<p><br /> BP has been dealt a setback to capping a massive oil spill in the Gulf of Mexico after a containment dome encountered flammable formations as it was lowered onto the leak site.<br /> </p><p><br /> The gas hydrates, similar to ice crystals, formed on the inside of the 100-ton chamber as it neared the seabed nearly a mile below the surface, making it too buoyant and clogging it up.<br /> </p><p><br /> Workers have moved the concrete and steel box some 650 feet to the side on the seabed while they evaluate their options.<br /> </p><p><br /> An estimated 210,000 gallons of oil have been gushing every day from a pipe ruptured when the BP-leased Deepwater Horizon sank on April 22, two days after an explosion that killed 11 workers.<br /> </p><p><br /> The high-stakes attempt to cap the leak, rife with expectations because it will take three months to drill relief wells to stem the flow, had been considered the best short-term solution to stave off the biggest US environmental disaster since the 1989 Exxon Valdez spill in Alaska.<br /> </p>
