharge. But the process requires hundreds of miles of pipe, and many tons of sophisticated equipment, which needs frequent monitoring, maintenance and repair, by highly skilled personnel.

Keeping it clean!

Wastewater treatment is closely regulated under the Clean Water Act and enforced by the Maine Department of Environmental Protection. Click here for a copy of the Greater Augusta Utility District's Sewer Use Ordinance.