West Pennsboro Pump Station No. 3

Johnston Construction Company

• Johnston Construction Company served as the Civil Subcontractor for the West Pennsboro Pump Station No. 3 project, supporting construction and coordination of a new municipal wastewater pumping facility in Cumberland County, Pennsylvania. The overall station incorporated a new precast wet well, packaged pumping equipment, process piping, controls, ventilation, electrical systems, standby pumping capability and remote alarm monitoring.
• The project incorporated a new precast reinforced-concrete wet well engineered for groundwater and flotation conditions. The structure was required to withstand groundwater at finished grade, incorporate watertight precast joints and pipe penetrations, access hatches, protective exterior coating and a dedicated wet-well vent with an odor-control carbon cartridge.
• The packaged wastewater pumping system utilized duplex horizontal self-priming centrifugal pumps designed specifically for raw sanitary sewage service. The specified Gorman-Rupp T4A71S-B pumps incorporated 4-inch suction and discharge connections, 15-horsepower motors, 3-inch solids-passing capability and a minimum 25-foot reprime lift.
• Each pump was designed for approximately 300 gallons per minute at 51 feet of total dynamic head, with the pumping system configured for unattended automatic operation and reliable reprime capability for sanitary-sewage service. The complete packaged system incorporated pumps, motors, valves, piping, controls and related appurtenances as a coordinated, factory-tested pumping assembly.
• The station incorporated an Allen-Bradley CompactLogix 5370 L2 PLC-based control system with digital and analog I/O, EtherNet/IP communications and operator-interface functions. The PLC provided lead/lag pump sequencing, automatic alternation, wet-well-level monitoring, pump start/stop control, alarm functions and automatic control of standby operation.