Even when they work properly, floodgates that warn motorists of a high-water hazard do not solve the underlying problem of chronic flooding.
Washington Boulevard in Highland Park has had this problem over the years and, after a flash storm in late August, its floodgates failed to function.
The unseen stream known as Negley Run is part of the problem, coursing inside a culvert much faster than it would if it were a stream. Storms overwhelm the culvert, which runs beneath Negley Run Boulevard and Washington Boulevard.
“The solution is to daylight that stream and get rid of that pipe and to raise [Washington Boulevard],” said John Schombert, executive director of 3 Rivers Wet Weather, a nonprofit organization devoted to addressing stormwater overflow issues.
To “daylight” the stream, engineers and landscape architects would return it to its natural habitat.
If that were the ultimate solution, how long would it take? Several less ambitious green infrastructure features have made little progress since Aug. 21, 2011, when four people died in a flash flood on Washington Boulevard.
Advocates of green infrastructure have been calling for years for green solutions to flooding and to combined sewer overflows caused by heavy rain, and green plans have resulted. But plans are about as far as it’s gone; mitigation so far has been negligible.
“The question ‘Who owns this problem?’ is fundamental to the answer,” said Deno DeCiantis, director of the Penn State Center. The center is an extension of Penn State University that works on public projects, using students in related fields.
“Does PennDOT own it because the road is too low? Does [the Pittsburgh Water and Sewer Authority] own it” because the pipes aren’t handling the volume?
PennDOT spokesman Steve Cowan said there is no plan to raise the roadway, but PWSA has a $1.3 million grant and cost-share agreement with the U.S. Army Corps of Engineers to work on a comprehensive design for green infrastructure in Negley Run, said PWSA spokesman Brendan Schubert. A request for proposals is expected to be put out by the end of this month for consulting engineers.
Daylighting Negley Run is, in fact, part of the agenda.
Mr. Schubert said daylighting the run was part of the community discussion surrounding new housing construction in East Liberty and Larimer. The new housing will have separated lines for water and sewers, making it possible to create an above-ground channel as a water feature amenity for the new Larimer Park, which is being designed now. That flow would connect to Project 15206’s green infrastructure.
“The intent is to comprehensively connect the stormwater management systems to increase [their] impact and eventually have a direct connection to the Allegheny River,” he said.
The Corps is providing 75 percent of the design funding and PWSA is providing the rest. The cost to implement the resulting design would have to be determined.
The Negley Run watershed draws from East Liberty, Point Breeze and the Lincoln-Lemington promontory on the eastern side of Washington Boulevard. Parking lots send water flying down that steep slope, but the federal government, which owns much of the land, has not responded to the Penn State Center or any other stakeholder to discuss a solution to the problem, Mr. DeCiantis said.
The only tangible results of green infrastructure so far have been water collected in 400 rain containers attached to downspouts in the 15206 ZIP code area two years ago.
If maintained and properly drained, they would keep 2 million gallons of water out of the combined sewers each year, said Matt Graham, a consultant on Project 15206, a collaboration among the Penn State Center, Pittsburgh Community Services and former-state Sen. Jim Ferlo to install green infrastructure.
Ground was broken last September on a bioswale, a phase of Project 15206, that will run along Negley Run Boulevard. A bioswale is designed to purify water through layers of plant roots and rocks for conveyance underground to the nearest natural waterway, whereas a rain garden absorbs water in place.
The plan is for it to run the length of Negley Run Boulevard and empty into a bioretention pool at the junction with Washington Boulevard.
The bioswale is designed for a peak flow of 7,000 gallons per minute. The volume of water running off the steep hillside from Highland Park per year adds another 7 million gallons to the problem, Mr. Graham said.
The curb off the north lane of Negley Run Boulevard is being reconfigured to open into the swale, and that is expected to be done in part next week, said Lisa Kunst Vavro, sustainable landscape coordinator for the Penn State Center. The bioswale is expected to be hydro-seeded in October, she said.
The delays to date have resulted from an overworked, diminished city construction division, she said, adding, ”the workers are constantly pulled off of this project for other projects.”
Mike Gable, director of Public Works, said his construction crew is on the job now to complete the swale sometime in October. The city’s investment is in manpower only, he said.
Mr. Graham’s company, Landbase Systems, designed a stormwater data and mapping service that shows rain as it falls, where it goes and how many gallons drain at each inlet. He measured 2.7 inches of rain in two hours during the storm on Aug. 28.
Lee Hendricks, a meteorologist and hydrologist at the National Weather Service, said the rain gauge in Highland Park recorded 1.58 inches between 6:30 p.m. and 7:30 p.m.
Several advocates believe the boulevard should be raised where it dips as part of the solution to flooding.
“Negley’s entire watershed is almost 6 square miles,” Mr. Graham said. “If you raised the boulevard from the bike circle area to the river, you could create capacity below the road for grass and plants. It’s the most cost-effective place to store excess water, with a green infrastructure component to take volume from the combined sewer.
“The road dips significantly for several hundred yards,” Mr. DeCiantis said. “That’s a state road, so another complicating factor. It’s complicated on the science side, complicated on the partner side and complicated on the financial side.
“You have to have a certain amount of consulting and studies, but at some point you have to start putting these [plans] in the ground.”
Diana Nelson Jones: djones@post-gazette.com.
First Published: September 18, 2016, 4:00 a.m.
