By The Associated Press May 08, 2010, 10:37PM The novel but risky attempt to use a 100-ton steel-and-concrete box to cover a deepwater oil well gushing toxic crude into the Gulf of Mexico was aborted Saturday, and officials said it would be at least Monday before a decision was made on what next step to take. The Associated PressA Navy photographer shoots images of an oil slick from aboard a Coast Guard plane near the rig explosion site of the Deepwater Horizon in the Gulf of Mexico Thursday.Meanwhile, there was a renewed sense of urgency as dime- to golfball-sized balls of tar began washing up on Dauphin Island, three miles off the Alabama mainland at the mouth of Mobile Bay. About a half dozen tar balls had been collected by Saturday afternoon at Dauphin Island, Coast Guard chief warrant officer Adam Wine said in Mobile. Authorities planned to test the substance but strongly suspected it came from the oil spill. In the three weeks since the Deepwater Horizon rig exploded on April 20, killing 11 workers, about 210,000 gallons of crude a day has been flowing into the Gulf. It was a troubling turn of events, especially since the intrepid efforts to use the containment box had not yet succeeded. There has been a rabid fascination with the effort to use the peaked box the size of a four-story house to place over the ruptured well. It had taken more than 12 hours to slowly lower it to the seafloor, a task that required painstaking precision to accurately position it over the well or it could damage the leaking pipe and make the problem worse. It was fraught with doubt and peril since nothing like it had been attempted at such depths with water pressure great enough to crush a submarine. It ended up encountering icy crystals, familiar territory for deepwater drilling. The icy buildup on the containment box made it too buoyant and clogged it up, BP's Doug Suttles said. Workers who had carefully lowered the massive box over the leak nearly a mile below the surface had to lift it and move it some 600 feet to the side. If it had worked, authorities had said it would reduce the flow by about 85 percent, buying a bit more time as a three-month effort to drill a relief well goes on simultaneously. Steve Rinehart, a BP spokesman in Mobile, Alabama, said late Saturday a second containment device was under construction by Wild Well Control, Inc., in Port Fourchon, Louisiana, the company that built the first one. "It's the same general idea and approach. It may be a slightly different size and shape," he said. Even as officials pondered their next move, Coast Guard Rear Adm. Mary Landry said she must continue to manage expectations of what the containment box can do. "This dome is no silver bullet to stop the leak," she said. The spot where Deepwater Horizon rig once was positioned is now teeming with vessels working on containing the well. There are 15 boats and large ships at or near the site -- some being used in an ongoing effort to drill a relief well, another with the crane that lowered the containment device to the seafloor.