on Plant Discharges
Following the passage of its enabling act in 1984, MWRA assumed
responsibility for MDC water and sewer systems.
A. David Mazzone ordered 13-year schedule to construct new Deer
Island Treatment Plant (DITP) and related facilities.
Interim repairs and upgrades to the old DITP included the provision
of a more reliable disinfection system. Also, sewage scum was
landfilled instead of being discharged into the harbor.
Scum removal left less oil, grease, and floating matter in effluent.
Better disinfection resulted in fewer
Pumping capacity increased from about 700 million gallons per
day (mgd) in 1989 to 900 mgd in 1998.
Increased volumes of wastewater treated and CSO discharges reduced.
Sludge discharges into the harbor from the old Deer and Nut
Island treatment plants ended. Sludge-to-fertilizer pelletizing
began at the Fore River plant.
Solids discharged to the harbor decreased by 40 dry tons per
day. Decreases in biochemical oxygen demand (BOD), nitrogen
(N), phosphorous (P), and bacteria.
First components of improved primary treatment put
into service at the new DITP.
Drop in total solids discharged, as well as further decreases
in bacteria, BOD, N, and P.
Startup of Battery A, the first of three batteries of secondary
treatment at DITP.
The beginning of secondary treatment marked dramatic decrease
in BOD and continuing declines of bacteria, solids, N, and P.
Battery B of secondary treatment started up at DITP.
completed. South System flows transferred to DITP from the Nut
Island Treatment Plant (NITP), allowing most flow to receive
secondary treatment. NITP was later demolished, and replaced
by a headworks facility and a park.
Start-up of new ocean outfall diffuser; effluent now discharged
through a 9.5-mile outfall into Massachusetts Bay.
End of effluent discharges to Boston Harbor; effluent receives
much better dilution in the bay.
Last battery of secondary treatment placed in operation at DITP.
Treatment optimized at DITP. Discharge consistently meets effluent