Fort Meade WWTP – WAS & RAS Pump Replacements

Key Accomplishments

Johnston Construction Company

• Provided two Gorman-Rupp WAS pumps rated for 150 GPM at 25 feet Total Dynamic Head.
• Provided three Gorman-Rupp RAS pumps rated for 2,300 GPM at 20 feet Total Dynamic Head, configured for alternating operation.
• JCC's internal project record further identifies the installed pumping equipment as three 10-inch Gorman-Rupp horizontal centrifugal RAS pumps and two 3-inch Gorman-Rupp horizontal centrifugal WAS pumps.
• Replaced three RAS pump check valves as part of the pumping-system improvements. JCC's project record identifies the equipment as 14-inch Milliken swing check valves with lever and weight.
• Replaced the existing RAS variable-frequency-drive system with Allen-Bradley VFD equipment, with additional VFD work associated with the WAS pumping system included in the project scope.
• Installed 480-volt, three-phase local disconnect switches for the pump equipment and completed the associated electrical work required for the upgraded WAS and RAS systems.
• Coordinated VFD installations with American Water's electrical requirements for digitally controlled, three-phase adjustable-frequency drives designed for 480V, 60 Hz service, using PWM output and motor-control functionality appropriate to the connected pumping equipment.
• Integrated the pump-drive systems with PLC-based control signals, including VFD control provisions supporting analog control from the automation system.
• Furnished and installed the required SCADA hardware, control panel equipment, cabling, wiring and associated components necessary to interface the upgraded WAS and RAS systems with the existing Industrial Control Systems SCADA platform.
• Coordinated the required SCADA programming and system integration through Industrial Controls System, Incorporated, as specifically required by American Water.
• Integrated monitoring and control of the WAS pumps, RAS pumps, valves and associated pumping-system equipment into the existing WWTP SCADA environment.
• Performed the project's associated electrical construction in accordance with American Water requirements for complete and properly operating electrical systems, including conductor testing, continuity verification, grounding, equipment coordination and final circuit activation.

Electrical Services Division

• Performed the specialized electrical and instrumentation portion of the Fort George G. Meade Wastewater Treatment Plant WAS and RAS Pump Replacement project under subcontract to Johnston Construction Company.
• Furnished the labor, materials, tools and equipment necessary for electrical modifications associated with replacement of two Waste Activated Sludge (WAS) pumps and three Return Activated Sludge (RAS) pumps.
• Removed the existing electrical connections serving the two WAS pumps and installed new 30-amp, 480V, three-phase NEMA 3R safety switches for the replacement pump equipment.
• Reconfigured existing motor-control-center equipment, including removal and relocation of an existing WAS pump starter and relocation of a 15-amp, 480V spare breaker bucket between MCC sections to accommodate the revised electrical configuration.
• Furnished and installed the conduit, conductors and fittings necessary to reconnect the existing electrical feeders to the two replacement WAS pumps.
• Furnished and installed two Allen-Bradley 5 HP PowerFlex 400 VFD systems for the WAS pumps, operating at 480V and incorporating three-contactor bypass arrangements, fused disconnecting means and line-reactor protection.
• Installed dedicated mounting provisions and associated electrical connections for the new WAS VFD equipment.
• Removed the existing electrical connections serving the three RAS pumps and installed new 30-amp, 480V, three-phase NEMA 3R safety switches for the replacement RAS equipment.
• Furnished and installed conduit, wiring and fittings necessary to reconnect the existing feeders to the three replacement RAS pumps.
• Removed the three existing RAS VFDs and furnished and installed three Allen-Bradley 20 HP PowerFlex 400 VFD systems for the replacement pumps.
• Configured the RAS VFD installations with 480V input, three-contactor bypass, fused disconnects and integral 3% line reactors, with the new units installed at the existing VFD locations.
• Performed the field electrical and instrumentation work required to connect the upgraded pump systems with the existing plant control infrastructure.
• Furnished and installed control, alarm and speed-control wiring between the existing SCADA control panel and the new WAS pump VFDs.
• Reconnected existing control, alarm and speed-control circuits from the SCADA panel to the replacement RAS pump VFDs.