Regulatory and Investigative Treatment Zone Model 'RITZ' is a screening level model for simulation of unsaturated zone flow and transport of oily wastes during land treatment. RITZ was developed to help decision makers systematically estimate the movement and fate of hazardous chemicals during land treatment of oily wastes. The model considers the downward movement of the pollutant with the soil solution, volatilization, and loss to the atmosphere, and degradation. The model incorporates the influence of oil upon the transport and fate of the pollutant. The model is based on a series of closed-form analytical equations. The model assumes that waste material is funiformly mixed in the plow zone, that the oil in the waste material is immobile, and that the soil properties are uniform from the soil surface to the bottom of the treatment zone. Furthermore, the flux of water is considered uniform throughout the treatment site and throughout time, and hydrodynamic dispersion is insignificant and can be neglected. The partitioning of pollutant between the liquid, soil, vapor, and oil phases is described by linear equilibrium isotherms. Degradation of pollutant and oil is described as a first-order process. The water content of the soil is related to the hydraulic conductivity as described by Clapp and Hornberger.

RITZ is menu-driven and facilitates interactive data entry. The program produces graphical and tabular output. RITZ is distributed on a DOS-formatted disk containing source code and executable image. The documentation includes installation instructions and the EPA user's manual.


Intel 80i86 based computer
640 Kb RAM
about 1 Mb free disk space
DOS 2.0 or higher
CGA graphics
math co-processor recommended


Authors: D.L. Nofziger (Oklahoma State Un.), J.R. Williams, and T.E. Short (U.S. EPA)