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User’s Guide 

Delisting Risk Assessment Software (DRAS) 

Version 3.0 

October 2008 

U.S. EPA Region 5 

Chicago, Illinois 
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1 Introduction....................................................................................................................1-1

1.1 Objectives .................................................................................................................1-1

2 System Requirements and Installation ......................................................................2-1

3 Quick User’s Guide.......................................................................................................3-1

4 Overview.........................................................................................................................4-1

5 Detailed Description .....................................................................................................5-1

5.1 Start-Up.....................................................................................................................5-1

5.2 Main Menu ................................................................................................................5-1

5.3 Steps 1-3 – Entering Facility Information .................................................................5-4

5.4 Steps 4&5 – Selecting Chemicals of Concern .........................................................5-6

6 Results............................................................................................................................6-1
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1 Introduction 

The U.S. Environmental Protection Agency (EPA) developed this User’s Guide as part of the 

Hazardous Waste Delisting Program. The Region 6 Delisting Program originally developed 

The Delisting Risk Assessment Software (DRAS) to compute risks and hazards associated 

with individual waste streams for delisting petitions. Regions 5 and 6 updated DRAS and 

released version 3.0 in October 2008. DRAS is used by several EPA Regions, numerous 

delisting-authorized states and facilities interested in delisting waste. 

DRAS was specifically designed to help determine whether a waste meets the conditions 

under Title 40 Code of Federal Regulations 40 CFR §261.11(a)(3) (Criteria for Listing 

Hazardous Waste), as well as other factors. These may include chemical constituents other 

than those for which the waste was listed that could cause the waste to be a hazardous 

waste. This guide will assist the user in applying DRAS to evaluate petitions to delist 

hazardous wastes submitted under (40 CFR) §260.22. 

DRAS performs a multi-pathway and multi-chemical risk assessment to assess the 

acceptability of a petitioned waste to be disposed into a Subtitle D landfill or surface 

impoundment. DRAS executes both forward- and back calculations. The forwardcalculation uses chemical concentrations and waste volume inputs to determine cumulative 

carcinogenic risks and hazard results. The back-calculation applies waste volume and 

acceptable risk and hazard values to calculate upper- limit allowable chemical 

concentrations in the waste. 

1.1 Objectives 

The objectives of the User’s Guide are: (1) to provide general information about DRAS; (2) 

to provide step-by-step instructions on using the software and interpreting the results of the 

risk assessment; and (3) to troubleshoot difficulties commonly encountered in installation 

and operation of the software. This information is intended to assist regulatory authorities, 

petitioners, and decision makers in the hazardous waste delisting determination process. 

Users are directed to the Delisting Technical Support Document (DTSD) for detailed 

background information about the algorithms, equations, and the dilution-attenuation factors 

(DAFs) used in the risk assessment. The DTSD is provided with the software and in most 

installations, can be accessed directly from within the program by selecting the Documents 

menu. In the event the link fails, the documents are located in the Documents subfolder 

within the folder in which the program was installed. 

For additional information necessary to satisfy the information requirements of a complete 

delisting petition, Petitioners should consult their delisting regulatory authority. The Region 6 

RCRA Delisting Program Guidance Manual for the Petitioner (U.S. EPA, 1996) is also 

available with additional information for the petitioner. 
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2 System Requirements and Installation 

This section summarizes the operating system requirements for DRAS version 3.0. 

• Pentium, or compatible processor-based personal computer (PC with 1GHz or 

greater is recommended). 

• Windows 2000, or Windows XP, or later Windows versions. 

• 256 MB of RAM. 

• At least 100 MB of available hard disk space. 

• Printer for generating hard-copy reports. 

A CD-ROM drive, flash drive, or floppy drive is not necessary but can facilitate exporting of 

DRAS project files from one computer to another. 

To install DRAS version 3.0, download setup.exe to your PC, double-click setup.exe, and 

follow instructions on the screen. 
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3 Quick User’s Guide 

1. Through Start and Programs, Open DRAS version 3.0. 

2. Select New Analysis from among the Analysis Operations also along the left side of 

the screen. 

3. In the DRAS window Steps 1-3, enter values into all required fields, choose single- or 

multi-batch waste generation, enter the annual or total volume in cubic yards (for 

landfills), set target risk and hazard according to your delisting regulatory authority. 

Click Update, then To Steps 4&5. 

4. In the DRAS window Steps 4&5, use drop-down tables to add DRAS waste 

constituents to the project list and enter analytical data for total and leachate 

concentrations. Click Update Site COCs, then Run DRAS. 

5. Check the Pathways Exceeding the Delisting Limits output table for any 

concentrations exceeding target risk, hazard, or SDWA MCLs. 

6. Check the Maximum Allowable TCLP Concentrations – Groundwater Exposure 

Pathway and Maximum Allowable Total Concentrations – Surface Exposure 

Pathway output tables for allowable concentrations. 

