Knowledge of the principles, methods, and tools employed in the general operation of engines, pumps, valves, motors, and related equipment; general maintenance work; safe work practices; principles and methods of biological and chemical sewage analyses, effects and problems of industrial waste in water/wastewater treatment processes, principles of supervision. The work areas may be indoor, outdoor, have loud noise, active machinery, high pressure fluid systems, electrical equipment, confined spaces, heights and depths, fumes, air borne particles, noxious gases, and chemicals.