Power utility Xcel Energy Inc., which provides natural gas to parts of the eastern metro area, is starting a four-year, $69 million replacement of post-World War II gas pipelines.

The lines, which stretch 11.5 miles through St. Paul and Roseville, are a key part of a system of gas mains that supply 100,000 homes and businesses, Xcel said in a statement.

The construction is designed to improve the reliability and safety of the overall pipeline by installing replacement pipe that is stronger and using welds rather than couplings to link pipe sections together. In addition, a system of remote control valves will improve pipeline efficiency and let Xcel isolate a section of pipe in an emergency. Xcel said the new pipeline also will make inspection and pressure-testing easier.

The work will be done from May to October through 2016, and some digging in streets will be required, Xcel said. This year’s portion of the pipeline replacement project will reach from Rice Street and County Road B in Roseville to Park Street and Rose Avenue in St. Paul.