Ameren Illinois is embarking on a 10-year $400 million overhaul of its natural gas distribution in central and southern Illinois.

The upgrade begins this summer with the replacement of 14,400 feet of steel gas line and 300 residential service lines in the central Illinois community of Chatham.

When the project is done, up to 350 miles of steel pipe will be replaced with polyethylene pipe. The project includes upgrades to 70 stations that regulate gas from interstate pipelines and adding over 450,000 so-called "smart meters."

Ameren Illinois president and CEO Richard Mark says some of the pipe is 50 years old.

The company expects to add up to 80 full-time jobs for the project.

The system upgrade began with a 2013 state law.