Project Profile: Northwest Suburban Municipal Joint Action Water Agency Backup Generator Project

Engineering firm: CDM Smith Inc.
2022 MEP Giants rank: 50
Project: Northwest Suburban Municipal Joint Action Water Agency Backup Generator Project
Location: Chicago, IL, United States
Building type: Utilities/public works/transportation
Project type: New construction
Engineering services: Automation, controls; electrical, power; HVAC, mechanical; lighting; plumbing, piping
Project timeline: January 2019 to December 2021
MEP/FP engineering budget: $485,000

Challenges

There were several challenges on this project, including the coordination of the pre-procurement of the diesel engine generators and paralleling switchgear, the conduit routing on-site and through the existing pumping station, and the modifications to the existing main switchgear.

Two 2000kW, 4.16kV diesel engine generators and associated day tanks. Courtesy: CDM Smith

Solutions

Conduit Routing – The most challenging component was the conduit routing on-site and through the existing pumping station. There were several buried utilities and vaults on-site, and the existing electrical room was a slab on grade. Several options for the routing were evaluated, including through the existing pump room and along the roof, but both were met with additional challenges and obstructions. The approach designed was to excavate the floor and under a wall of a storage room and stub up the conduits into the garage. From there, the conduits were routed overhead above a drop ceiling and into the electrical room. Some equipment located above the drop ceilings had to be relocated to make room for these conduits.

Pre-Procurement – CDM Smith coordinated with CAT on the pre-procured paralleling switchgear to ensure that the conduit and wiring required for the interconnections between the new switchgear and the other system components were covered in the design package and that the delivery of the new generators and switchgear would be coordinated with the construction schedule for the installation contractor.

Existing switchgear modifications – The existing 4.16kV main switchgear was constructed in the mid-1980s and included electromechanical relays. New SEL relays were designed for the existing circuit breakers, and the circuit breaker controls had to be revised so that they could be controlled by the new generator control system. New compartment doors were designed for the new protective relays, test switches, and control devices which detailed the layout for the doors. There were also modifications required to the switchgear control wiring, and this work was detailed in the design package by showing the necessary modification on the existing switchgear three line diagram and circuit breaker control schematics.

New Electrical Room and Paralleling Switchgear. Courtesy: CDM Smith

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