As a subconsultant, SI Engineering, P.C. (SIE) provided construction management services for the North River Wastewater Treatment Plant (WWTP) Cogeneration and Electrification Project. The North River WWTP served approximately 550,000 people on the west side of Manhattan. It had a permitted capacity of 170 million gallons per day (MGD) of dry weather flow and 340 MGD of wet weather flow. It had been recommended that the electrification of the WWTP and the installation of cogeneration facilities should be pursued in order to improve the operation and the reliability of the facility, reduce greenhouse gas emissions, and provide cost effective solutions over the existing engine driven pumps and blowers.
Con Edison was required to provide four (4) new, dedicated, branch leg feeders of sufficient capacity. New electrical infrastructure provided to accommodate the new electrical supply, cogeneration equipment, and electrification of the existing pumps. The existing engine-driven Main Sewage Pumps (MSP) were fitted with electric motor drives, gearboxes, and associated equipment. The existing blower engines and associated blowers were replaced by new high-speed turbo blowers, which were installed in a new room adjacent to the engine room to provide space for the Cogeneration Engine Generator Sets and auxiliary equipment.
Additionally, a sixth MSP was installed to provide reliable pumping capacity and the required redundancy during construction, as well as additional redundancy for main sewage pumping. Digester gas systems were upgraded and included digester mixing system and digester temperature control improvements. A pressure swing absorption gas treatment system was provided for particulate, moisture, hydrogen sulfide, and siloxane removal from the gas prior to being supplied to the engines. Oxidation catalysts were installed to treat the engine emissions exhaust to meet the plant specific air emission requirements.
This project involved many contracts, so an overall contracting strategy was developed to execute the project. This contracting strategy involved pre-selection of major equipment by competitive bid. This contracting strategy was selected to reduce risk to a project and improve the schedule.
SIE provided construction management services, most specifically involving the instrumentation and controls portion, for several of these contracts. SIE’s responsibilities included inspecting the replacement of twelve (12) existing digester mixing pumps with new screw centrifugal pumps rated at 5,800 gpm and 14 ft TDH, as well as the purchasing and installation of pre-selected equipment, demolition of the existing units, installation of new units, and modification to the existing piping. SIE also assisted with the coordination of startup and testing of the new system as they pertained to the instrumentation and controls of the equipment.
