"I think overall the project is on the right time frame, because the piers should be easy to build now that we found a good foundation," said Roger Wiebusch, bridge administrator for the 8th Coast Guard District in St. Louis.
Wiebusch said outside of the shift, the project's scope remains the same.
The project, estimated to cost $56 million, will move the navigation channel from a pair of 150-foot passages for barges to a single 307.5-foot passageway by changing a pivoting swing span to a wider vertical-lift span. Work will be limited to the swing span area, though a project to update the rest of the bridge is in the works.
Wiebusch was unsure whether the setback would affect the project's cost.
"The same (two) piers are going to be built, so there may be some extra work, but then there's some other stuff that might have to be done," Wiebusch said. "I don't have the exact figures as far as how it all plays out as far as the pluses and the minuses."
Wiebusch said because of the shift, one additional pier will have to be removed, but he said that work and that of constructing the new piers would not impact either navigation or rail traffic until some time late this summer.
"The work is going to be conducted such that the new ... channel pier on the east side will be built outside the navigation channel, so for the majority of the season this summer, the bridge will operate normally," Wiebusch said.
The debris was discovered early enough in the project that neither of the new piers had been constructed.
Wiebusch said once construction on the west pier starts, barges for the contractors and their equipment will block half of the channel, essentially making it a one-lane road for river traffic.
The railroad bridge project is a joint effort between BNSF and the U.S. Coast Guard as part of the 1940 Truman Hobbs Act that requires bridges to be altered if they impair the ability to navigate the river channel. The railway hired Minnesota-based Ames Construction as the main contractor, but the business has employed several local subcontractors.
BNSF spokesman Steve Forsberg said drilling for the new foundations was scheduled to be completed last month. But that was before the obstructions were discovered.
Wiebusch said the time should be able to be made up so that the project ultimately will be completed on time. The project is expected to continue into 2011.
The project long has been on the Coast Guard's to-do list. Between 1992 and 2001, the bridge was struck 92 times, making it one of three most-hit bridges in the country. Congress slowly has been building up appropriations for the 118-year-old bridge. Stimulus money helped get the project started.
According to the BNSF, roughly 30 trains cross the bridge daily. The bridge opens about 300 times a month during the navigation season to let river traffic pass.
The railroad is using the opportunity to overhaul the rest of the bridge.
"The way I characterize it, our engineering team might be out a little ahead of our finance team," BNSF assistant vice president Paul Nowicki said previously. "One group of the company is ready to go, and the other part is looking for the funding."
To complete that $120-million project, BNSF and Iowa applied for a Transportation Investment Generating Economic Recovery, or Tiger, grant. The U.S. Department of Transportation announced those recipients Wednesday, but the bridge project was not included on the short list.
Still, the railway staff is not deterred.
"BNSF greatly appreciates the consideration given to the public benefits that would have been provided by this project and for the strong leadership demonstrated by all of the public officials, business and community leaders in the state who supported the Tiger application," Forsberg wrote in an e-mail. "We're now looking at our options in terms of the fixed spans."