Protecting to Serve
To ensure the facility wouldn’t fail under another flood, we were tasked with fully protecting the entire plant’s electrical supply and distribution system from a 500-year flood event in addition to replacing the original, deteriorating switchgear. To replace the plant’s 4,160-volt main switchgear and at the same time keep the facility operational required the installation of a new electrical building on the site.
Rising Above
We designed the two-story electrical building to stand 2 feet above the 500-year flood elevation. The first floor houses four upgraded diesel generators relocated from the existing electrical building, one new generator and space for a future generator. The upgraded switchgear and variable frequency drives (VFDs) are situated on the second floor. In addition to being flood-resistant, the structural steel building was designed to be earthquake-resilient to meet stringent International Building Code requirements.
Built-in Backup
To increase reliability, we designed redundancy into the various electrical systems. The upgraded diesel generators transferred from the existing electrical building can produce enough power to operate the entire plant at the rated 90-MGD capacity, providing a standby electrical power source for the entire plant. We increased energy efficiency by installing 4160-volt VFDs on the high service pumps to vary treatment system flow rates to match the water distribution system demands.
Never Missing a Beat!
Gresham Smith engineers replaced K.R. Harrington’s entire electrical system—from switchgear and cables to instrumentation and controls—without shutting the plant down. As a result of the complex project, the Nashville metropolitan area and its surrounding communities now have a more weatherproof 90-MGD water treatment plant.