(1)    Powers and duties. The department shall by rule establish an examining program for the certification of soil testers, setting such standards as the department finds necessary to accomplish the purposes of this chapter. Such standards shall include formal written examinations for all applicants. The department shall charge applicants for the cost of examination and certification. After July 1, 1974, no person may construct soil bore holes or conduct soil percolation tests or other similar tests specified by the department that relate to private on-site wastewater treatment systems unless the person holds a valid certificate issued under this section.

   (3)   Plumbers may be soil testers. A plumber may also be a soil tester and install any system after approval of the site or project by the department or the governmental unit responsible for the regulation of private on-site wastewater treatment systems.