SWBNO: Operator error not to blame for June 10 flooding

SWB

The Sewerage and Water Board of New Orleans released its “after-action” report outlining what led to last Wednesday’s street flooding in New Orleans.

The SWBNO says through an investigation of operation logbooks, the utility found ‘no evidence’ the flooding was caused by pump operator error.

Instead the report blames the aging turbines, pumps and the complexity of the drainage system for the flooding on June 10.

“No one predicted that more than 3 inches of rain would fall in little more than an hour that morning,” said SWBNO Executive Director Ghassan Korban. “But our team responded well. They did – and continue to do – a tremendous job operating a drainage system that still runs practically the same way it did a hundred years ago.”

The SWBNO report says:

About 3 inches of rain had fallen at Drainage Pump Station 2 on Broad Street in Mid-City between 6:40 and 7:45 a.m. The National Weather Service issued a flash flood warning at 7:51 a.m., but by then the flooding had already begun.
As the rain began, SWBNO had T4 and its Entergy frequency changers in service. By 7:10 a.m., T4 was producing more than 10 megawatts (MW) of power. The operations team started Turbine 1 (T1) and began to move pumps from T4 to T1 when a safety mechanism tripped and T4 shut down. That safety feature protected the turbine from damage. At no time did the operators overload T4 beyond SWBNO’s internal limit for that machine of 18 MW.
The rain event timeline, supported by photos from the Real-Time Crime Center cameras, shows the floodwaters had reached their top height before T4 tripped offline. The power loss delayed SWBNO’s ability to drain the city, but it did not exacerbate the flooding that had already occurred.

The SWBNO says it will take a number of steps in mitigating future flooding, including starting turbines and generators sooner and moving to a ‘higher alert’ for storms predicted to be less severe.

The utility also says the drainage system will not have its full 20 mega-watt power capacity for this year’s hurricane season since turbine 5 exploded back in December.