What are the DISA requirements for returning to work after failing a drug screen?

Here is a link to DISA guidelines. It says you have to complete a Rehab program approved by the Return-to-Duty Dept. prior to going back to work. No time frame is given.

http://www.energytran.com/wp-content/uploads/2013/11/DISA-Contractors-Consortium-Substance-Abuse-Policy.pdf