A Source Screening Module (SSM) has been developed in MS Excel to support preliminary evaluation of the threat posed by vadose zone waste sites on groundwater quality.

This tool implements analytical solutions to simulate contaminant transport through the unsaturated and saturated zones to predict time-varying concentrations at potential groundwater receptors.  The SSM integrates several transport processes in a single simulation that is implemented within a user-friendly, Microsoft Excel TM -based interface.

The conceptual model for the SSM is shown schematically in Figure 1. The SSM integrates three sequential calculations into a single simulation:

  1. Calculation of pore water concentration from measured soil concentration in the source area;
  2. Transport across the vadose zone; and
  3. Dilution and transport in the saturated zone beneath the source, including advective-dispersive-reactive transport to a potential receptor.


Figure 1 Conceptual model for the Source Screening Module

At complex sites there may be many potential sources of contaminants within the vadose zone.  Screening-level analyses are useful to identify which potential source areas should be the focus of detailed investigation and analysis.  The SSM is an easy-to-use tool that implements exact solutions for idealized conditions with the accessible Microsoft Excel environment.

The SSM combines solutions to transport processes in the source, vadose, and saturated zones into a single integrated package. It can be used as a screening level calculator to estimate conservative solutions in a relatively short period of time and to classify or rank potential source areas at multi-source sites into high and low risk areas, prioritizing assessment of the areas that need more rigorous analysis using comprehensive numerical simulators. The module can also be used for educational purposes and experimental design.


These programs are provided FREE of charge. The authors request only that application of the software and production of results using the code is accompanied by a suitable acknowledgment. The software is provided "AS IS", without warranty of any kind, including without limitation the warranties of merchantability, fitness for a particular purpose and non-infringement. The entire risk and responsibility as to the quality and performance of the Software is borne by the user. The author(s) disclaim all other warranties.