I remember the days when this type of offense gave you a letter in your file. YIKES! I am scratching my head on this one. Com-Ed was where one went if they got busted for drugs somewhere else, as they had the most lenient policy toward offenders. Now they are being hard nosed?
Face it. It is a DUI type offense. We all know a guy who has had these in NM, Pa., Mass., NY, and Ohio and passing through a few states that don't have nukes and is still swinging a meter.
There is plenty of work out there, even for those who don't play by the rules. I would lick my wounds and exercise my options. More sins are forgiven during a heavy outage season than Yom Kippur.
So the utility has a double standard. It uses one standard for contractors in which they have zero dollars invested, and another standard for its house people in which they have invested many hours of training. They didn't fire you and you are not black balled. The utility considers you a risk until you have proved you no longer have a drinking problem. They define a "drinking problem" as, "if your drinking effects your ability to work it is a problem." All you have to do is to find 12 people who agree with you.
If you indeed have 20 years in the industry young man, then you would be a returnee at other locations which should welcome you back with open arms. Pay your 3 years dues, give your liver a break, and then attempt a return.