Patterson said most of the inpatient programs such as the one Pachall will enter are 30 to 60 days. If Pachall completes the treatment, the door remains open for him to return to school and the team.
"Hopefully, what our plan is that he (Pachall) gets himself right and keeps the door open for us as far as an opportunity for him to be able to come back here and enroll in the spring," Patterson said. "He would be able to graduate in two semesters, which is the ultimate goal for us. Also, we'd get a great kid and also a good quarterback back."
Patterson said he met with Pachall and his parents earlier this week. The coach also met with the university's chancellor and athletic director on Sunday.
"There was only one way he was going to change the path that he was on," Patterson said. "And that was he just needed to step away from it all. I think it's the best decision for this football team and Casey Pachall."
Patterson said Pachall may already be at the facility, less than a week after being arrested on suspicion of driving while intoxicated.
In August, TCU confirmed that Pachall had failed a university-administered drug test on Feb. 1. That was just two weeks after four TCU football players were arrested in a campus drug bust, and Pachall told police he had used drugs.
"I don't think one game, three games would have made a difference," Patterson said. "You try to change people's lives. That's what this is all about."
Redshirt freshman Trevone Boykin, who threw for 270 yards in a loss to Iowa State last week, will make his second start in Pachall's place on Saturday against Baylor. Pachall had thrown for 948 yards, 10 touchdowns and an interception in the first four games.
Information from The Associated Press was used in this report.