(a) When the director is satisfied that an applicant is qualified, by examination or otherwise, the director shall issue a certificate attesting to the competency of the applicant as an operator. The certificate shall indicate the classification of works which the operator is qualified to supervise.
(b) Certificates of proper classifications shall be issued without examination to persons certified by a governing body or owner to have been the operator of a treatment plant or a water distribution system on September 28, 1971. A certificate so issued will be valid only for that particular treatment plant or system, but shall remain in effect three years, unless revoked by the director as provided in this chapter. All certificates shall be renewed every three years.
(c) Certificates in appropriate classification shall be issued to operators who, on September 28, 1971, hold certificates of competency attained by examination under the voluntary certification program sponsored jointly by the State Department of Health and the Alabama Water and Pollution Control Association.