Since they were both dismissed your chances of getting in obviously are a lot better. Access will definitely want proof that these charges were dismissed. So, the first thing I would do is get a legal document showing from the courthouse or local police station showing that the OUI/Disorderly Conduct charges have been dismissed. Due to the fact the OUI is within the past 5 years they will make you complete a 5 year work history background rather than a 3 year. For instance, if you hire in on 7/3/12 you would have to complete your work history back to 7/3/07 to cover the 5 years. I doubt any utility will want you to complete a substance abuse evaluation if you can show that the charges were dismissed, however, some utilities tend to go above and beyond the requirements especially if they find out that charges were dismissed due to completing completing special classes etc to have the charge dismissed. Probably won't happen, but it is possible.
Just make sure you list everything and the best details possible to expedite the process. Other than that I don't think it will b e too much of an issue as long as you have paperwork. Good luck