7. Check the Aggregate Risk and Hazard Quotient Results output table for aggregate 

risks or hazards that may exceed target levels. 

8. Check the Toxicity Characteristic, Soil Saturation, and Ecological Values output table 

to confirm that none of these parameters are exceeded. 

9. Click Save Analysis and Print output tables as needed. 
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4 Overview 

DRAS assesses the carcinogenic risk and noncarcinogenic hazard associated with a 

petitioned waste’s disposal to either of two types of waste management units (WMU). These 

are a landfill and a surface impoundment. The software prompts the user to enter waste 

information which should be available from a facility’s delisting petition. Once all the general 

waste information and the chemical specific concentration data are entered, the program 

performs screening and cumulative risk and hazard calculations. 

The screening risk evaluation provides the user with Toxicity Characteristic Leachate 

Procedure (TCLP) and total waste constituent concentrations associated with the target 

carcinogenic risk level and the target hazard quotient for the most sensitive exposure 

pathway. The target carcinogenic risk and noncarcinogenic hazard must be entered by the 

user. The targets are typically set by the delisting regulatory authority applicable to your 

delisting and may vary from one jurisdiction to another due to differences in local risk 

management objectives. TCLP and total constituent concentrations derived from target risk 

and hazard settings may be used as the maximum allowable waste constituent 

concentrations for a multi-year standard exclusion (delisting). If the waste constituent 

concentration exceeds these risk-based levels, the waste may not qualify for a multi-year 

exclusion under 40 CFR §§260.20 and 260.22. 

The cumulative risk assessment provides the user with an overall carcinogenic risk and 

noncarcinogenic hazard index (HI) for the petitioned waste as a whole, summing risks 

associated with each exposure pathway for a given constituent and then summing risks for 

all waste constituents. The assessment also provides the user with the cumulative 

carcinogenic and noncarcinogenic risks associated with a specific waste constituent. If the 

waste constituent concentrations exceed the risk-based levels calculated from DRAS, the 

waste may not qualify for exclusion under 40 CFR §§260.20 and 260.22. The methods and 

data used in the determination of media waste concentrations at the point of exposure and 

the risk assessment algorithms are outlined and referenced in the DTSD. 

The results are presented in a series of tables documenting the constituents evaluated, any 

modifications to default chemical, physical, or toxicological parameters, forward estimation of 

risks by pathway and constituent, back-calculated estimation of allowable concentrations by 

pathway and constituent, estimates of aggregate risk and hazard, and a screening of 

concentrations exceeding the allowable concentrations, soil saturation, toxicity characteristic 

concentrations, or ecological screening values. 

The user may also enter the detection limit (DL) value associated with a given waste 

constituent and the program will determine the risk and hazard associated with a fraction of 

the waste constituent DL value. The default fraction used in the risk assessment is one-half 

of the detection level. The program tracks waste constituent risks associated with actual 

measured concentrations with and without out non-detects valuated at one-half of the DL. 
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5 Detailed Description 

5.1 Start-Up 

Upon opening DRAS 3.0, a small window box appears with a reminder that a number of 

changes have been made to the program. A link is provided to a more detailed summary of 

the modifications. Click No, go to program to bypass the message and open the main 

menu. 

5.2 Main Menu 

The Main Menu appears as follows: 

Existing projects are listed in a window on the left side of the screen labeled Available 

Analyses. To start a new project, select New Analysis from among the Analysis Operations

also along the left side of the screen. You can also click on the Begin a New Analysis

button located in the tool bar or by selecting New Analysis from the File Menu at the top of 

the page. This will open a window where you can enter facility information (see section 5.3). 

Note that project data entry and results screens will appear in the empty window to the right 
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within the Main Menu and the commands listed both above and to the left of the project 

window will remain during all subsequent DRAS operations. 

The other options available under Analysis Operations are: 

Open Analysis – This will open any project listed above. The user must have that project 

selected in the Available Analyses window by clicking on it once until highlighted. 

Save Analysis – This will save the project. Note: this option is only available if a project is 

open. Also, the projects are automatically saved within the DRAS database. In order to 

archive a project or move it to another computer you must use the Export Analysis

command. 

Close Analysis – This will close the project. Note: this option is only available if a project is 

open. 

Export Analysis – This will export the project as a file in a format specific to the DRAS 

software (with the extension .drs). Note: this option is only available if a project is open or is 

selected in the Available Analyses window by clicking on it once until highlighted. 

Copy Analysis – This will create a duplicate copy of a project. You can run variations of the 

same project without having to reenter data by copying the analysis and renaming it and 

saving it in the Steps 1-3 window (see Section 5.3.). 

