Flooding, pollution, sewage overruns region’s ‘broken’ waterways
Socks, metal poles, beer cans and baby wipes. That’s not all that washed into Southwest Pennsylvania waterways after heavy rains soaked the region this past week. Local rivers and streams likely swallowed waste from overwhelmed sewage systems and pollution from surface runoff as well.
That’s because much of the region’s infrastructure wasn’t designed with the environment in mind, said Jim Pillsbury, a hydraulic engineer with the Westmoreland Conservation District.
“In the Pittsburgh area, everyone has looked at rivers as having an industrial use,” Pillsbury said, standing near a portion of Jacks Run off Route 119 in South Greensburg.
That section of the stream, which drains a large part of the Sewickley Creek watershed, is enclosed by a concrete retaining wall. It’s surrounded by parking lots. Trees, grass and other greenery — which Pillsbury says would help protect the stream — are absent. With no shade, the water is too warm for fish to survive. Plastic bags and other debris left over from last week’s floods were caught in rocks or entangled fallen branches.
“You have all these indicators that it’s been broken,” Pillsbury said. “The stream is broken.”
A similar story exists about 35 miles west in Pittsburgh’s Frick Park, where Nine Mile Run flows through a section of the park off Braddock Avenue, said Becky Forgrave, a researcher with the University of Pittsburgh Geology and Environmental Science Department, which is researching nitrogen levels in the stream.
Nitrogen ends up in waterways from excess fertilizer in fields, storm and wastewater runoff, and fossil fuels, according to the federal Environmental Protection Agency. Though nitrogen is naturally occurring, too much of it causes algae blooms that could be toxic, killing fish or causing stomach and respiratory illnesses in humans.
After a storm, nitrogen deposits that settled across the landscape wash off into waterways, Forgrave said. Streams and rivers located near combined sewage overflow sites could experience a double-whammy when water levels rise quickly.
Forgrave pointed out a manhole cover next to the stream’s plunge pool, located just off the trail near the Braddock Avenue trail head. Baby wipes and toilet paper stuck around the outside of the cover, likely caught when the lid was pushed up by excess water running through the system just days before, she said.
“People swim in this pool because they think, ‘Oh, it’s water, it must be clean,’” Forgrave said. “But there’s a lot of sewage in there.”
Like most of the region, sewage in Pittsburgh flows through a combined sewer system. About a tenth of an inch of rain in Pittsburgh could cause combined sewer systems in some parts of the city to overflow, said James J. Stitt, manager of sustainability at Pittsburgh Water and Sewage Authority.
“It’s a single pipe that carries a combination of sanitary sewage from the homes and the stormwater sewage,” Stitt said.
During dry weather, it operates like a normal sewer system: Waste water flows out of homes, into a pipe and is carried to a treatment center. But during rainy weather, Stitt said that system, which is well over 100 years old in some places, can get overwhelmed as rain water with nowhere to go flows in. That’s when manhole covers, like the one near Nine Mile Run in Frick Park, could overflow, he said.
“It’s diluted but still contains raw sewage because the water is all mixed together at that point,” he said. PWSA monitors stormwater discharges, he said.
Steady rain over several days is manageable. But as weather patterns change, the system gets overwhelmed more frequently, Stitt said. For example, this summer has brought several intense, short-duration, high-volume storms. That water has nowhere to go as it runs over paved streets and buildings.
“That’s devastating to our system,” Stitt said.
Jamie Martines is a Tribune-Review
staff writer. You can contact Jamie at 724-850-2867, [email protected] or via Twitter @Jamie_Martines.