A city of water: Experts explain how climate change impacts Pittsburgh’s infrastructure

Aug 9, 2021

As the climate crisis hastens, many experts believe Pittsburgh — at the center of the Rust Belt — will be a part of something new: the “waterbelt.”

In Washington, D.C., this week, lawmakers are set to pass a $1 trillion infrastructure deal that includes billions to prepare for the effects of climate change, such as flood control, river dredging, highway relocation and more. It would be the largest investment in climate resilience in the nation’s history. And it would be timely, as the United Nations on Monday released its own report calling climate change a “code red for humanity.”

At the top of many experts’ lists on how climate change affects Pittsburgh is flooding. They echoed that more precipitation because of climate change leads to more extreme floods — a challenge for the region’s aging stormwater management system.

David Dzombak, a professor and the head of civil and environmental engineering at Carnegie Mellon University, studies the effects of regional climate change. In 2019, he published climate histories for more than 100 U.S. cities in the Journal of Climate that showed that climate change’s global trends are well defined — higher temperatures, rising sea levels and more extreme weather events — but its impact on individual cities is more nuanced.

“In general, dry places are getting drier and hotter, and wetter places are getting wetter,” Mr. Dzombak said. “In Pittsburgh, we get pretty uniform precipitation over the course of the year. But the amount of precipitation has been going up here a bit, and what is also changing is the extremes. There have always been occasional extreme storms here with very intense rain or very intense winds, but it’s the frequency with which those occur. That’s changing.”

The intensity of recent summer storms in the city isn’t a coincidence, Mr. Dzombak said, citing an example. At his Oakland office in mid-July, he witnessed a heavy storm that lasted 10 to 15 minutes and dropped around an inch of rain.

“The system was overwhelmed and the effect occurs on a broad basis,” he said. “You can get really widespread flooding as we’ve seen.”

In 2018, Pittsburgh experienced its wettest year on record with 57.83 inches of precipitation. As of June, 2021 has seen slightly more than 19 inches of precipitation, according to the National Weather Service. The weather trend is why some scientists are referring to the mid-Atlantic and upper Midwest regions of the U.S. as the “waterbelt,” Mr. Dzombak said.

The problem, experts say, is that Pittsburgh’s current stormwater infrastructure — grates, gutters and pipes — isn’t equipped to handle the heightened level of precipitation. Pittsburgh has a combined sewer system, meaning wastewater and stormwater is sent through one pipe to the Allegheny County Sanitary Authority.

The system was revolutionary when it was built in the 19th century, but today the Pittsburgh Water and Sewer Authority acknowledges on its website that putting wastewater and stormwater through one pipe is “no longer acceptable,” because sewage overflows into rivers, streets and basements. This leads to property damage as well as severe health risks, which disproportionately affect Pittsburgh’s low-income and predominantly Black neighborhoods.

“What’s happening with climate change is ... more rainfall means more combined sewer overflow. What also happens is those bigger storms are more likely to produce these big overflows,” said Jordan Fischbach, the director of planning and policy research at the Water Institute of the Gulf, who has extensively studied Pittsburgh’s stormwater system.

Pittsburgh and PWSA are working to address this problem. The city announced in late July that the state awarded PWSA an almost $24 million loan for wastewater infrastructure repairs, although that’s considered a fraction of what’s needed at Alcosan. But Mr. Fischbach said overhauling the system is complex, costly, and, because of climate change, changing over time.

Heavy rainfall also leaves the Pittsburgh region at a higher risk of landslides, he noted. He said landslides can “block roads, damage infrastructure, cause outages for periods of time, and lead to increased expenses for road maintenance.”

But while the risk of flooding is high, the scientists also stressed that water will make Pittsburgh a more sustainable place to live as the effects of climate change, particularly droughts and wildfires, become more prevalent nationwide. Read the full story here.