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Hazardous Waste

Hazardous Waste Delisting Risk Assessment Software (DRAS)

DRAS is a user-friendly, stand-alone, Microsoft Windows-based software program that calculates the potential human health risks associated with disposing a specific facility’s given waste stream in a landfill or surface impoundment.  DRAS was specifically designed to address the Criteria for Listing Hazardous Waste identified in Title 40 Code of Federal Regulations 40 CFR §261.11(a)(3), a requirement for evaluating proposed hazardous waste delistings.  DRAS performs a multi-pathway and multi-chemical risk assessment to model mismanagement scenarios at Subtitle D landfills or surface impoundments instead of under RCRA Subtitle C requirements.

EPA developed DRAS to be simple to use by anyone with little background in human health risk assessment.  To start, the user enters a few simple input parameters, selects chemicals of concern from a list, and enters the chemical concentrations.  For a given waste stream, DRAS calculates the waste's aggregate risks and also back-calculates each waste constituent's maximum allowable concentration permissible for delisting.  In addition, DRAS compares modeled surface water chemical concentrations from disposal of a given waste stream to ecological benchmarks.   

DRAS requires the user to assign a target cancer risk and hazard index. For example, a user can choose a target cancer risk of 1×10-6 and a target hazard index of 1.0, which is what EPA Region 5 requires to be used in Federal delisting determinations. Please refer to your delisting authority for the correct risk target information to use.

DRAS is a risk assessment tool and, therefore, can only provide risk analyses based on the information input into the program. The risk assessment results are only one of several factors in an Agency’s delisting decision. The risk-based approach combines state-of-the-art fate and transport modeling with standardized exposure assessment algorithms to provide sound risk assessment. EPA has improved several versions of DRAS with a number of modifications and upgrades.

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Background and Updates

EPA originally developed DRAS in 1998 to analyze human health risks of wastes petitioned for delisting under Title 40 of the Code of Federal Regulations (CFR) in Section 260.22.  EPA updated DRAS in September of 2010 (DRAS 3) and in August 2020 (DRAS 4).

DRAS 4 includes several updates summarized below (see DRAS 4 User Manual and DTSD for detailed explanations):

  • Improved user interface.
  • Many updated parameter values in the DRAS 4 database to reflect current values used by EPA (such as chemical toxicity values) and to reflect experimentally measured values (such as Henry’s law constants and log Octanol/water partition coefficients).  
  • Resolved computational problems with the surface impoundment pathway including simplifying the input parameters.   
  • Improved aggregate calculation of risk and hazard to correctly handle instances of non-detects in the sample data.
  • Restored ability to add waste constituents that are not in the DRAS database.
  • Modernized DRAS 4 software platforms for the risk engine, the graphical user-interface, and the database to allow future improvements.  The specific software for these three program elements were chosen for their estimated operational longevity.

For Current DRAS 3 Users

DRAS 4 is an improved version of DRAS, providing updated toxicity parameter values, technical corrections to fate and transport calculations, and an improved user interface.  EPA recommends that current DRAS 3 users download the DRAS 4 software and then re-enter information into DRAS 4.  A DRAS 3 project cannot be loaded into DRAS 4; therefore, it will be necessary to enter all information into the program again.

If you require the DRAS 3 software, or have questions, please contact EPA for assistance.

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System Requirements

  • Processor                                 1 GHz or faster (Windows 10 requirement)
  • Operating System                 Windows 10 64-bit
  • RAM                                            4 GB
  • Free Hard Disk Space          200 MB

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Downloading the Delisting Risk Assessment Software

  1. To install the Microsoft Windows compatible DRAS 4 software, click on the following link to download the executable program (DRAS4_20200803.exe) (54 MB, August 2020) to your computer.
    Delisting Risk Assessment Software (DRAS) version 4.0 (59 MB)
  2. Save the DRAS4_20200803.exe file to your hard drive. 
  3. Double-click the DRAS4_20200803.exe file to open it and run the program. 

The DRAS 4 program contains an updated DRAS 4 User Manual and an updated DTSD.  In DRAS 4, click “Manual” from the Toolbar to access these documents.  In addition, these support documents plus a new Quick Start Guide are available for download by following the links further down on this page.    

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Quick Start Guide

The Quick Start Guide  provides simple instructions for setting up a project in DRAS 4, running the risk computational engine, and viewing and saving tabulated results. 


RCRA Delisting Technical Support Document (DTSD)

The DTSD presents extensive information delineating all chemical release, exposure and risk assessment algorithms employed by the DRAS program. Appendix A-1 of the DTSD contains the chemical-specific toxicity data and parameter details that are used in the risk calculations along with reference citations for the values.  Anyone wishing to gain technical insight into the RCRA delisting risk-based process may review information provided in the document. EPA updated the DTSD in October 2008 and in August 2020.

The DTSD can be opened from within DRAS 4. You can also read the DTSD as a separate set of documents.

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DRAS 4 User Manual

The DRAS 4 User Manual provides the DRAS 4 program's system requirements as well as an overview on how to use the DRAS 4 software.  The DRAS 4 User Manual can be opened from within DRAS 4.  EPA updated the current version of the DRAS User Manual for the DRAS 4 version release.


Who to Contact for Help

For questions about the delisting process in your state or region, contact your U.S. EPA or State representative.

To contact someone directly about DRAS 4, use the Comments and Registration form.

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