Free Software (Freeware)
MAROS
MAROS is a decision support tool based on statistical methods applied to site-specific data that accounts for relevant current and historical site data as well as hydrogeologic factors (e.g. seepage velocity) and the location of potential receptors (e.g., wells, discharge points, or property boundaries).
Animated Information System (AIS) for Groundwater Assessment and Remediation
The Animated Information System (AIS) for Groundwater Assessment and Remediation was developed to help facilitate an understanding of hydrogeology, contaminant migration in soil and groundwater, site assessment, and remediation. The AIS software provides a visualization approach that incorporates 3-D animation and state-of-the-art graphics into an interactive format. The tool focuses on petroleum releases from underground storage tanks (USTs), but many of the concepts have much broader applicability. The AIS can be used as a platform to introduce key concepts related to most sites and important regulatory issues.
BIOCHLOR
BIOCHLOR is a screening model that simulates remediation by natural attenuation of dissolved solvents at chlorinated solvent release sites. BIOCHLOR can be used to simulate solute transport without decay and solute transport with biodegredation modeled as a sequential first-order process within one or two different reaction zones.

BIOBALANCE Tool Kit
The mass balance paradigm is an important new approach to evaluating Monitored Natural Attenuation (MNA) at chlorinated solvent sites.

BIOSCREEN
BIOSCREEN is a screening model which simulates remediation through natural attenuation of dissolved hydrocarbons at petroleum fuel release sites.

Groundwater Sensitivity Toolkit
The Groundwater Sensitivity Toolkit was developed by GSI for the American Petroleum Institute and the California MTBE Research Partnership.

GSI Mann-Kendall Toolkit
The GSI Mann-Kendall Toolkit is a free, simple, easy-to-use software tool to help environmental professionals efficiently conduct concentration trend analyses for any groundwater constituent.

MAROS
MAROS provides site managers with a strategy for formulating appropriate long-term groundwater monitoring programs that can be implemented at lower costs.

Mass Flux Toolkit
The Mass Flux Tool Kit, developed for the Department of Defense ESTCP program, 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.

Matrix Diffusion Toolkit
The Matrix Diffusion Toolkit can assist site personnel to effectively and efficiently estimate what effects matrix diffusion will have at their site, and transfer the results to stakeholders.

MODFLOW-USG
MODFLOW-USG is an unstructured grid version of MODFLOW and was created to provide flexibility in gridding for MODFLOW solutions.

RTM-CSIA-MNA
Guidance and Software for interpretation of Compound-Specific Isotope Analysis Data with Reactive Transport Modeling for Improved Monitored Natural Attenuation of Chlorinated Solvent Plumes
SERDP: Source Depletion Decision Support System
The Source Depletion Decision Support System, developed by GSI Environmental Inc., with funding provided by the Department of Defense Strategic Environmental Research and Development Program (SERDP), is a software tool designed to aid the decision-making process for remediation of dense non-aqueous phase liquid (DNAPL) source zones.

SourceDK
SourceDK is a computer decision support system for estimating remediation timeframes and assessing the uncertainty associated with those estimates.

Source History Tool
The Source History Tool, developed for the Department of Defense’s ESTCP program, is an easy-to-use, comprehensive, free software tool that can assist site personnel reconstruct long-term contaminant source histories that extend back to the beginning of the original source release.

REMChlor-MD (Version 1.0)
REMChlor-MD, developed for the Department of Defense ESTCP program, is an easy-to-use, free software tool that can assist site personnel better understand matrix diffusion and help site stakeholders determine if matrix diffusion processes are significant enough to cause “rebounding” of downgradient plume concentrations above remediation goals after plume remediation or isolation is complete.

PHT-USG module of BTN Package
PHT-USG is a coupling of USG-Transport with PHREEQC, to provide an unstructured transport framework for solving geochemical reactions in the subsurface.
