You’ll have to excuse Coffee County Mayor David Pennington if he gets a big smile when you mention Bonnaroo.“You can see how this has a $20 million economic impact,” Pennington said Wednesday while standing near the main stage on the sprawling Bonnaroo grounds as workers scurried around and sound checks took place.Gates opened Wednesday night at 7 p.m. and entertainment began Thursday at 4 p.m. The big acts are The Red Hot Chili Peppers, Alice Cooper, Radiohead, The Beach Boys, Kenny Rogers, and Fun.Bonnaroo has been a financial jackpot for the Midstate – and an annual celebration for music fans across America and over 30 foreign countries.“There’s no limit on who might perform here,” said co-promoter Rick Farman of Superfly Presents, noting Bonnaroo has a budget that can afford the biggest names in music. Over the years that has included Bruce Springsteen, Stevie Wonder, Metallica, Pearl Jam, Tom Petty, and Neil Young.Traffic was heavy Wednesday around noon as cars already lined the shoulder of I-24 waiting for gates to open. The Walmart across the street from Bonnaroo looked more campground than retail outlet.