The Dornick Point Wastewater Treatment Plant, provides wastewater treatment to 20 municipalities and nearly 100,000 people in the greater Johnstown, PA, area. The plant provided primary treatment from its construction in 1961 until a $30 million upgrade in 1992 when an activated sludge secondary treatment system was installed.
The upgrade was first conceived in 1976 when the U.S. Environmental Protection Agency ordered the upgrade, but the project was delayed indefinitely following the catastrophic flood of July 19-20, 1977. Finally in 1987, EPA and the city negotiated a consent decree to install secondary treatment. Johnstown delegated the construction and financing project to the Redevelopment Authority, which now owns and operates the plant.
Note: this page follows wastewater as it enters the plant and proceeds to discharge in the Conemaugh River. There are numerous additional processes involving recycling and sludge processing.
Wastewater enters the headworks through a 60-in. (1500-mm) pipe that can handle flows as high as 27 mgd. Typical plant flow ranges between 8 and 10 mgd.
From the headworks, the flow goes through a 3/8” mechanical bar screen and then to an aerated grit basin where inorganic materials settle out. These materials are then washed and deposited into a dumpster along with the mechanical bar screenings for landfill disposal.
Four 100 HP pumps are used to pump the raw sewage to an aeration tank. The secondary process is a pure oxygen activated sludge system. Due to the small size of the treatment plant site, the aeration tank is one-fifth of the size necessary to properly treat sewage utilizing atmospheric air for aeration, so pure oxygen is used for aeration. This accelerates the activated sludge process. The plant utilizes cryogenically produced liquid oxygen that is delivered to the plant on a regular basis in tanker trucks. Daily usage is 5-10 tons per day, dependant on the water temperature.
Following aeration, four rectangular clarifiers that were converted from primary to secondary clarifiers, and a 100-ft diameter circular clarifier that was built during the upgrade to secondary treatment, allow solids to settle out.