Federal Transit Authority FTA, Click here 49 CFR part 655 See 655.3 "Applicability" for clarification of which companies and drivers fall under this regulation.
If you employ safety-sensitive workers who must have Department of Transportation (DOT) drug and alcohol tests, or you manage a DOT drug or alcohol testing program, this publication can help you understand how to run an excellent program that meets DOT requirements.
When you have any drug or alcohol violation you will need to be evaluated by a Substance Abuse Professional (SAP) in order to develop a return to duty program. Follow this link for a list of qualifies SAP's. https://www.naadac.org/sap-directory
Please note that this is just one option for finding an SAP. Regardless of how you connect with an SAP be sure to confirm that they have successfully obtained the U.S. Department of Transportation's Substance Abuse Professionals (SAP) Qualification