Explosives leveled what was once the world's tallest smokestack, the most visible part of cleanup after a century of pollution from a copper smelter in Ruston. The 562-foot landmark was demolished without a hitch before thousands of cheering onlookers. Made of 2 1/2 million bricks, the stack crumpled and sank into a pit the size of two football fields. Controlled Demolition International used less than 400 pounds of nitroglycerin-based explosives to bring it down, said Doug Loizeaux, CDI vice president. "That's a lot of bang for your buck," Loizeaux said. The stack once vented sulfur dioxide and other fumes. The smelter was declared a federal Superfund site because of arsenic and lead contamination.