Quoted from: https://www.epa.gov/water-research/vadose-zone-leaching-vleach 

VLEACH is a one-dimensional, finite difference model for making preliminary assessments of the effects on groundwater from the leaching of volatile, sorbed contaminants through the vadose zone. The program models four main processes: liquid-phase advection, solid-phase sorption, vapor-phase diffusion, and three-phase equilibration. In an individual run, VLEACH can simulate leaching in a number of distinct polygons, which may differ in terms of soil properties, recharge rates, depth of water, or initial conditions. Modeling results in an overall, area-weighted assessment of ground-water impact.

Minimum System Requirements

To run VLEACH, you will need the following:

• IBM PC/AT or compatible
• Windows 98 or higher
• Microsoft .Net Framework

Downloads

VLEACH Setup (EXE)(6 MB)

VLEACH, A One-Dimensional Finite Difference Vadose Zone Leaching Model, Version 2.2

Installation Instructions

1. Download the VLEACHsetup.exe file onto your hard drive.
2. Run the VLEACHsetup.exe file. You will be guided through the installation process.
3. The User's Manual (vleach.pdf) comes with the installation and is accessible from within the program.

If your operating system is older than Windows XP, you will need to download and install the following file:

VLEACH .NET (EXE)(21 MB)