AUGUSTA — Summit Natural Gas of Maine and city officials have signed a contract allowing Summit to provide natural gas service to city buildings, including schools.

The contract is expected to save the city an estimated $641,464 a year over the cost of heating with oil and propane, according to city and company officials. Those savings are based on estimates the city would use $392,465 worth of natural gas a year.

City councilors voted unanimously in July to pick Summit’s bid to provide gas service to city and school buildings in Augusta. The terms and rates of the recently signed contract are based on the bid submitted by Summit and approved by councilors.

As part of the agreement, Summit is expected to invest $63 million installing 130 miles of pipeline in the city.

“The city looks forward to the economic benefits from Summit’s commitment to having natural gas available to more than 50 percent of our residents and businesses by 2015 and 90 percent by 2019,” Ralph St. Pierre, assistant city manager and finance director, said in a news release.

Competing gas firm Maine Natural Gas is also installing a natural gas pipeline system in Augusta and will serve residents and businesses. It withdrew its bid to provide gas service to the city.