FOOTPRINT: A Screening Model for Estimating the Area of a Plume Produced From Gasoline Containing Ethanol

FOOTPRINT is a simple, user-friendly screening model used to estimate the length and surface area of benzene, toluene, ethylbenzene, and xylene (BTEX) plumes in groundwater, produced from a gasoline spill that contains ethanol. Ethanol has a potential negative impact on the natural biodegradation of BTEX compounds in groundwater. The primary objective of the software is to predict the increase in surface area of the plume of BTEX compounds or any other chemical of concern (COC) due to the presence of ethanol in groundwater. FOOTPRINT estimates the area of a plume of particular BTEX compounds that are contained within two biodegradation zones:

  • A zone that is immediately adjacent to the source, where ethanol is present in high concentration and no biodegradation of the BTEX compounds (or other COC) is allowed
  • A second zone, where the ethanol concentration is negligible due to the natural biodegradation of ethanol in the first zone and biodegradation of the BTEX compound (or other COC) contributes to attenuation in concentration of the BTEX compounds

FOOTPRINT is based on the modified version of the Domenico model (1987) published by Martin-Hayden and Robbins (1997). This model is an approximate analytical solution of the advective-dispersive solute transport equation with first-order decay. The model of Martin- Hayden and Robbins (1997) was further modified in FOOTPRINT to allow zero-order decay as well (see Appendix B of the user’s manual for details). As a result, FOOTPRINT can independently describe the natural biodegradation of ethanol and/or the BTEX compound with either a zero-order rate constant or a first-order constant. FOOTPRINT can also be used to estimate the surface area of the plume and the concentration at any given point within the plume when the COC is decaying at a constant rate (first- or zero-order) in the absence of ethanol.

Version 1.0
Release Date June 2008
Development Status General Release
Operating System Window 98/XP

Minimum System Requirements

To run FOOTPRINT, you will need the following:

  • IBM PC/AT or compatible
  • Windows 98 or XP
  • Microsoft .Net Framework
  • Microsoft Excel 2003 or earlier



US EPA. (2008) FOOTPRINT (A Screening Model for Estimating the Area of a Plume Produced From Gasoline Containing Ethanol. Publication No. EPA/600/R-08/058.

Note: The user’s manual comes with the installation and is accessible from within the program.

Installation Instructions

  1. Download the FOOTPRINTsetup.exe file onto your hard drive.
  2. Run the FOOTPRINTsetup.exe file. You will be guided through the installation process.