An interactive software system was developed to enable decision makers to simulate the movement and fate of hazardous chemicals during land treatment of oily wastes. The mathematical model known as the Regulatory and Investigative Treatment Zone Model or RITZ was developed and published earlier by Short (1985). The model incorporates the influence of oil in the sludge, water movement, volatilization, and degradation upon the transport and fate of a hazardous chemical. The manual describes the conceptual framework and assumptions used by Short (1985) in developing the model. It then explains the microcomputer hardware and software requirements, the input parameters for the model, and the graphical and tabular outputs which can be selected. Illustrations of the use of the software are also included. Software Description: The software is written in TurboPascal for implementation on an IBM-PC, XT, AT or compatible microcomputer using the PC-DOS or MS-DOS 2.0 or later operating system. Memory requirement is 265K. The system requires an 8087 or 80287 math coprocessor.