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Local Authorities Look to Prevent Future Flooding

This week, officials and local sewage authorities are discussing—with the public and each other—how to prevent flash flooding in Highland Park like that which took the lives of four last Friday.

Members of Pittsburgh City Council and area sewer authorities say they are taking immediate steps in the face of deadly flash flooding in Highland Park caused by a “100-year storm.”

While they indicate that sewers and roadways are not to blame for the recent deaths of four—including Plum Borough mother and her two daughters, and an Oakmont woman—officials hope to work together to keep such a tragedy from happening again.

Last Friday, in the Pittsburgh area, three inches of rain fell in one hour. Nine feet of water filled the area where Allegheny River Boulevard and Washington Boulevard meet.

Kimberly Griffith, 45, of Plum, and her two daughters, Brenna, 12, and Mikaela, 8, drowned when they became trapped in their minivan.

Mary Saflin, a 72-year-old Oakmont resident, was reported missing the evening of the flooding. The next morning, her body was found in the Allegheny River.

On Monday, the Pittsburgh Water and Sewer Authority (PWSA) met with the Allegheny County Sanitary Authority (ALCOSAN).

The two groups talked about short-term and long-term solutions, said Dan Deasey, PWSA chairman, via a statement released Tuesday by PWSA.

“We sat down to have an open discussion and share ideas,” he said.

“Very preliminary” discussions

In what the statement described as “very preliminary” discussions, PWSA and ALCOSAN considered a number of solutions that could make the area safer in the future and perhaps prevent another tragedy.

“Cooperatively determining if anything can be done in the future to mitigate problems is our focus,” said Arletta Scott Williams, executive director of ALCOSAN.  

Among measures PWSA and ALCOSAN discussed, according to the statement, were an emergency road closure procedure, a study of the Negley Run Watershed—of which the area is a part, inspection of the submerged outfall pipe by robots, street signs that would warn the public of the flood-prone area, and investigation into manhole casting and identification markers for emergency responders.

Long-term solutions include an advance warning system of flashing lights and signs, open air ponds and installation of more catch basin inlets, as well as the possibly of raising Washington Boulevard above the flood zone.

After a storm on July 18, PWSA inspected approximately 9,000 feet of sewer. The sewers were found to be in good condition, according to the PWSA statement.

Monday, PWSA televised and re-inspected its sewers on Washington Boulevard, the statement said. All catch basins were cleaned again.

"If there is something to be done, it will be done," said Nancy Barylak, ALCOSAN manager of public relations. "ALCOSAN and the other agencies are beyond devastated."

Barylak said ALCOSAN and the PWSA plan to get together again soon, perhaps in a week. The groups hope to include emergency management services, city officials and PennDOT, she said.

 An “Important Intersection”

Pittsburgh City Councilman Patrick Dowd, of District 7, might be glad to hear that. Dowd, whose precinct includes Highland Park, wanted to be present at Monday’s meeting.

“I haven’t been invited to those meetings, and I’ve asked to be invited,” he said. “Every level of government is connected to this important intersection.”

There are federal properties with the nearby lock and dam, he said, in addition to the ALCOSAN and PWSA systems.

PennDOT is involved as well, though District 11 press officer Jim Struzzi said that, in terms of the flooding, the problem wasn’t the road, but the water.

By state highway law, PennDOT is only responsible for road highway service within the city limits, he said.

That doesn’t mean the flooding doesn’t impact PennDOT.

“In 2009 we had a similar flood problem where the roadway was damaged, and a similar problem in July,” he said.

About 24,000 pass through the intersection each day, according to Struzzi. This time, the flooding did not cause significant damage to roads in the area, he said.

"We're willing to work with whoever to come up with a solution," Struzzi said. "We clearly want to see the problem solved."

The solution to the problem, according to Dowd, might be in something he never noticed before.

Walking along Washington Boulevard the day after the flood, he realized that the intersection creates a bowl, with Allegheny River Boulevard acting as a dam.

When storm water flows into the intersection, it settles, creating a lake.

“Sometimes the lake will be one inch, sometimes 10 inches, sometimes 10 feet,” he said.

There is a 15-foot drop from Allegheny River Boulevard to the lowest point of the intersection, he said.

“We need to give water a natural flow into that intersection, which means breaking that dam,” he said. “We have to find a way for it to flow naturally into the river.”

Addressing the problem of the “dam” and the water flow, he believes, could make the Highland Park intersection safer.

“We’ll all have a role and a responsibility in making that happen,” he said.

A Hundred Years Doesn’t Mean Once in a Lifetime

While the recent statement on the flooding from Pittsburgh Sewage and Water Authority described the storm as one “so severe that it’s not expected to occur more than once in a 100 years,” a hydrologist at the National Weather Service’s Pittsburgh office says that is not so.

The term “100-year flood” is a misnomer, according to hydrologist Bill Drzal.

“What it really means,” he said, “is there’s a 1-percent chance in any year of having a storm of that magnitude at a given point.”

That means it could happen again elsewhere in the Pittsburgh area.

“Just because we had it on Washington Boulevard doesn’t mean it couldn’t happen tomorrow at Girty’s Run,” he said. “The next hillside over is a new point.”

That doesn’t mean that it couldn’t happen again in the same area, either.

When rain falls in an area such as Pittsburgh, it falls on hills, gaining energy and momentum, he said. Coupled with a low point, such as the area where flooding took place, is dangerous.

“It’s going to collect in low areas,” he said.

There is no rain gage on the boulevard, Drzal said. It is reported however that three inches of rain fell in an hour during Friday night’s storm.

The sewers are designed to handle four inches of rain in a 24-hour period. Three-quarters of that total fell in an hour last Friday night.

Barylak described Friday's flooding as "man against nature." She said ALCOSAN’s system performed as it was designed to.

"Looking at that radar—and I watched it—(the storm) never moved and it gathered in intensity," she said. “That was an incredible amount of rain that fell in a short amount of time.”

See related stories on Plum-Oakmont Patch: ; ; ; ; ; ; ; ; ; .

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