Jan 05, 2021

Sea Level Rise in Virginia City Reduces Storm Water System Capacity by 50%

Rising tides have started to impact some of Norfolk, Virginia's storm water systems.

In Norfolk, Virginia, Hampton Roads’ rising tides have started to impact some of the region’s storm water systems.

According to the Virginian Pilot, when a storm begins, water will immediately start pooling around a street’s storm drain.

StormSensor, a start-up based in Seattle, placed about 25 sensors inside pipes in Norfolk. The aim is to collect data on tidal backflows into the system and measure storm drain capacities.

Based on the data, in some of Norfolk’s most flooded neighborhoods, the city’s storm water system is running at about half capacity due to sea level rise.

“Almost all the time — high tide or low tide, it does not seem to really matter — the main lines are 50% full of water,” said Kyle Spencer, a deputy resilience officer with the city of Norfolk. “When you think about managing rainfall…it’s going into a pipe that you thought was 36 inches tall, it’s only 18. We lose a ton of system capacity.”

The sensors will provide real-time alerts of when these backflow situations could become dangerous, as well as granular data that will help Norfolk optimize new flooding solutions, according to Suzie Housley, product manager and storm water scientist with StormSensor, reported the Virginian Pilot.

The sensor will focus on the effectiveness of a city’s storm water systems instead of the severity of street-level flooding. The company has placed 15 sensors in pipes near Tidewater Gardens and another 10 along St. Paul’s corridor. 

The sensors around Tidewater Garden have detected tidal water all the way from the Elizabeth River to a mile and a half inland, reported the Virginian Pilot. At several sensors closer to the river the pipe is more than 90% full of water without rain.

“That’s purely because of sea level rise and water from the Elizabeth River pushing inwards,” said Housley. “Half of that pipe that was designed to carry storm water - it’s just not available to carry storm water.”

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