The personnel commission may authorize the extension of a provisional employee’s assignment for a period not to exceed 36 working days provided the following requirements are met:

1. (a) An examination for the class was completed during the first 90 working days of his provisional assignment.

2. (b) Evidence satisfactory to the personnel commission is presented indicating:

   1. (1) That an adequate recruitment effort has been and is being made.
   2. (2) That extension of the provisional assignment is necessary to carry on vital functions of the district.
   3. (3) That the position cannot be satisfactorily filled by use of other employment lists or procedures.