The Environmental Protection Agency has ordered two aerospace manufacturers to spend more than $21 million to clean up groundwater contamination at a Superfund site near the Hollywood Burbank Airport, the agency announced Wednesday.

New Jersey-based Honeywell International Inc. is required to spend $10 million to construct four extraction wells by 2019 and create a water treatment system. Maryland-based Lockheed Martin Corp. must also build four extraction wells by 2020 and conduct a feasibility study to determine the extent of the contamination. The total cost to Lockheed is expected to be $11 million.

The two once operated manufacturing facilities at the site that released contaminants, the EPA said.

“These important actions bring us ever closer to ensuring safe groundwater supplies for decades to come,” said EPA Pacific Southwest Regional Administrator Mike Stoker in a statement. “We will continue to work with the Los Angeles Department of Water and Power and the Los Angeles Water Quality Control Board to implement a full and thorough cleanup.”

A Superfund site is land that has been identified by the EPA as being contaminated by hazardous waste and posing a serious health or environmental risk. The 20-square-mile site located primarily in Burbank and North Hollywood was placed on the EPA’s Superfund list in 1986.

The Los Angeles Department of Water and Power draws groundwater for the city’s municipal water supply from seven wells near the site, according to the EPA. It is one of four Superfund sites in the San Fernando Valley.