No major-league baseball has been played at Candlestick Park in San Francisco since 1999, but since the Giants called it home for 40 seasons (1960-1999), this story has a baseball-related, um, impact: Plans are to blow up the 69,OOO-seat stadium with a 3O-second implosion, possibly within weeks of the 49ers' final touchdown next season. San Francisco's Recreation and Park Department, which owns Candlestick, had feared it would be stuck spending millions to mothball the 53-year-old structure until Lennar Corp. was ready to build something on the land. Lennar, however, figures there's no point in waiting. "The best thing for our development and the neighborhood is not to have that hulking building sitting there empty," said Kofi Bonner, president of Lennar Urban, which plans a retail, residential and office complex for the stadium site and the former Hunters Point Shipyard.