(a) A certificate approved by the board and issued by the department shall authorize the individual to whom it is issued to operate a wastewater system in accordance with the following classification:

“Class A certificate.” Wastewater systems of unlimited permitted discharge flow.

“Class B certificate.” Wastewater systems with a permitted average daily discharge flow equal to or less than five million gallons.

“Class C certificate.” Wastewater systems with a permitted average daily discharge flow equal to or less than one million gallons.

“Class D certificate.” Wastewater systems with a permitted average daily discharge flow equal to or less than one hundred thousand gallons.

“Class E certificate.” Wastewater systems consisting only of collection facilities with pumping stations which discharge untreated wastewater into another system.

(b) In order to be eligible for certification, an applicant shall have had sufficient experience acceptable to the board in the operation of wastewater systems. In determining whether minimum experience requirements are met, the board may make reasonable allowance for education and training in the field of wastewater system operation and for training and experience in allied fields.

(c) In order to be eligible for renewal of certification, in addition to submitting an application and the appropriate fee, an applicant:

(d) No operator shall make any process control decisions unless the individual is in possession of a valid certificate for the applicable classification and subclassification assigned to the wastewater system.