HOPEWELL, Va. A Virginia woman says she experienced a once-in-a-lifetime encounter Saturday when she spotted a manatee swimming the Appomattox River near the Hopewell marina. Dawnn Thornton told CBS 6 she was waiting with her husband and a friend for the citys 250th anniversary fireworks when they noticed movement in the shallow water near the boat launch. He thought it was a huge fish, Thornton said. He comes straight up to us, and thats when w…