Aging storm sewers no match against flash flooding; high costs make fixes prohibitive
Pittsburgh's $150 million stormwater management plan will debut next week, but better storm sewers couldn't prevent the flash flooding that occurs more and more frequently in Western Pennsylvania, wet weather experts said.
Drenching rain this month happened so quickly and with such fury that no system of dikes and pipes could handle it, said Nancy Barylak, spokeswoman for the Allegheny County Sanitary Authority, which serves 320,000 commercial and residential customers in 83 communities.
“You can never build a system to handle floodwaters,” Barylak said.
The crux is hilly topography and storms that dump a large volume of water in a short period. A week after flash floods hit Dunbar Township in Fayette County, stormwater systems on July 10 were overwhelmed when typically docile streams overflowed onto streets and into homes and businesses in the South Hills, Oakdale, Bridgeville and communities north of Pittsburgh.
Heavy rain caused flooding again during the past two weeks, swamping communities such as Elizabeth Township and Glassport several times.
“The biggest problem we have right now, as I see it, is these short-term events where streets become flooded and dangerous,” said Pittsburgh Public Safety Director Mike Huss. “What we had was an immediate life-threatening event on Route 51.”
The city closed Route 51 running through Overbrook and other South Hills neighborhoods for most of that day when Saw Mill Run flooded the road and businesses. Swiftwater rescue teams pulled seven people from water that was surging down Route 51 and Banksville Road.
Flooding from longer-lasting storms such as Hurricane Ivan in 2004 is more predictable and provides people time to move personal property, said John W. Schombert, executive director of 3 Rivers Wet Weather, a nonprofit started in 1998 to help Allegheny County municipalities alleviate stormwater overflows into waterways.
When the remnants of Ivan approached, James Andeits said he had time to rescue his inventory of used cars from A-1 Auto Mart on Saw Mill Run Boulevard before it flooded. This July was much different.
“It's the fastest water I've ever seen,” said Andeits, who has sold cars at the lot since 1999. “Ivan, the water was deeper but not as fast.”
The water rose so fast that Andeits could save only five or six cars. Floodwater soaked the interiors of 26 others, causing $140,000 in damage, Andeits estimated. He has insurance, but he also has had it with floods.
“I can't take it anymore,” he said. “I want to move.”
Bigger communities, bigger threat
Flash flooding happens when water runs off hard surfaces such as roofs, concrete and asphalt, experts said. As communities grow, so does the threat.
“As long as we keep adding more impervious surface for the water to run off on, we're going to keep having problems on the ground,” said Brenda Smith, executive director of Nine Mile Run Watershed Association, which advocates green solutions to stormwater problems. “Now every time we have a big rainstorm, there's flooding somewhere, and it's usually in multiple locations.”
Governments and organizations have taken steps to alleviate the problem, but cash-strapped municipalities such as Pittsburgh and Oakdale can ill-afford the cost.
“We're very limited in what we can do and decisions we can make as individual municipalities when it comes to the creeks,” Oakdale Mayor Paul Hennemuth said.
Municipalities across the country are under federal mandate to drastically reduce stormwater that overwhelms sanitary sewers and runs into waterways during heavy rain. They must submit reduction plans to federal and state regulatory agencies this year.
The Pittsburgh Water and Sewer Authority's plan preliminarily includes building miles of larger pipes, a large holding tank in Highland Park, separate lines for stormwater and sewage, and green infrastructure.
Jim Good, interim executive director of PWSA, which has about 300,000 customers in the city and neighboring communities, said the authority routinely upgrades stormwater infrastructure when it repairs sewer lines. Jeff Karr, assistant district executive for maintenance for PennDOT District 11, said his agency does the same thing with drainage infrastructure on large highway projects.
Yet it isn't enough, they said.
“There could be a storm tomorrow that's bigger than anything you or I have ever seen, and it can completely overwhelm the system,” Good said.
Progress comes at a price. In the aftermath of Hurricane Ivan and subsequent storms, the Army Corps of Engineers' Pittsburgh District spent $21 million to improve flood management systems, said T.J. Fichera, the district's emergency management chief.
The Corps dredged creeks, straightened and smoothed streams, widened culverts, and repaired bridges, floodwalls and levees. It spent $500,000 to remove sediment from Campbells Run in Carnegie.
“Since Ivan, I have not seen a flood event in Millvale, Etna, Thompson Creek, Jeannette,” Fichera said. “Those are locations where we've invested money and see the benefit.”
Etna spent about $2 million on flood control projects after Ivan, said Mary Ellen Ramage, the borough's manager. Crews drove large poles into Parker Street Run to catch debris before it floats downstream and piles up at bridges. They stabilized stream banks.
The borough borrowed $500,000 after Ivan to upgrade sewer lines. Shaler and other communities upstream installed debris catches and pools.
“There's always good that comes out of bad,” Ramage said.
But federal and state money for flood control dried up in recent years.
The Corps started no flood-management projects in the aftermath of Ivan and has no plan for projects to address this year's flooding. The climbing price tag of flood management projects — often millions of dollars — prevents many from starting, said John Peukert, plans and environmental chief for the Corps in Pittsburgh.
The Clean Rivers Campaign, a coalition of environmental groups that includes Nine Mile Run Watershed Association, thinks the answer is low-cost remedies such as rain barrels, rain gardens, tree planting and porous pavement.
Allegheny County late last year began discussing a countywide plan that would require developers to manage stormwater on their properties, said Bob Hurley, senior deputy director of Economic Development. If approved, it would provide a model stormwater management plan for the county's 130 municipalities.
“We will encourage municipalities to either adopt it or incorporate it into their own ordinance,” Hurley said.