Over the years, as Pittsburgh’s urban landscape has expanded, roads, buildings and parking lots have taken over natural, rain-absorbing green spaces, creating streambeds of concrete and asphalt that channel stormwater and debris into our overburdened sewer systems. As a result, it takes only one-tenth of an inch of rainfall to flood our sewer system and send stormwater and raw sewage pouring into our rivers.
Under federal orders, the Allegheny County Sanitary Authority came up with a $2 billion plan to address this problem almost exclusively with “gray infrastructure” — pipes, reservoirs and the like. But Alcosan is beginning to change course and EPA guidelines increasingly require municipalities to include natural solutions or “green infrastructure” in stormwater management plans.
In recent years, we have seen many notable independent projects incorporate green infrastructure to mitigate or eliminate stormwater runoff. But to address stormwater overflows on a scale significant enough to make a notable impact on our region, and to do so in a way that produces quantifiable results, is a complex task requiring a public-private partnership among multiple entities — those that own the land, those that own the pipes, those that develop and fund the projects, and those that promulgate the regulations — as well as monitoring procedures to document the effectiveness of the green technologies used.
Measuring the effectiveness of a gray infrastructure system such as a pipe is straightforward; documenting the efficacy of engineered natural systems such as irrigation trenches, porous pathways or tree installations is more complicated, but it is possible.
In 2012, a total of 82.6 million gallons of water poured into Schenley Park’s Panther Hollow Lake from the surrounding watershed and then into the city sewer system. This water contributes to the discharge of sewage into the Monongahela River when it rains.
In an outstanding example of community collaboration, the Pittsburgh Parks Conservancy, the city of Pittsburgh, Alcosan, the Pittsburgh Water and Sewer Authority and others created and are in the process of implementing a comprehensive, monitored stormwater management plan to reduce these overflows. The aim is to restore the 300-acre watershed in Squirrel Hill, Oakland and Schenley Park that feeds Panther Hollow Lake.
The project’s green infrastructure elements include the placement of infiltration trenches along Beacon Street to capture and redistribute stormwater to newly planted woodland meadows and the installation of a new lawn and wildflower meadow at the Bartlett Street Playground to capture and soak up rainwater. At the Schenley Golf Course, operated by First Tee, portions of the lawn are being re-graded to include humped swales, moisture-retentive soils and new trees, bushes and grasses. These initiatives are expected to capture 1.7 million gallons of stormwater per year.
Another phase of the project will reshape Schenley Drive, reducing the amount of impervious asphalt and including the installation of infiltration berms and a porous, rain-absorbing pathway for bikers and pedestrians. These efforts are expected to reduce runoff by more than 3.3 million gallons annually.
They also will preserve the historic landscape design of Schenley Park. Stormwater management can be a valuable preservation strategy by restoring groundwater and stream systems. Our large regional parks, for instance, have been systematically starved for water over the last century because the gray infrastructure system has been diverting rain water into pipes.
Perhaps most significantly, this work in Panther Hollow has been designed to include monitoring that can determine its effectiveness. Over time, project research partners at the University of Pittsburgh, led by assistant professor Dan Bain, will be able to see and verify the response in soil moisture, groundwater, stream flow and the amount of water draining out of the lake.
The work being done in Panther Hollow is a model for what can be accomplished countywide and beyond.
Our region is home to more than 29,000 acres of city and county public park lands that even in their current state act as a natural sponge in capturing rain water and cleaning particulates from our air. But our region’s parks also have the potential to mitigate many more millions of gallons of stormwater overflows through the installation of green infrastructure and improvements that restore natural habitat and ecological balance.
Numerous changes can be made in our parks to capture and absorb rain where it hits the ground. These include replacing compacted, water-repelling short-grass lawns with thirstier grass varieties, planting different types of trees and bushes, restoring forested areas and reducing unneeded expanses of pavement, all while enhancing the parks.
In doing so, we not only can address our stormwater issues, we also can improve our air and water quality and start to view and use rainwater as the resource that it is.
Meg Cheever is president and CEO of Pittsburgh Parks Conservancy (www.pittsburghparks.org).