Deepwater Horizon drilling rig, prior to the explosion.

BP announced Friday that the relief well has been completed. If everything goes according to plans, the oil well that sparked the worst environmental disaster in U.S. history will be permanently sealed on Saturday.

The well in the Gulf of Mexico hasn’t leaked oil since the company stopped it on July 15. But to date, it has not been permanently sealed off. The one remaining step is a procedure call a ‘bottom kill’, which is done by pouring cement into the bottom of the well. According to officials from the company, this will take place on Saturday.

Thad Allen, the incident commander for the disaster, announced that officials had determined that the relief well had in fact intersected with the Macondo well. The intersection of the wells is approximately 18,000 feet underwater in the Gulf.

After the Deepwater Horizon rig exploded on April 20, an estimated 206 million gallons of oil poured into the Gulf of Mexico. On July 15, a cement plug was installed in a procedure called a ‘static kill’, which stopped the leak.

The cause of the explosion, in which 11 men were killed, is still under investigation. BP’s internal investigation blamed a variety of human error and sub-standard materials used in the construction of the well. A critical piece of evidence in the investigation is the blowout preventer, which many say should have stopped the explosion from happening. It arrived at a NASA facility earlier this week and is now undergoing a complete evaluation.