COLUMBIA, S.C. (AP) — The chief contractor at a failed multibillion-dollar project to build two nuclear reactors in South Carolina has agreed to pay more than $20 million as part of a cooperation agreement with federal authorities probing the fiasco.

Under an agreement announced Monday by Acting U.S. Attorney Rhett DeHart, Westinghouse Electric Co. will contribute $5 million to a program intended to assist low-income ratepayers affected by the project’s failure. Another payment of $16.25 million will be due before July 1, 2022.

The company will also be required to cooperate with federal investigators still probing the company's role in the 2017 debacle, which cost ratepayers and investors billions and left nearly 6,000 people jobless.

Westinghouse was the lead contractor on the construction of two new reactors at the V.C. Summer plant. South Carolina Electric & Gas Co. parent company SCANA Corp. and state-owned utility company Santee Cooper spent nearly $10 billion on the project before halting construction in 2017 following Westinghouse’s bankruptcy.

The collapse of the V.C. Summer project spawned multiple lawsuits, some by ratepayers who said company executives knew the project was doomed and misled consumers and regulators as they petitioned for a series of rate hikes. Three top-level executives have already pleaded guilty in the multi-year federal fraud investigation. A fourth has been charged and is expected in federal court Tuesday.

On Monday, DeHart said Westinghouse has given federal investigators more than three million pages of documents, data and correspondences and made employee witnesses available for interviews. Through its former parent company Toshiba, Westinghouse has also made more than $2 billion in settlement payments related to the project.

Since the failure, Westinghouse has removed, reassigned or retrained its senior management, elected a new board and implemented new financial controls, according to DeHart.