Roanoke officials hope new underground sensors help control downtown flooding

By Shayne Dwyer - Reporter

ROANOKE, Va. - The stakes are high for flooding in downtown Roanoke, and the stormwater team is doing its best to make sure that doesn't happen.

Ahead of Hurricane Florence, there's a new tool helping them out.

When it rains, that water runs off the pavement downtown. It eventually makes its way underground, mixing with creeks that run right under our feet.

That's caused flooding in the past, and the stormwater team doesn't really know why, but now they're getting eyes underground.

Suction crews are out in full force working feverishly to fill their trucks up with a hurricane in the cards, and downtown Roanoke's underground storm drains need a hand full of aces.

"These are complicated things. It's not a simple process," said Dwayne D'Ardenne, the stormwater utility manager.

Multiple downtown floods made that point again and again in 2016.

The system just can't handle large amounts of rain coming down very quickly.

"This system has been cobbled together over the past 100 plus years, and we're trying to figure out how it functions in terms of hydrology," said D'Ardenne. "What comes down in the rain event doesn't necessarily flow in a direct path between here and the river."

New underground sensors went in this summer, showing us what we've never been able to see before.
They measure water depth and the flow of the marsh the city was built on top of.

"It looks like you're in the 1800s or something, and there's just a little creek running right down the middle of it. It's stream bottom there's fish swimming around in parts of it," said Marcus Aguilar, the senior stormwater research engineer. 

New rain gauges above ground work in tandem with the underground meters. That gives the city nearly 25 ways to help figure it out.

"Trying to tell a story of when it rains a lot, how much did it rain, where did it rain, and what was the response of that rainfall in our tunnel system and in our streams throughout the city," said Aguilar. 

For now, the work continues ahead of the storm.

"We're spending money to figure out how the system works to know how to spend money to fix the system the most efficient way," said D'Ardenne.

One of the biggest things to remember when we're talking about downtown flooding is not how much total rain falls, it's how long or short the storm is.

The more rain per hour, the more likely problems are going to happen. 

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