Process Information

Main Treatment Facility Process Overview

The main treatment plant is an activated sludge facility designed to handle all dry weather flow up to 5 million gallons per day (MGD), with a peak daily flow of 8 MGD and a peak pumping capacity of 15 MGD. Take the virtual process tour for more details.

You may also watch a recorded webinar on the process.


The plant process includes phosphorus removal, screening, grit removal, primary treatment, secondary treatment, anaerobic digestion of solids, and disinfection. Sludge is treated by anaerobic digestion followed by belt filter press dewatering.

The Process

Screen Building	Grit Chambers	Pump Building
The screen building removes large debris from the wastewater as it enters the facility.	Heavy materials, like sand, settle out in the grit chambers.	Since the treatment plant is primarily a gravity fed operation, the wastewater needs to be pumped up to the primary tanks.
Primary Settling Clarifier	Blower Chemical Building	Aeration Tanks
Primary settling removes suspended solids.	The BCB houses the aeration equipment for the aeration tanks.	The aeration tanks provide a well-oxygenated environment for microorganisms.
Final Clarifiers		Digester Building and Belt Filter Press Building
These clarifiers allow for the final settling and removal of solids prior to disinfection and discharge of the wastewater effluent.		The solids from the final clarifier that are not recycled back into the system are sent to the digester for further microbial processing. After the digesters the remaining sludge is sent to the belt filter press for dewatering and disposal.

The Combined Sewer Treatment Plant for District 2 (CSTP No.2)

CSTP No. 2 is used to handle high rates of flow that exceed the main plant’s design capacity, such as in the spring when snow melting occurs or during major rain events. This facility has a 50 million gallon aerated storage basin and is designed to contain a ten-year storm. CSO No. 2 can treat 25 MGD of combined wastewater with a peak pumping capacity of 60 MGD.

CSTP No. 2 Screen Building and Contact Tank

CSTP No. 2 Lagoon