OMAHA, Neb. (AP) — A series of six layoffs will reduce the workforce at the Omaha Public Power District’s Fort Calhoun nuclear plant to as few as 300 employees.

There are currently 570 employees on site. The layoffs will occur over the next 20 months as part of the decommissioning of the plant, which will permanently cease power operations Oct. 24.

The first round of cuts is scheduled around Nov. 1, and the next round is set for the first quarter of 2017.

Mary Fisher, senior director of decommissioning for Fort Calhoun, told regulators Tuesday that employees are aware that layoffs beyond 2017’s first quarter could happen sooner or later than called for in the preliminary plan.

The decommissioning process includes disassembly and decontamination of equipment, which can take decades.