A four-mile natural gas pipeline from Pittsburg to Johnston City in Williamson County serves about 30-thousand customers of Ameren.
Thursday morning, the utility hosted an open house at its storage field in Johnston City, which stores the gas underground to prevent Ameren Illinois from running out of the energy source.

Ameren's Director of Gas Storage Steve Underwood says the open house was designed to let customers know the utility is doing what it can to keep down the cost of the gas supply.
"We're also trying to make it reliable so that in the wintertime when it gets cold and they want that hot shower and keep their house warm that we're here to serve them and keep the price as low as we can."
Vice President of Gas Operations Eric Kozak says facilities like this provide a sizable amount of energy during this time of year.
"Roughly 40% of the gas that serves our customers in the wintertime comes out of the ground from our storage fields. Almost half the gas we provide our customers throughout the winter months comes out from the ground."

Ameren's Superintendent of Gas Storage Operations Mike Kershaw says the gas is not stored in an underground tank.
"It's in a geologic formation of sandstone. The gas is kept in a microscopic pore space of that sandstone. On top of the sandstone, what contains that gas is a very hard shale and dolemite mixture that's impervious and does not allow the gas to escape."
Southern Illinois Gas Storage Supervisor Kyle Turner says there's a building on site that actually injects an odor into the gas supply. He says that's a safety feature for customers.
"So, now when they turn the gas on, if your pilot light doesn't light, you can smell that gas. Either you can remedy the situation or call somebody to fix it for you."
The Johnston City site has been storing natural gas since 1991 and serves up to 30,000 Ameren customers in the area. It is one of 12 across Ameren's coverage area.