Kleinfelder announced Thursday its selection by a Fortune 500 petroleum client to oversee a $125 million environmental clean-up program in New Jersey.

The San Diego-based civil engineering firm will provide soil and groundwater remediation at “a major petrochemical facility,” the company said.

Although Kleinfelder declined to identify the project site or the company for whom it will be working, there is only one such cleanup of that magnitude slated to take place in New Jersey: the remediation of more than 1,000 acres of land at refinery sites formerly owned by Exxon Mobil Corp., in the Garden State cities of Bayonne and Linden.

Kleinfelder said it will be closing multiple landfills and remediating tidally-influenced estuaries. The company wouldn’t disclose the value of its contract for the remediation work.

New Jersey’s environmental protection department sued Exxon in 2004 over pollution at the refinery sites. A state judge approved a $225 million settlement in 2015. According to media reports, Exxon agreed to pay the settlement in addition to about $260 million the firm had spent previously through 2014 as a result of a prior agreement to clean up the sites.

Kleinfelder will conduct a wide range of environmental remediation services at the site in New Jersey, including environmental engineering, environmental permitting and planning, preparation of bid specifications, contractor selection, construction management, operation and maintenance of remediation systems and regulatory reporting and negotiations, the company said.

Exxon, the world’s largest public oil and gas company by market value, ranked second on Fortune’s latest list of the top 500 U.S. companies based on revenue. The Texas-based oil giant’s profits totaled about $16 billion in 2015, roughly half that of the previous year.