The PERC facility is located in Orrington, Maine, on a 42-acre site and consists of a number of structures designed to create a productive, efficient waste recovery process.  Construction of the Facility was completed in 1988, and commercial operations began in February, 1988.  The general contractor was General Electric Company.

Building and Unit Layout

The PERC facility consists of a number of structures including the Administration Building, Maintenance Shop Building, Rolling Stock Maintenance Building, Scale House, MSW Process Building, Switch-Gear Area and the Boiler House building.

The facility has two scales for recording truck delivery information.  The Process building serves as the delivery point and process are for the MSW.  It also has a storage area for stockpiling of the RDF.  Additionally, electrical equipment, spare parts area, maintenance area, and all associated equipment for MSW processing are within this structure.

The Boiler House area has two Riley boilers and all associated boiler and electrical equipment.  The Control Room is also located in the Boiler House.  From this Control Room, both Boiler Processes and MSW Processing are monitored.

The facility has a Safety Program administered by the on-site Safety Director.  We provide training on all required areas of safety.  The facility also performs continuing health checks throughout the year as well as industrial hygiene air sampling testing.  The plant also has its own fire safety squad.

Two Major Systems

The Facility consists of two major systems:  a front-end waste processing system and a power generation system.   The front-end system is comprised of two independent processing lines which shred the solid waste to a uniform particle size and separate the non-combustible material from the combustible portion of the waste.  Noncombustible material is further separated into ferrous metal and a residue consisting of materials such as grit and glass.  The front-end processing residue (glass and grit) is delivered to a landfill for disposal and ferrous metals are recycled.

The combustible portion of the waste, the RDF, along with wood chips from a separate woodchip processing line, is conveyed to the power generation system.  The power generation system combusts RDF, wood chips and No. 2 fuel oil in two dedicated traveling grate stoker boilers.  The RDF and wood chips are fed to the boiler using "Wolf" screw feeders.

Steam generated by the boilers drives a single steam turbine generator to generate electric power.  The turbine exhaust is condensed by cooling water in which the heat is rejected to the atmosphere by a cooling tower.  Boiler feed water is heated and deaerated with steam from the turbine extractions.  Electrical power from the turbine-generator is stepped up to 115kV and connected to Bangor Hydro's existing power transmission system through an electric substation located at the Facility.