Opportunity
The Franklin Township Municipal Sanitary Authority was established in 1967, and in 1970 the Authority’s wastewater treatment plant went into operation. The plant was doubled in capacity in 1985, and in 1992 it was upgraded to advanced secondary treatment. Treated wastewater is discharged into Turtle Creek, a 21-mile (34-kilometer) tributary of the Monongahela River.
Today, the Authority’s sanitary sewer conveyance and collection system includes more than 333 miles (536 kilometers) of sanitary lines, 13 sewage pump stations, and five sewage regulators. It serves the Boroughs of Delmont, Export, and Plum, the Townships of Penn and Salem, and the Municipalities of Monroe and Murrysville.
Beginning in the mid-1990s, the Authority has trucked its biosolids to a local landfill for disposal. After several years, increased demand in the service area exceeded the capacity of the plant’s biosolids treatment facility.
Solution
The Authority retained Mott MacDonald in 2000 to provide design, regulatory approval, and construction start-up services for the construction of a 750,000-gallon (2,839-cubic-meter) egg-shaped digester and associated equipment, including the following:
- Boilers and heat exchangers
- Septage receiving station with odor control system
- Sludge storage facility
- Thermally Treated Sewage Sludge (TTSS) biosolids system
- Process gas cogeneration facility
- Gas storage tank
- Waste stream screening facility
- Integrated SCADA system
Outcome
Considered an advanced wastewater treatment facility, the Authority’s treatment plant has a permitted hydraulic capacity of 4.9 million gallons per day (MGD).
The construction of the egg-shaped digester and associated equipment allowed the Authority to produce Exceptional Quality Class-A Biosolids, which can be used in agriculture and on the properties of golf courses, nurseries, and homeowners.
The project has allowed the treatment plant to meet increased demand, increased the efficiency of sludge digestion, reduced the cost of sludge handling, and reduced the amount of landfill required for sludge disposal.