Ocean City WWTP – Disinfection System Upgrades

Key Accomplishments

• Carefully sequenced shutdowns, tie-ins, testing, and commissioning so the existing chemical systems remained operational until the replacement systems were completely installed, tested, and approved for service.
• Completed demolition associated with the existing Process Building and Chemical Addition and coordinated subsequent construction of the Central Storage Building as part of the overall treatment-plant improvements.
• Performed extensive multi-trade construction involving site work, excavation, outside piping, cast-in-place concrete, masonry, structural and miscellaneous metals, roofing, building finishes, process mechanical systems, plumbing, and HVAC.
• Installed and coordinated substantial electrical improvements including distribution equipment, panelboards, branch circuits, lighting, grounding, equipment connections, disconnects, underground raceways, ductbanks, manholes, handholes, and associated electrical systems.
• Integrated instrumentation and controls for the new chemical systems, including radar chemical-level monitoring, remote indicators, level switches, containment leak detection, alarms, control wiring, and system integration.
• Managed work within an active municipal wastewater treatment facility with strict shutdown and tie-in requirements designed to minimize interference with continuous treatment operations.
• Coordinated demolition activities in portions of the existing Hypochlorite Building where preconstruction surveys identified asbestos-containing materials, lead-based paint, and other regulated materials requiring controlled handling during renovation and demolition.
• A central component of the project was the conversion from the plant's existing chlorine and sulfur dioxide gas systems to liquid chemical disinfection. The contract required the existing systems to remain operational until the new sodium hypochlorite and sodium bisulfite systems had been fully installed, tested, and accepted for operation by the Owner and Engineer. This sequencing allowed Ocean City to maintain wastewater treatment operations throughout the conversion.
• The new liquid disinfection work included installation of the sodium hypochlorite system within the Chemical Facility, the sodium bisulfite system at the Equalization Basin Pumping Station, and the associated chemical-feed piping necessary to connect the new process equipment. Construction was planned around controlled shutdowns and tie-ins, with detailed procedures required in advance and temporary connections or controls provided where necessary to maintain plant functionality.
• Process instrumentation formed an important part of the upgraded system. Instrumentation included non-contact radar level monitoring for sodium hypochlorite and sodium bisulfite storage, remote level indication and transmission, level switches, and chemical containment leak-detection systems. Equipment was designed for corrosive chemical-service environments and integrated with the plant's control system.
• The instrumentation and control work also required coordinated control-panel layouts, point-to-point wiring, automatic and manual operating sequences, interlocking, power-failure response, record drawings, and integration between equipment suppliers and the plant control system. The specifications required the completed system to function as an integrated operating system rather than as individual stand-alone components.
• Electrical improvements were extensive and included electrical distribution, panelboards, branch circuits, interior and exterior lighting, receptacles, grounding, HVAC equipment connections, transformers, disconnect switches, motor starters and relays, underground raceways and ductbanks, manholes and handholes, and electrical field acceptance testing.