Chicago Flooding May Linger for Days : Repairs: Crews begin work on giant plug in an effort to stem the underground deluge. One estimate says damage could top $1 billion.

Waterlogged residents may have to wait days until a labyrinthine underground tunnel system that flooded the city’s downtown is drained, Mayor Richard M. Daley said Friday.

The Chicagoland Chamber of Commerce said the price tag for the disaster in terms of lost business, productivity and other costs could top $1 billion.

Daley refused to guess how many days it would take to block off the damaged part of the system. Gen. Russell Fuhrman of the U.S. Army Corps of Engineers on Thursday said it could be 15 days before the tunnel system is drained.

“I don’t want to create false expectations,” Daley said. “It will be some time before commerce in the Loop will be back to normal.”

Officials said they were making slow progress on delicate efforts to repair the old freight tunnel under the Chicago River.

It ruptured Monday, sending millions of gallons of river water pouring through the tunnel system and into downtown basements, hobbling the nation’s third-largest city. Power was turned off to more than 200 buildings.

The first stages of a giant concrete plug were poured Friday in a bid to stop the underground flood.

Shafts were sunk on each side of the river from street level down through the tunnel roof, and workers began pouring quick-set concrete down one of the shafts. The concrete hardens on hitting water still in the tunnel and will eventually form a 20-foot-long floor-to-ceiling plug in the section being filled in.

Bob Wysocki, spokesman for the city Department of Streets and Sanitation, said a similar operation would begin on the other side of the river if the plug being formed Friday holds.

About 35 buildings still had water in their basements or subbasements, with levels ranging from one inch to more than 30 feet, according to Fire Commissioner Ray Orozco.

City Hall still had water in its subbasements Friday and was closed to the public.

Power to all but 11 buildings has been restored. The Chicago Board of Trade had full power restored but was closed for trading for the holiday weekend. The Art Institute of Chicago, which usually closes just one day a year, Christmas, was back in business after being cut off earlier in the week.

Those still out included the flagship stores of two major retailers, Marshall Field and Carson Pirie Scott & Co.

Officials of both stores said they will lose millions of dollars but will ultimately recover.

But owners of smaller stores and restaurants were not so optimistic.

“It’s a disaster,” said Angelo Lampus, owner of the Around The Clock restaurant. He says he has lost $20,000--$12,000 worth of food and $8,000 in business--since the flood closed his restaurant Monday.

Stores that could reopen reported that shoppers stayed away. The State Street Mall, usually bustling with customers, was nearly deserted Thursday afternoon and during the evening rush hour.

Business owners standing in empty stores blamed a ban on downtown parking and the closure of two subway lines.

Some business owners said they do not have insurance to cover their flood losses and are not sure if they would qualify for federal assistance, although President Bush issued a disaster declaration Wednesday.

But officials for Field’s and Carson’s said both stores have insurance covering building and merchandise damage, as well as for business lost during a disaster.

Neither store expected to reopen before next week.