Project Rio Blanco is the first phase of a 3-phase program to demonstrate the potential of commercial development of a natural-gas field by nuclear stimulation techniques in the Piceance Basin in Rio Blanco County, Colorado. Because the gas is tightly held within the surrounding rock, this field cannot be developed by conventional stimulation methods. The first phase will consist of simultaneously detonating 3 nuclear explosives at different depths within the Fort Union and Mesaverde formations. The detonation of the explosives is designed to stimulate a 1,350-ft vertical section of the Fort Union and Mesaverde formations. After a 3-mo. waiting period, a reentry well will be drilled into the gas-filled chimney, and the reservoir testing and evaluation will start. Because of the extensive detail required in planning Project Rio Blanco, the Definition Plan is presented in 3 volumes. The tasks needed for the operational scope of work related to the detonation such as site construction, power installation and distribution, drilling of the emplacement well, stemming plans, seismic effects documentation, and ground-water protection program are discussed in V. 2.