NEW ORLEANS — Saturday morning, as up to seven inches of rain swamped the city, the New Orleans Sewerage and Water Board struggled to cobble together enough electricity, through a complicated mix of sources, to power drainage pumps to keep the streets from flooding.
During the storm, Turbine 4, which is a key supplier of 25 hertz power to many of the pumps, tripped offline. Turbine 5 had been out of service since late October due to mechanical problems.
That left the SWBNO with about half the power it needs during peak demand to run the pumps. According to the water board’s after-action report, there was a long list of problems hindering the utility’s power generation ability prior to the rain event.
Turbine 4 was only running at half of its 20-megawatt capacity to allow for maintenance of boiler room fans before it eventually clicked offline.
Two of the five EMD generators that serve as backups to the turbines were out for repairs. The three that were available would not start, according to the report. They finally started about an hour after the rain stopped.
Two of six frequency changers needed to transform power from the electrical grid for use by the city’s ancient drainage pumps also went down.
When Turbine 4 failed, it knocked out pumps in Lakeview and Mid-City. It also caused other pumping stations to run at reduced capacity. What followed was widespread street flooding across the city.
The SWBNO now hopes to bring T5 back online by December 15.
T4 is expected to be out until further notice.
The long-term fix is a new power substation now being built at the water board’s main plant in the Carrollton neighborhood. It is now expected to replace the turbines as the utility’s main source of power by peak hurricane season in 2025.