Free software tools developed for the Department of Defense (DoD)

REMChlor-MD, developed for the Department of Defense’s Environmental Security and Technology Certification Program (ESTCP), is an easy-to-use, free software tool that can assist site personnel better understand matrix diffusion and help site stakeholders determine if these processes are significant enough to cause “rebounding” of downgradient plume concentrations above remediation goals after plume remediation or isolation is complete. Having this information readily available before a remedy is implemented, could assist site stakeholders select more appropriate remedies and improve effective risk communication with regulators and the public.

REMChlor software that was developed by Dr. Ronald Falta at Clemson University. The former version of this fate and transport model allowed users to predict how remediation impacted concentration, mass, and mass discharge after remediation. The new version, REMChlor-MD, more fully incorporates the concept that low-k zones (low permeability zones such as silt, clay layers) can serve as indirect, low-level sources of contamination to transmissive zones due to matrix diffusion. This allows for better predictions and ultimately leads to improved site management.


REMChlor-MD was developed as a cost-effective management tool for addressing contamination in a broad range of geological settings. The tool allows for efficient modeling of matrix diffusion in aquitards, layered and heterogeneous systems, and rock systems with parallel fractures. The software provides a straightforward way to account for several types of source and plume remediation activities. As a screening tool, REMChlor-MD can be used by site managers and site consultants better understand the matrix diffusion and help site stakeholders determine how matrix diffusion processes can affect long-term concentration trends after remediation. It also allows users to better evaluate remediation time frames and can lead to savings in project costs.

REMChlor-MD can provide planning-level estimates of:

  • Concentration, mass, and mass discharge (sometimes called mass flux, in grams per day) in the transmissive zone caused by matrix diffusion before or after remediation;
  • Mass of contaminants at any time in the low-k zone; and
  • Concentration at any time in an observation well.

These are important estimates for answering key questions:

  • If I remediate a transmissive zone, but my remediation technology doesn’t remove contaminants from low-k zones in contact with the transmissive zone, will I be able to achieve my cleanup standards?
  • How much contaminant mass could be present in low-k zones at my site?
  • If I install a permeable reactive barrier, will I have trouble achieving cleanup standards downgradient of the barrier?
  • If I remove all the DNAPL from a source zone, is there a chance groundwater concentrations will remain above MCLs?
  • How much longer might I have to wait for a source zone to achieve MCLs after the DNAPL is all gone?

Technical Support

Limited technical support is available from Shahla K. Farhat (

System Requirements

REMChlor-MD requires a computer capable of running Microsoft® Excel (2016 version 16.0.9226.2114 or newer) for Windows 7 and Windows 10.

Operation requires an IBM-compatible PC equipped with a Pentium or later processor running at a minimum of 450 MHz. A minimum of 256 MB of system memory (RAM) is strongly recommended. Computers not meeting these recommendations will experience slow running times and/or problems with memory. REMChlor-MD versions are available for both the 32-bit and 64-bit versions of Excel (the default Excel installation is 32-bit).