Thanks for your question.
Ideally, you should communicate your observations to the HR team of that organization so they can follow up, OR to your HR team so your team can communicate those concerns.
If you don't feel comfortable communicating directly -- is it physically possible for you to leave an anonymous note to that organization's HR team or senior leadership identifying the days/times where you observed employees under the influence of drugs and/or alcohol?
Either way -- you're going to want to put the client's HR team or leadership on notice that they have a drug and alcohol issue in the workplace that needs addressing.
Lastly, if you like -- you can provide the details of the situation through this channel since Emtrain Experts are a neutral third party and we can communicate the details of your concern to your HR team for you -- leaving you anonymous.
Workplace Harassment Expert
February 9 2018