Wastewater Treatment Plant Headworks and Substation M Upgrade

This project is being implemented by Conceptual Design, Pilot Testing, Forebay Rehabilitation, including new high performance grit removal systems, and Improvements to Screenings Collection, Dewatering and Transport, including replacement of six-inch screens with six fine screens.  The Passaic Valley Sewerage Commission (PVSC) treatment plant is a 720+ MGD combined sewer facility and is the fifth-largest wastewater treatment plant in the United States. The headworks includes a forebay that divides the flow into channels, each of which is equipped with a screen. Additionally, it includes longitudinal grit collectors in each of the channels. PVSC experienced issues with wet weather performance, ragging in downstream processes, flooding, grit deposition and equipment requiring continuous maintenance.

The project team developed a plan to address these issues in the rehabilitated headworks facility. The plan includes an evaluation of existing systems, CFD and hydraulic analysis of the Headworks and screens, construction of a physical scale model, pilot testing of new screens with 0.50 inch openings and operational evaluation of the new screens. 

Concurrently, Greeley and Hansen has been providing design and construction services to upgrade Substation M at the treatment plant, including the replacement of the aging existing outdoor Substation M which provides 480V power to the Grit and Screening Building, Incinerator Building, Vehicle Maintenance Facility, Security Building, Administration Building and Laboratory Building. The project was on an expedited schedule in order to replace the existing Substation M as quickly as possible. Maintenance of Plant Operations (MOPO) was a critical part of this project. A phased approach was utilized so that each building had a primary and backup source of power during its transfer to the new Substation M. In addition, the coordination of concurrent projects was necessary to avoid conflicts between interfacing designs including consultant projects as well PVSC’s in-house projects. The Substation M design required careful interfacing with the new headworks, Administration Building, and feeder replacement among others. 

Project Highlights: 

• Computational Fluid Dynamics and Physical Models to test alternative design for the headworks to minimize grit deposition in the headworks forebay and to test the hydraulic flow distribution through the screening and grit channels. 
• Grit pump and sump arrangement that provides effective grit removal from the channels 
• Screenings and grit storage facility alternatives 
• Support long-term power system goals and objectives to improve plant resiliency 
• Complex project coordination to provide effective project phasing and implementation to meet MOPO requirements and coordinate with multiple concurrent projects at the plant