Sep. 3--Potentially dangerous pavement blowouts that began occurring on Midway Airport's busiest runway shortly after repairs four months ago are prompting Chicago officials to redo all of the work as a safety precaution.
Some 129 epoxy-based patches installed on Runway 31 Center in April will be replaced during an intensive 56-hour reconstruction operation next week, according to the Chicago Department of Aviation.
The runway will be shut down about 10 p.m. Sept. 10 and reopen early Sept. 13, officials said.
Airline passengers booking flights at Midway might want to avoid traveling Sept. 11 and 12, when only one airstrip that the big planes use, Runway 22 Left, will be in operation. The 31 Center repairs are being done on a Tuesday and a Wednesday, traditionally the least busy travel days.
Midway officials said passengers are not likely to experience any work-related delays, but getting in and out of Midway this summer has been more difficult than in years past.
Air-traffic delays at Midway were up 50 percent from June through August, compared with the same period in 2006, the Federal Aviation Administration reported Friday. Meanwhile, air-traffic delays at O'Hare International Airport declined 4 percent this summer compared with last summer, the FAA said.
An airport consultant working at Midway is investigating what caused some of the 129 pavement patches to fail, but officials are focusing on problems that occurred during the work in April, performed by Rossi Contractors of Northlake under a $60,000 contract.
"The primary source seems to be issues with the installation," said Erin O'Donnell, the city's managing deputy aviation commissioner at Midway. "When the patches are removed we will be able to see more."
The unusually rainy summer does not appear to be a factor, O'Donnell said.
Rossi applied an epoxy product called Delpatch in 129 locations on Runway 31 Center, which is 6,522 feet long and 150 feet wide.
A newly repaired patch of runway blew out while a jetliner took off July 19. A business plane that landed immediately after the pavement failure -- measuring four square feet and four inches deep -- sustained minor damage to its landing gear, according to the FAA.
A second pavement blowout occurred Aug. 20. City officials subsequently removed 13 additional Delpatch pavement patches based on concerns raised during maintenance inspections. Asphalt was used instead of Delpatch in the 15 locations, officials said.
Now, all of the patches will come out, and they will be replaced with more Delpatch, which city officials say is a good product used at other airports.
"It was atypical for the Delpatch that was installed in April to experience a problem so soon," O'Donnell said.
Delpatch has been used for about five years, with mixed results, at Mitchell International Airport in Milwaukee.
"Our engineers did not give Delpatch a ringing endorsement, but for the most part it has been OK for us," said Mitchell spokeswoman Pat Rowe. "How well it holds up depends on how it bonds and environmental factors."
Chicago officials said they have no cost estimate for the new work at Midway, which also will be done by Rossi under existing term agreements.
Asked whether the city would be on the hook to pay the cost, O'Donnell said, "We are investigating the accountability of the parties involved."
Rossi Construction did not return a call seeking comment Friday.
Runway 31 Center is Midway's only 100 percent concrete runway. The others -- like all the runways at O'Hare -- have a concrete base with an asphalt overlay.
Runway 31 Center, made up of about 3,000 individual concrete panels, was reconstructed in 1992 and expected to have a 20-year life span until the next major rehab, officials said.
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