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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. RITZ is distributed on a DOS-formatted disk containing source code and executable image. The documentation includes installation instructions and a user's manual.


Version 2.12
Release Date January 1988
Development Status general release
Development Information  
Operating System DOS
Development Language  
Intended Audience  
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Minimum System Requirements

To run RITZ, you will need the following:

Unzipping SoftwareExit EPA disclaimer

You will need unzipping (compression) software to uncompress ZIP files. If you need to load unzipping software on your computer, free software is available for download on the internet at the following sites:


Two files are available for download:

Program files (ZIP)(94 KB)

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.

You will need Adobe Reader to view some of the files on this page.
See EPA's PDF page to learn more.


Office of Research & Development | National Risk Management Research Laboratory

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