Seeking to meet mandated cuts for the discharge of nutrients into the nation’s largest estuary, the Chesapeake Bay, a Maryland wastewater treatment plant and its design, construction and technology team are using what they say is the world’s largest application of a pollutant-reduction technology as part of a $138.7-million facility upgrade. Team officials at the Patapsco wastewater treatment plant in Baltimore say use of the “fixed-film denitrification system” for tertiary treatment at the facility will reduce nitrogen and phosphorous discharges into the Patapsco River by 83% and 85%, respectively. The waterway is a key tributary of the bay, now on
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.