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Regulatory and Investigative Treatment Zone Model (RITZ)

RITZ is a screening 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.

RITZ is based on a series of closed-form analytical equations. It assumes that waste material is uniformly 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.

RITZ is menu-driven and facilitates interactive data entry. The program produces graphical and tabular output. The documentation includes installation instructions and a user's manual.

Version 2.12
Release Date January 1988
Operating System DOS

Minimum System Requirements

To run RITZ, you will need the following:

  • IBM PC/AT or compatible
  • DOS version 2.0 (or higher)
  • Color graphic adapter (CGA) board
  • 640 KB of RAM
  • Math co-processor (recommended)


RITZ Program Files (ZIP)(94 K)

US EPA. (1988) "Interactive Simulation of the Fate of Hazardous Chemicals During Land Treatment of Oily Wastes: RITZ User’s Guide." Publication EPA/600/8-88/001.

Installation Instructions

  1. Go to Windows Explorer and create a directory named RITZ.
  2. Download the program files and user's manual to the new directory.
  3. Unzip the program files to the RITZ directory.
  4. Review the user’s manual for instruction on running the model.