A flash flood emergency is overwhelming New Orleans' complex network of pumps and other "aged" floodwater-mitigating infrastructure, according to the agency that manages it.
Roughly 4 inches of rain and exceptional rainfall rates nearing 5 inches per hour were reported at some pumping stations. The extreme rainfall rates are surpassing what the pumps can usually handle, Sewerage and Water Board of New Orleans officials told CNN.
"This means 5 inches of rain could take up to 3 hours to drain, depending on rain intensities and the ability for stormwater to quickly drain toward our pumping stations," SWBNO spokesperson Grace Birch said. "This is a significant rainfall event."
Because parts of the area are below sea level, the city has to rely on a complex pumping system to prevent severe flooding. While some drainage infrastructure relies on gravity, most are fueled by electricity-powered pumps. During heavy rainfall, the pumps can get overwhelmed to the point they can no longer remove water fast enough, causing floodwater to build.
Seven drainage pumps in New Orleans were also out of service. Two of the pumps are out of service due to routine maintenance, while the rest are either out for refurbishment or out due to issues with the electric motor, the water board said.
One of the power generators for the pumps, Turbine 4, is also unavailable, according to SWBNO.
"We have one of the most active, complex, and aged drainage systems in the world in a city that sits half below sea level," Birch said. "Our thoughts are with our surrounding neighbors in the region who are experiencing more intense rain, high winds, and tornadoes."