Dolly Parton is expanding — her Dollywood amusement park, that is. “I’ve always been a dreamer, so I wouldn’t describe this as a predetermined plan. It’s almost inspiration that just feels right,” the music star said Thursday in announcing plans to expand her Dollywood theme park empire in Pigeon Forge, Tenn. A $5 million, 15,000-square-foot “interactive treehouse” will greet visitors when the park re-opens in the spring. Some 300,000 people are expected to climb into the treehouse the first year. In 2001, she plans to open an adjacent waterpark, featuring water slides, raft rides and a 25,000-square-foot wave pool.