Treatment Plant/Collection System

The original collection system was installed in the 1880s.  The Norwalk wastewater treatment facility was installed in 1931 and has continued to expand and advance.  In the 1950s, the facility was upgraded with additions and alterations to various equipment and processes.  Primary treatment was added in the 1960s and in the 1970s the plant was upgraded to secondary treatment with activated biological treatment. In the 1980s, additional wet weather treatment and pumping systems were added.  In the 1990s, additional treatment technologies were added for biological nutrient removal (BNR) as part of the Long Island Sound Conservation and Management Plan. In 2012 the CSO/Wet Weather Preliminary Treatment building went online and in 2020 improved chlorination and dechlorination was added to wet weather treatment.

To download the process flow schematic click the link below:

To view or download a copy of our NPDES permit click the link below: