Local 20 Stewards during the term of their office shall have super seniority for the purpose of layoff and recall. The Steward shall be entitled to hold or exercise super seniority solely within the work unit elected. For the purpose of this section only, work unit seniority shall be defined to mean Water Reclamation Division, Refuse Section, and Landfill Section of the Solid Waste Division. They shall return to their original standing on the seniority list at the end of their terms of office.