Montour school board members voted unanimously last night to borrow $17.89 million for renovations at the high school athletic center. Conceptual plans by architect Apostolou Associates Inc. show a 1,500-seat gymnasium, a swimming pool, an elevated track, locker rooms and sports offices. Interest rates on the 25-year bond issue range from 0.65 percent to 4.5 percent, about the lowest figures available over the past 30 years, financial advisor Marcia Rojcewicz, of Pittsburgh firm CIM Investment Management Inc., said.