This guide provides a method to assess potential fire development in drum storage facilities. The mechanism of fire propagation/spread through stored drum arrays is a complex process. It involves flame heat transfer, transient conduction,convection, and radiation between drums (stored in an array configuration). There are several phenomena which may occur when drums are exposed to fire. The most dramatic is violent lid failure which results in total lid removal. When a drum loses its lid due to fire exposure, some or all of the contents may be ejected from the drum, and both the ejected combustible material and the combustible contents remaining within the container will burn. The scope of this guide is limited to storage arrays of steel drums containing combustible (primarily Class A) and noncombustible contents. Class B combustibles may be included in small amounts as free liquid within the solid waste contents.Storage arrays, which are anticipated in this guide, include single or multi-tier palletized (steel or wood pallets) drums,high rack storage of drums, and stacked arrays of drums where plywood sheets are used between tiers. The purpose of this guide is to describe a simple methodology that estimates the consequences of a fire in drum storage arrays. The extent of fire development and the resulting heat release rates can be estimated. Release fractions applicable to this type of storage are not addressed, and the transport of contaminants away from the source is not addressed. However, such assessments require the amount of combustible material consumed and the surface area of this burning material. The methods included in this guide do provide this information.