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EPA's Region 6 Office

Serving: Arkansas, Louisiana, New Mexico, Oklahoma, Texas, and 66 Tribal Nations

Delisting Risk Assessment Software (DRAS)


The Delisting Risk Assessment Software (DRAS) is a Windows-based computer program that predicts risks to human health and the environment from the disposal of wastes to a landfill or surface impoundment. The DRAS is used to calculate potential chemical releases, fate and transport of the chemicals and to determine risk associated with exposure to the chemicals released. The DRAS is a user-friendly tool providing information necessary to delisting decision-making.

The Objective of this software program is to provide the user with an efficient and scientifically defensible means to evaluate whether a RCRA listed waste qualifies for an exclusion, or "delisting" under 40 CFR ยงยง260.20 and 260.22, with regards to toxicity. This procedure does not, in itself, determine whether a waste petitioned for an exclusion will pass or fail the delisting process.

The DRAS software program was developed by Region 6 Delisting Program, Multimedia Planning and Permitting Division, USEPA. The program has since been adopted as technical guidance for all EPA Regions. Draft version of the DRAS was provided to the Regions and HQ for beta testing in September 1999. The EPA Office of Research and Development (ORD) provided internal peer review comments during the fall of 1999. Complete Response to Comments package on Regional, OSW and ORD comments was completed in June 2000. Region 6 revised the software code and the technical documentation in response to regional, OSW, and ORD comments.


The methods used to determine risk associated with the waste disposal scenarios are based on Agency risk assessment algorithms. The DRAS determines the risks associated with exposure to adult and child receptors. The assessment methodology used to calculate chemical concentrations in media at the point of exposure are based on Agency fate and transport mechanisms. The DRAS evaluates chemical releases from a landfill or surface impoundment to various surface media and groundwater. The DRAS evaluates chemical releases of volatiles and particulates to air, runoff to streams and infiltration into groundwater. Surface exposure pathways include: inhalation of contaminated air, ingestion of contaminated soils, surface water and fish. Release equations for landfill volatile emissions and transport equations for fish contamination have been revised. Groundwater exposure pathways include ingestion, dermal absorption (during bathing) and inhalation (during showering) of contaminated groundwater. The dermal absorption and inhalation of contaminated groundwater are recently added exposure pathway analyses.


The DRAS program was created using Microsoft VisualBasic 6.0 software programming. DRAS requires approximately 40 MB hard drive space. 64 MB of RAM is recommended to run the program. The time required to download this software program will depend on the speed of the internet connection. Download time could run from an hour to less than a minute depending on whether an individual is using a 28.8 modem or a T1 connection.

After saving the dras.exe file to your hard drive, double click the file and it will uncompress 9 files. Then double click on the setup.exe file to begin installation. If you do not have a high speed internet connection, or if you have any problems downloading this large file, please call or email at the address below.

For information on the DRAS, please contact:

Dr. Michael Morton
OK/TX RCRA Permits Section (6PD-O)
Multimedia Planning and Permitting Division
1445 Ross Avenue
Dallas, Texas 75202
(214)665-8329 or E-Mail Address: E-Mail:

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