LocationHagerstown, Washington County, Maryland
MarketWastewater Treatment Plants
DISSOLVED AIR FLOTATION THICKENER REHABILITATION, PROCESS PIPING, SLUDGE PUMPS, STRUCTURAL MODIFICATIONS, ODOR CONTROL, HVAC, INSTRUMENTATION, SCADA INTEGRATION, TESTING AND STARTUP.
Johnston Construction Company
- Performed the major civil and process rehabilitation package for the Hagerstown Wastewater Treatment Plant Biosolids Upgrade Phase 1B, centered on replacement and modernization of the existing dissolved air flotation thickening system. JCC was authorized by Synagro-WWT to perform the GHD-designed DAFT rehabilitation under the existing Synagro/JCC subcontract arrangement.
- Delivered a DAFT system designed for continuous 24-hour-per-day, seven-day-per-week biosolids thickening. The system was designed for approximately 194,500 gallons per day of sludge feed and 19,037 pounds per day of solids, with primary and waste-activated sludge co-thickened from approximately 1.0–1.4% dry solids to approximately 4% thickened solids, with a specified 90–95% capture efficiency using chemical flotation aids.
- Removed major portions of the existing thickening infrastructure before reconstruction, including flotation-thickener equipment and piping, digester-feed pumps and pads, HVAC equipment, chillers, air-scrubber equipment and pads, building-entrance concrete, handrails, gratings, miscellaneous concrete and masonry.
- Installed the new thickened-sludge pumping and process-piping systems, including two plunger pumps designed for thickened primary and waste-activated sludge service at approximately 210 gpm and 40.6 feet total dynamic head, together with pump pads, piping, a sump beneath the dismantling joint, valves, supports and associated process connections.
- Installed and coordinated odor-control and HVAC improvements, including odor-control ductwork, supports and expansion joints, floor-drain piping, fans, heaters, louvers, motor-operated dampers, registers and associated ventilation components serving the rehabilitated DAFT area.
Electrical Services Division
- Electrical Services Division, LLC performed the major electrical trade package for the Hagerstown WWTP Biosolids Upgrade Phase 1B – DAFT Rehabilitation. ESD furnished the labor, materials, tools, equipment and supervision required for electrical construction in accordance with the project’s Division 16 specifications and electrical drawings E-001 through E-015.
- Furnished and installed the electrical power-distribution infrastructure serving the rehabilitated dissolved air flotation thickening process, including power conduit, conductors, wiring, connections, panel GP-DAFT, panel PP-DAFT, transformer GT-DAFT, switchgear, disconnect switches, boxes, devices and associated electrical equipment.
- Installed the project's instrumentation raceways, wiring and electrical connections, providing the field-side electrical infrastructure required to connect process instrumentation and control equipment with the DAFT control architecture. ESD's subcontract specifically included instrumentation conduit, wire and connections while excluding the furnishing of the instrumentation devices themselves.
- Completed motor-control and process-equipment electrical connections for the DAFT system, coordinating local control stations, motor starters and control wiring serving equipment such as the surface skimmer, bottom scraper, sludge-underflow pumping equipment and pressurization pumps. The DAFT controls exchanged equipment run status, fault alarms, start commands, speed signals and process information through the MCC and control system.
- Worked with the new MCC-DAFT power and control system, which was specified as a 480/277-volt, three-phase, four-wire, 60-Hz system with a 600-amp horizontal bus. The MCC provided motor-control and VFD interfaces serving major DAFT process equipment and incorporated remote monitoring and control functions required by the process-control system.