Monday, September 07 2009
The U.S. Army Corps of Engineers is joining forces with the Evansville Levee Authority this week to assess the integrity of the city's 27 miles of flood protection levees and their pumping stations.
The Evansville levee system, begun after the disastrous 1937 flood, is designed to protect the city from the floodwaters of the Ohio River and is divided into seven sections.
Construction of the Knight and Howell levee — the city's first — began in 1939 and was completed in 1948. The newest section, along Pigeon Creek on the city's North Side, was added in 1994. The Federal Emergency Management Agency began calling for the certification of levee systems throughout the country in 2007 in response to levee failures at New Orleans during Hurricane Katrina
By FEMA regulations, levee systems must provide protection from an annual 1 percent flood chance, often referred to as a 100-year flood. FEMA also uses the information to formulate new flood insurance rate maps.
Jay Perry, superintendent of the Evansville Levee Authority, said monthly inspections are made to the system, but he added that the FEMA certification inspection process is much more intense and expensive.
The inspection process alone will cost the Levee Authority $408,000.
"It's a lot more thorough than our other inspections we've had, too," Perry said. "They're looking at everything from Point A to Point B and everything in between."
The 28 Corps engineers operate in teams that review the geotechnical, structural, mechanical, electrical and hydraulic aspects of the levees.
Daniel Frank, the Corps' levee safety program manager, said the inspections are just "the field scenario portion" of the accreditation process, which he expects to end Friday.
After the inspections and field reports, Frank said, the Corps will have until Nov. 12 to report to FEMA.
If Evansville's levee system fails to meet accreditation requirements, Frank said the levee authority then would have 18 months to meet the regulations before being classified as unaccredited. Such a classification could lead to FEMA deeming the area a flood zone.
"If that were the case, people who don't have to pay for flood insurance now may have to pay for it in the future," Perry said. "Hopefully, it won't come to that here. We have a few things here that aren't perfect, but that's with anything."
At the river stage of 26 feet, station pumps begin dumping rain and storm water into the Ohio River, Perry said.
"Our pumping season is from November to June. Sometimes we pump into July. This year, the river came up in August, so it really all depends on weather conditions."
The levee sections have 19 pumping stations that include 55 pumps.
Perry said small units can pump about 1,000 gallons of water per minute, and the larger units can process 143,000 gallons per minute.
In addition to paying for the inspections, Perry said, the Levee Authority will spend $100,000 to clean six miles of pipes at the pump station locations. The process must be videotaped and sent to FEMA for further assessment.