[en] This document is to establish the hazard classification of single shell watch list tanks according to National Fire Protection Association (NFPA) criteria and sound engineering judgment. Establishing the hazard classification is necessary to determine the appropriate wiring methods and installation of electrical and mechanical equipment assure safety in an atmosphere that may be hazardous. The tanks have been placed on the flammable gas watch list because their waste types are similar to those in tanks that exhibit episodic behavior and/or unexplained growth of the waste-level height occuring over time. They contain mostly solid wastes