BAE Systems yesterday said it received a $27 million contract to complete construction of a state-of-the-art and energy-saving chemical processing facility at the Holston Army Ammunition Plant in Tennessee.

The contract initiates the final phase of construction, which began in 2011. The total cost of the Army project will be approximately $143 million, the largest single investment at Holston.

When completed later this year, the new facility will transform and modernize the way acetic acid and acetic anhydride are produced, stored and handled at the plant for manufacturing military explosives.

“This is one of the most important projects at Holston since it opened in 1942,” said Jerry Hammonds, vice president and general manager of BAE’s Ordnance Systems, which manages and operates the plant. “The facility will significantly reduce energy usage and cut other costs, saving money for the Army and for taxpayers.”

The Holston plant is an Army-owned, contractor-operated site that produces a range of explosive fills, such as RDX and HMX, for artillery and other munitions, the company said in a statement.

Since World War II, chemicals like acetic acid and acetic anhydride have been processed at a 110-acre site located seven miles from the main plant. A rail corridor and a series of pipelines currently carry the chemicals back and forth during manufacturing. The new processing facility, in comparison, will occupy just 10 acres on the main site.

The new facility will improve operating efficiency at the plant, decrease production and maintenance costs, and reduce safety and environmental risks associated with transporting and pumping chemicals.

The facility, designed by BAE for the Army, will also utilize combined-heat-and-power technology, also called cogeneration, to produce steam from natural gas to process the chemicals. The resulting electricity will be able to power at least 90 percent of the entire plant, a major step forward in meeting Holston’s goal of energy independence.

BAE has been the operating contractor at Holston since 1999, developing innovative products such as IMX-101, which the Army approved as the first safe and effective replacement to TNT in artillery. In 2012, the company was awarded the contract to operate Radford Army Ammunition Plant in Radford, Va.