Work on a $9.4 million art deco-style bridge across Interstate 5 in Ashland took a detour recently when the contractor unexpectedly uncovered rotten rebar and crumbling concrete in the old span.

Work on a $9.4 million art deco-style bridge across Interstate 5 in Ashland took a detour recently when the contractor unexpectedly uncovered rotten rebar and crumbling concrete in the old span.

The repairs, which could increase costs by more than $500,000, were not discovered in initial inspections. The new costs will be borne by taxpayer-funded transportation dollars and possibly add two months to the scheduled April completion, according to the Oregon Department of Transportation and the contractor, Concrete Enterprises of Stayton.

"Trust me, we're not happy about it either," said Rick Miller, president of Concrete Enterprises. "The concrete is a lot worse than everybody thought it would be."

ODOT inspected the concrete deck on the old span at Exit 14 in south Ashland before construction began, determining there was no serious cracking underneath or evidence of water damage that would indicate structural problems. The upper portion of the concrete deck did have potholes filled with asphalt. The 6- to 8-inch thick concrete deck is supported by girders.

Concrete Enterprises bid the job with the understanding that it could add another layer of concrete on the old span, not rip it out.

The contractor widened the old bridge on both sides of the old span. When work began last month to put another layer on the old span in the center, the company discovered the existing concrete and rebar could not be salvaged.

Instead, Concrete Enterprises is working with ODOT on a plan to rip out the old concrete deck and install new rebar and concrete.

Miller said his firm and ODOT have not settled on a price for the repairs yet, nor have they agreed on a timetable to finish the structure.

"We're still trying to figure out what do and how do it," he said.

There is enough room on the newer portions of the bridge, Miller said, for traffic to flow back and forth during the demolition, with some intermittent delays at night.

Viewed from the freeway, the new bridge appears to be taking shape, with portions of the Art Deco columns in place along with new lighting. Motorists are now driving over the newer portions of the bridge that will eventually become sidewalks, bike lanes and a part of the travel lanes.

Tim Fletcher, project manager with ODOT, said engineers who inspected the old span prior to construction made the assumption that the existing concrete deck could be rehabilitated.

In retrospect, Fletcher said, it would have been better to have removed the concrete deck at the beginning of the job.

"If we would have known then — then certainly," he said.

No core samples were taken prior to construction, Fletcher said.

ODOT is exploring different strategies with the contractor to remove the existing concrete deck without damaging the girders or the rebar that is attached directly to those girders.

One option would be to use extremely high-pressure water to blast away the concrete. Fletcher said this option would be the fastest, taking about 10 days to accomplish, but could cost more.

Another option is to use large jackhammer machinery to break up the deck. This would require chipping away by hand in some areas to ensure the underlying structure isn't damaged. This option, which would be done mainly at night, could take two to three months.

Fletcher said ODOT has been in negotiations with the contractor to determine the best option and to nail down a price for the major change order.

"It will be in excess of a half-million dollars," he said.

During the demolition of the concrete deck, ODOT could close portions of the freeway at night, routing traffic to at least one lane of traffic in each direction.

Fletcher said demolition work could start next month.

He said the increased costs are unfortunate, but the end result will be a better bridge.

He said the life expectancy of the new bike and sidewalk area would be about 50 years, but a new concrete topping on the old span probably would have required more work in about 20 years. With the old concrete deck removed, the new one should have a life expectancy of about 50 years, as well, he said.

Money for the additional work will be obtained from the Oregon Transportation Investment Act, which provides $1.3 billion for bridge repair statewide.

Of the 365 bridges funded by the program, 14 are under construction and another 256 have been completed.

A bridge at Exit 19, at the north end of Ashland, should be completed by May.

The contractor for that bridge, Oregon State Bridge Construction of Aumsville, built a whole new span, also with an art-deco theme.

Craig Gries, president of Oregon State Bridge Construction, said fencing, landscaping and lighting still need to be added.

Damian Mann is a reporter for the Mail Tribune. Reach him at 541-776-4476, or email dmann@mailtribune.com.