S&WB: Power failures contributed to New Orleans street flooding during latest storms (2024)

The Sewerage and Water Board said its already shaky power supply suffered a series of failures during the peak of Wednesday's torrential rains, hobbling parts of New Orleans' drainage system and contributing towidespread street flooding.

In an after-action report released Friday, the S&WB said that the downpours Wednesday morning, brought by a massive line of thunderstorms, dumped more than seven inches of rain on parts of the city. In Hollygrove and parts of New Orleans East, more than 3 inches of rain fell in an hour,far more than the S&WB's system can pump even when it is functioning at peak capacity. The system is designed to handle1 inch in the first hour and a half an inch every hour after.

But problems with its generators and one of its newer turbinesleft the utility unable to power all of its pumps as water piled up in the city's canals, culverts and streets, again exposing the vulnerabilities of an antiquated system that's regularly failed in recent years to keep New Orleans dry.

The agency, which needs 44megawatts of electricity during peak timesto keep the system fully up and running, has struggled to produce that muchsince at least February, when one of its main sources of power, known as Turbine 4, was knocked out of service.

And officials operating the already impaired system confronted several major challenges on Wednesday that forced the utility to ration power to pump stations during the storm.

Problems mount

According to the report, the first issues became apparent to S&WB workers around 9 a.m. Wednesday, when the utility attempted to use its three working generators to send power to one of its major pumping stations, Station 6, which sits in the 17th Street Canal.

All three generators tripped offline, and the S&WB later determined the cause was an issue with the electrical feeder that runs from the generators, housed at the Carrollton Water Plant, to the pumping station. According to a statement from the S&WB that accompanied the formal report, the New Orleans Police Department is currently investigating the issue as a case of potential vandalism.

The utility confronted a second major issue at about the same time, when it attempted to send power from anotherof its turbines — Turbine 6 —to Pump Station 6 as well as a series of stations along Broad Street.

Because that turbine is relatively new, installed after Hurricane Katrina, the power it produces needs to be converted by a frequency changer for use by the older pumps.

But the frequency changer tripped offline, rendering that power source useless,too.

The utility finally began using Entergy power to bring the frequency changers back online, allowing the pumping stations to begin using power from the changers between 10:15 a.m. and 11:25 a.m.

Without all of the necessary power, the Sewerage & Water Board was forced to leave some pumps off during the storm.

Too much rain

The S&WB reported an average rainfall of 6.23 inchesduring the storm Wednesday, nearly 2 inches more than during the last major storm that flooded many parts of the city on Feb. 3.

That intensity of rainfall meant that even areas where pumps were working properly saw street flooding. For instance, the S&WB said its 27 pumps used for underpasses were all available during the storms, but multiple underpasses were still flooded because the pumps couldn't keep up.

"Considering the power issues facing us, our drainage system and operators fared well during the April 10 rain event," S&WB officials wrote.

That's likely to provide little solace, however, to business owners frustrated by frequent flooding and residents dealing with swamped cars. The issues Wednesday may prompt more action in Baton Rouge, where legislators are currently debating reforms to the S&WB.

Mayor LaToya Cantrell has not commented on the flooding emergency in New Orleans or the S&WB report.

Questions remain about the specific cause for the generator and frequency changer malfunctions. Both are under investigation, according to the report. A spokesperson with the S&WB declined to provide additional details about the possible vandalism.

The electrical feeder was repaired on Thursday, returning the three back-up generators to service, the S&WB said, while noting that the real fix is the large-scale power stationslated to come online by the peak of hurricane season in 2025.