From the surface, the garden could look like a row of deep-rooted native trees, maybe serviceberry, river birch or willow or a bed of pollinator flowers. Underground, their roots snake through an engineered soil that could be mixed with something like sand to become more absorbent. These rain gardens aren’t just aesthetic landscaping — they’re modern stormwater infrastructure.
Green infrastructure projects, such as rain gardens, soak up water by mimicking nature. In recent years, officials in the city of Pittsburgh and Allegheny County have been designing, building and planting new infrastructure from green ditches in between streets and sidewalks called bioswales to surface pavement that absorbs or stores rainwater right when it falls.
More of these projects are set to pop up around Pittsburgh in the next three years. The Allegheny County Health Department, along with a team of engineers from the University of Pittsburgh Mascaro Center of Sustainability Innovation and the employment and environmental nonprofit Landforce, received a $930,000 federal grant to help vulnerable communities become more resilient to the impact of climate change. The Health Department pinpoints communities in the county that have a high flood risk and have a history of disinvestment, called environmental justice communities. Pitt engineers will work with these communities to design green infrastructure projects and crews from Landforce will install and maintain them.
“This will allow the flooding [in these areas] to be mitigated,” said Melissa Bilec, co-director of the Mascaro Center for Sustainable Innovation at the University of Pittsburgh. “Things like a flooding basement may not happen as frequently or at all.”
Flooded risk
The past two decades have been the wettest on record for Pittsburgh, according to the National Weather Service. And climate predictions for the region point to a future with more rainfall and more extreme wet weather events.
With three rivers, a network of creeks, streams, aging stormwater and sewage pipes and fluvial systems coursing underground, much of the county is at risk for some degree of flooding. But some spots are more at risk than others.
Allegheny County has a series of maps that show special flood hazard areas or places where there’s a 1% chance of a flood each year, or where it could be flooded by a 100-year flood. Another map shows the county’s environmental justice communities, places like McKees Rocks, Marshall-Shadeland and Rankin. There’s a lot of overlap — 30% of the population in McKees Rocks and 71% of the population of Rankin lives in a special flood hazard area. These municipalities, along with parts of the city of Pittsburgh like Hays and Mon Valley communities like Duquesne and Clairton. are positioned on the 100-year floodplain.
“As we become a warmer and wetter area than we have in the past, we're looking to try to mitigate this through putting in green infrastructure in areas that can hold that stormwater and divert it into the correct channels,” said Thomas Guentner, director of land stewardship at Landforce. “But we are well-suited to face those challenges with a well-trained workforce.”
A sponge infrastructure
The first of these projects will take place in the Mon Valley, according to Guentner. The Pitt engineering team will work with the community to see what water-related issues they might face, like a flooded roadway and then design a system to deal with the water.
“If you have a green infrastructure project you're kind of creating a sponge, that, over time, the water will mitigate, more slowly,” Bilec said. “If it's not a green infrastructure project, you have like a glass plate. And then the water just kind of spills everywhere really quickly.”
Crews from Landforce will come in and dig the bioswale or plant the rain garden. Landforce trains and employs adults with barriers to employment to work on environmental-related projects, including these specific types of green infrastructure. They’ll also do things like pick up trash and debris, weed, prune, vacuum the spaces between pavers — all critical maintenance activities.
“One of the biggest challenges is maintenance over time,” Bilec said. “And so one of the things we see, not just with green infrastructure, but any sort of project is like — if you do not maintain it, then the effectiveness will change.”
Over the next three years, Pitt students will design six new installations and six maintenance projects for the Landforce crews to set up and maintain. Bilec says they expect to have the first project up and running by the end of this fall.
“The end goal isn't necessarily to put these green infrastructure installations in place and have them be successful,” Guentner said. “The end goal is to have those green infrastructure installations attract more funding and more attention, so that becomes a greater investment in this region.”
