NPU to replace natural gas mains ahead of rotary construction NORWICH -- On Monday, natural gas crews from Norwich Public Utilities (NPU) will begin replacing hundreds of feet of cast iron piping and four service lines in downtown Norwich, according to a Thursday press release. This work is part of NPU’s annual gas main replacement program. The project will take place from Main Street through Franklin Square to Bath Street, with construction taking place between 7:00 am and 4:00 pm, Monday through Friday, for one month. Traffic control will be provided by flaggers and the public is asked to use precautions when traveling through this area during working hours