The effluent from the secondary treatment process is discharged into the chlorine contact basins.
Excess chlorine is removed with the chemical addition of sodium metabisulfite.
This is to protect sensitive aquatic organisms in the Lynn Harbor. During the non-chlorination season, the effluent merely passes through the chambers and is discharged to the Lynn Outer Harbor. The Outer Harbor discharge line is capable of allowing 73.3 million gallons per day of treated wastewater to be discharged. Any effluent flows that are greater than 73.3 MGD are discharged to the Lynn Inner Harbor discharge line.