RICEVILLE — A Riceville man had pleaded not guilty to two counts of serious injury by vehicle after being accused of striking a horse-drawn buggy last month in Mitchell County. 66-year-old Ronald Mayer was traveling in the 4500 block of Walnut Avenue on February 7th when his vehicle collided with the back of a horse-drawn buggy driven by Christian Bontreger of Riceville. Bontreger suffered serious head and leg injuries and was transported to the Mayo Clinic hospitals in Rochester. Court documents state that Mayer’s blood alcohol level at the time of the accident was as high as .143, well above the legal limit of .08. Mayer filed a written plea of not guilty to the charges last week. His trial is scheduled to start on May 6th in Mitchell County District Court. Serious injury by vehicle is a Class D felony, punishable by up to five years in prison on each charge.