SERDP-ESTCP

SERDP/ESTCP Tools

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

GSI has been a leader in creating innovative and powerful software tools for the Department of Defense that help improve decision-making at contaminated sites. Each of these tools have been developed through the Strategic Environmental Research and Development Program (SERDP) or the Environmental Security Technology Certification Program (ESTCP) (https://www.serdp-estcp.org/) Development of these tools has relied on GSI’s extensive expertise in contaminant fate and transport modeling, data analysis/visualization, and technology transfer. In many cases, GSI has collaborated with top environmental researchers at academic institutions to leverage additional know-how during software development.

The tools are designed to solve complex problems while utilizing readily accessible platforms with simple user interfaces. They are free to both DoD and to the public, ensuring that they can be utilized by a wide audience and making them valuable resources for management of contaminated sites.

Key SERDP/ESTCP software tools developed by GSI include:

  • REMChlor-MD
  • Matrix Diffusion Toolkit
  • Mass Flux Toolkit
  • Source History Tool
  • SERDP Source Depletion Decision Support System (DSS)

REMChlor-MD

Predicting how matrix diffusion impacts remediation performance

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.

This tool is an update of the popular 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.

Matrix Diffusion Toolkit

Practical tool for understanding complex process

The Matrix Diffusion Toolkit, developed for the Department of Defense’s Environmental Security Technology Certification Program (ESTCP), is a free software tool that can assist site personnel to effectively and efficiently estimate what effects matrix diffusion will have at their site, and transfer the results to stakeholders. Matrix diffusion describes the process where compounds that have diffused into low-permeability zones such as silt and clay layers in the subsurface serve as indirect, low-level sources of contamination to transmissive zones over time. This process has the potential to sustain dissolved contaminant concentrations in groundwater after the source is removed or after remediation removes or isolates contamination from transmissive compartments. Quantifying how matrix diffusion processes may influence decisions is becoming a critical part of long-term management of many contaminated sites.

The Toolkit is Microsoft® Excel-based and provides the following, easy-to-use tools to calculate and evaluate matrix diffusion effects:

1) Square Root Model:
A module to provide planning-level estimates of the mass discharge (in units of grams per day) caused by release from a low-k diffusion-dominated unit (typically silt or clay) into a high permeability advection-dominated unit (typically sand or gravel). Estimates of concentration and mass remaining in the high permeability unit, after the source is removed, are also provided.

Additionally, the Square Root Model also utilizes a Monte Carlo-type approach to analyze uncertainty in the actual concentration, porosity, apparent tortuosity factor exponent, and retardation factor measurements. With this tool, groundwater practitioners can estimate the accuracy of the hydrologic measurements that are being used for the matrix diffusion calculation.

2) Dandy-Sale Model:
A module allowing users to perform: i) contaminant transport via advection and transverse diffusion in the transmissive layer, and ii) transport via transverse diffusion in the low-k zone. The module provides planning-level estimates of:

Low-k Zone:
1. Aqueous, sorbed, and total concentration; and
2. Aqueous, sorbed, and total mass.

Transmissive Zone:
1. Aqueous, sorbed, and total concentration;
2. Aqueous, sorbed, and total mass; and
3. Mass discharge.

3) Matrix Diffusion Related Tools
An additional feature that provides a review of theory and methods related to matrix diffusion:

  • NAPL Dissolution Calculator: a module that estimates the transverse diffusion of contaminants into the groundwater passing over the top of a Non-aqueous Phase Liquid (NAPL) pool and the transverse diffusion of contaminants into the low-k unit underlying the pool;
  • Plume Magnitude Information: a summary of the Plume Magnitude Classification System (Newell et al., 2011) and its application to site investigation and remediation;
  • Low-k Zone Remediation Alternatives: a summary of current alternatives for the remediation of low-k zones; and
  • 14-Compartment Model: a discussion on the quantitative application of the 14 Compartment Model (Sale et al., 2008a).

Mass Flux Toolkit

Powerful software tool for estimating key decision metric.

The Mass Flux Toolkit, developed for the Department of Defense’s Environmental Security Technology Certification Program (ESTCP), is an easy-to-use, Microsoft® Excel based software tool that enables users to learn about different mass flux approaches, calculate mass flux from transect data, and apply mass flux values to manage groundwater plumes. Mass flux has increasingly become an important metric for decision making at complex contaminated sites (See ITRC guidance on mass flux), and this software provides the user with the knowledge and tools they need to apply this concept to actual sites.

The Toolkit presents the user with three main options:

  • A module to calculate the total mass flux across one or more transects of a plume, calculate the uncertainty in the calculation, and plot mass flux vs. distance to show the effect of remediation/impact of natural attenuation processes.
  • A module allowing users to perform critical dilution calculations for plumes approaching production wells or streams. An additional feature calculates the capture zone of the supply well and compares it to the transect used to calculate the mass flux, directing the user to alter the transect dimensions if the transect does not encompass the capture zone.
  • A module that provides a review of theory and methods of estimating mass flux.

Uncertainty in mass flux estimates is a key issue in using mass flux as a metric. The Toolkit provides three options for analyzing uncertainty in the total mass flux estimates derived from the transect method. One option utilizes the Monte Carlo approach to analyze uncertainty in the actual concentration, hydraulic conductivity, and gradient measurements. With this tool, groundwater practitioners can estimate the accuracy of the hydrologic measurements that are being used for the mass flux calculation. The second option provides a tool for estimating the contribution of each individual observation to the total mass flux. The third method shows the uncertainty involved in the interpolation scheme that is used to calculate mass flux.

Source History Tool

Reconstruct how source has changed over time

The Source History Tool was developed for the Department of Defense’s Environmental Security Technology Certification Program (ESTCP) program to assist site personnel reconstruct long-term contaminant source histories that extend back to the beginning of the original source release. The Tool uses soil core data collected in low permeability zones (low-k zones) to make predictions about the source loading over time, in a forensic approach not unlike the evaluation of tree rings.