Pittsburgh braces for increasingly severe flooding from climate change


Khadijah Bey did not have major flooding issues at her Homewood home. But she is worried.

Bey was hired by Grounded Strategies as a “Stormwater Ambassador” in November to learn and educate people in her neighborhood about flooding issues. That means she’s been going door-to-door in Homewood, talking with neighbors about what they’re seeing.

Many residents have flooding in their basements. A plot residents,” she said. “This just makes me wonder why so many other people have it?

His best guess: the rain is getting more intense. “It’s just not raining,” she said. “It looks like there are storms these days. There are only storms.

She’s right, according to the city of Pittsburgh’s New Stormwater Plan for New Buildings and infrastructure published in March. The average amount of precipitation per year has increased since 1840, from about 30 inches per year to an average of about 40 inches per year today.

And the worst storms got even worse. Over the past 60 years, the wettest storms have gotten about 13% wetter on average, according to the city. The wettest storms are defined as the wettest 5% of storms. Climatologists expect these storms to become more intense as the heat increases the amount of moisture in the air.

Olivier Morrison

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90.5 WESA

Khadijah Bey takes notes during a flood workshop at the Carnegie Library in Homewood hosted by the Army Corps of Engineers on May 25, 2022.

And it’s those storms that are of most concern to local water engineers, like Tom Batroney. Many roads, bridges, tunnels, pipes and buildings constructed are designed to absorb water from the heaviest rainfall. But when the rain is 13% heavier, he said, roads and buildings are flooded. And even more precipitation is predicted for the future.

If you’re installing new infrastructure, he said, “you need to be able to make sure it’s going to work not just today, but tomorrow.

So the city now says we should expect the worst storms to produce about 1.66 inches of rain. That’s a lot of water. That’s about 45,000 gallons of precipitation per acre. That’s about 5,000 gallons per acre more than what we see now. But if the trend of the past 60 years continues, Batroney said, these storms will get worse.

“You’ll never be 100% right about the future,” Batroney said. “But you take the best information you have as an engineer and try to make a decision about what that future might be.”

Protect homes and businesses

But it’s not just the city’s money that’s at stake. Residents are hurt when their homes are flooded.

“For every dollar you spend on [flood] mitigation, how much do you think it saves you? asked Andrea Carson, a community planner for the US Army Corps of Engineers during an educational workshop at the Carnegie Library in Homewood on Wednesday. After someone guessed $4, Carson said the correct answer: $6.

The Army Corps of Engineers was hold a series of workshops to educate residents about flooding and how they can protect themselves. On Wednesday, Carson spoke with a handful of residents in person and on Zoom about how to prepare their homes.

Many of the efforts she recommended are simple: Elevate your power sources and appliances in your basement, so they won’t be damaged in the event of a flood. Remove sentimental items from the basement floor. Move the boilers out of the basement. In the Chartiers Creek area, Carson said, some businesses have raised their first floors a foot or two.

Carson also told residents to remove trash and debris from the storm drains. “What happens if this storm drain is dirty? she says. “Well, it’s not going to enter the storm system as expected, but will instead pull back and come back onto your property.”

One of the tips Bey said he learned during the flood workshop was to get out when it’s raining and walk around his entire property. The idea is that she can then better see where the water is moving and how it might enter her home. It’s advice she said she would pass on to her neighbors as she continued to tell them about the floods. Bey, like many of her neighbors, she said, has two vacant lots nearby that she takes care of. And many also have abandoned houses that cause trouble.

“Either they are abandoned or people have abandoned them and the gutters are gone and the rain is just falling,” she said. “And that poses a problem for the person who still lives there.

Flood risks

Flooding isn’t just about dollars and cents, Batroney said, it’s a health hazard, especially in June and July, the months with the highest average rainfall in Pittsburgh.

Batroney said he and his wife were in Dormont in June 2018 when he saw dark clouds in the distance. Before it even started to rain, he said, “Amber, we have to get out of here. I mean, we just can’t be anywhere in this valley.

To get home, they had to take Highway 51, a road that winds along Saw Mill Run Creek.

“You don’t want to be near those major little valleys that are in Pittsburgh when it’s June and July and there’s a threat of a severe rainstorm.“, he said.You want Course. Like the name in the stream title [implies].”

Batroney’s hunch turned out to be correct. Security camera footage of a home in Bethel Park later today showed how fast flooding can happen. At 8:23 p.m. the water had just begun to rise in the driveway. And in less than five minutes, the water had reached the house. And two minutes later, the front yards all along the street had turned into a stream so high it almost completely submerged the rear wheel of the pickup truck parked in the driveway.

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Screenshot

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City of Pittsburgh Stormwater Design Handbook

Although a foot of floodwater may not seem so dangerous, according to Pittsburgh Water and Sewer Authority flood resources, that’s enough to carry an entire car. And only six inches can sweep a person. One person died in this June 2018 flood while trying to walk through the floodwaters.

Despite these growing risks, the flood workshop in Homewood on Wednesday drew only a few attendees. In 2018 and 2019, Pittsburgh had two of the three wettest years in history. But the last two years it’s rained about 40 inches – that’s a lot more than 180 years ago – but that’s about average these days. Although the amount of rain tends to increase, from year to year it can still vary considerably. And it’s impossible to know exactly how much rain will come before it does.

Although the city’s current stormwater code requires developers to prepare for an increasingly wetter future, that hasn’t always been the case. One of the reasons there’s so much flooding in Pittsburgh now, Batroney said, is because when the current infrastructure was built 50 or 100 years ago, engineers didn’t accurately predict the amount of water we would get now.

“Every bridge that crosses and every road that crosses a stream, there’s probably a pipe that could be flooded,” he said.

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