When an employee has been assigned in writing by the department head or his/her representative to perform the work of a permanent position having a different class and being paid at a higher rate, and if he/she has worked in such class for more than five consecutive work days (or four consecutive workdays for employees on a “4/10” shift), he/she shall be entitled to payment for the higher class as prescribed for promotions in subsection 5.6, starting on the sixth workday and continuing during the period of temporary assignment, under the conditions specified below:
(1) The assignment is caused by the absence of the incumbent;
(2) The employee performs the duties regularly performed by the absent incumbent, and these duties are clearly not included in the job description of his/her regular class¬;
(3) The temporary assignment to work out of class which extends beyond twenty (20) workdays must be approved by the Human Resources Director, a copy of the approval form to be given to the employee; and
(4) A copy of the department head’s written approval must be submitted in advance to the Human Resources Director. If the Director determines that he/she will not approve pay for work in the higher class which exceeds twenty (20) workdays, the employee will be so notified and have the opportunity to discuss this matter with the Director whose decision shall be final.