How do I know the operators of the water production facilities are qualified?

Our operators are required by DHH to possess a Class 3 Water Production, Treatment & Distribution Certificate. There are 4 levels of Production Treatment & Distribution. The level you need is based on population served. Currently the Plant Supervisor holds all three certificates of Class 4. The Foreman holds Class 3's & another operator possesses Class 2's. They are also required to maintain 24 hours of certified training to keep their certification.