Import Analysis – This will allow you to import a project from an archive or another 

computer by opening an existing DRAS formatted “Export” file (with the extension *.drs). 

Delete Analysis – This will delete the project file. 

Update Analysis – This function is used to update existing projects in the event a newer 

version of DRAS is issued. A duplicate of all projects imported into the Available Analyses

window will be created using physical and chemical parameters from the new version. The 

user should rename them or otherwise note they may have different results. This function 

will not update DRAS version 1.0 and 2.0 files since the version 3.0 database has been 

restructured. 

Delisting Technical Support Document (DTSD) 

A link to the Delisting Technical Support Documents is provided down the left side of the 

screen below the Analysis Operations. Clicking on these will open the documents in 

portable document format in the project window to the right. The same documents are also 

available under the Documents sub-menu at the top of the page. In the event the links fail, 

which can happen depending how your portable document format viewer is installed, you 

can access these files from the Documents sub folder located in the folder in which you 

installed the DRAS. 
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Tool Bar and Menu

A number of these same commands repeat as buttons in the tool bar or as menu options at 

the top of the page. Additional commands available in the tool bar and menu include: 

Print – This allows the selection of various reports and results tables for hard-copy printing. 

Note: many of the tables are wide and print better in landscape mode. 

Export to Table – This allows whichever table is displayed in the project box to exported as 

either a Table Export in *.html format or a comma and space delimited text file suitable for 

importing into a spreadsheet program such as Microsoft ExcelTM. The export to the comma 

delimited export is very useful in the event you wish to sort, compare, or process the results 

in ways beyond those available within DRAS. 

Edit Customer COCs and DAFs – This allows the creation of and management of a 

database of chemicals or elements not preloaded in DRAS (See Section 5.4). Table entries 

can be made for the same physical, chemical, biological, and toxicological parameters 

entered for the DRAS default elements and chemicals. Dilution-Attenuation Factors (DAFs), 

a parameter relating leachate concentrations in the landfill or surface impoundment to 

groundwater concentrations at a nearby residential supply well, can be entered on a 

separate line. DRAS can only evaluate one constant DAF for a constituent entered in the 

customer database. This DAF will be used for all entered concentrations. To avoid run-time 

errors, please enter estimated DAFs for both landfill and surface impoundments for each 

unique constituent added. Note: this function is not operational in all installations at this 

time. In the event this function does not work on your computer, try installing DRAS on a 

different computer or choose a surrogate element or chemical (one you were not planning 

on including in your analysis) and modifying the physical, chemical, biological, and 

toxicological parameters in the table in DRAS window Steps 4 & 5 while noting your change. 

Analysis – This option lets you switch views between facility information, chemical data 

entry, and results screens. Note: the links to the Chemical Properties Database and the 

Show Delisting Level Analysis are not operational at this time. Show Delisting Level 

Analysis is meant to allow the calculation of delisting levels using only facility and target risk 

information for the purposes of conveying target data quality objectives at the outset of a 

project. EPA will attempt to restore these functions in the future. All chemical properties 

entered in the default database can be viewed in DRAS window Steps 4 & 5 once that 

element or chemical has been added to the project-specific list. All of these values can also 

be viewed along with references in Appendix A1 of the DTSD. Target data quality 

concentrations must be generated by selecting all of the elements and chemicals of concern 

and running DRAS to obtain maximum allowable total and TCLP concentrations. 

Window - This option lets you switch views between facility information, chemical data 

entry, and results screens but includes links to more of the individual results screens. Note: 

the link to the Chemical Properties Database is not operational at this time. All chemical 

properties entered in the default database can be viewed in DRAS window Steps 4 & 5 once 
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that element or chemical has been added to the project-specific list. All of these values can 

also be viewed along with references in Appendix A1 of the DTSD. 

DRAS v.3.1 Help – This command is reserved for a help, topics, index, and search-style 

help function which is not currently operational. Please refer to this guide, the DTSD, or the 

Agency’s contact for DRAS for assistance. The current Agency contact for DRAS is Todd 

Ramaly, EPA Region 5, and can be reached at 312-353-9317 or ramaly.todd@epa.gov. 

5.3 Steps 1-3 – Entering Facility Information 

The following screenshot shows the first data entry window. Step 1 includes fields for 

entering the project filename, petitioner, location, EPA Region, waste code, waste 

description, and pertinent dates. There is also a User Comment box where detailed 

comments about the run can be entered. This is helpful if the user wishes to run the project 

multiple times with varying inputs and differentiate one run from another. 

Step 2 – Waste Management Unit and Risk/HQ Information – is where the user specifies the 

following input: 

Waste Management Unit Type - Landfill for non-liquid wastes or Surface Impoundment

for liquid wastes; 

Waste Volume – This is the value for waste generated annually for continually generated 

wastes or one total volume for one-time projects like remediation. For landfills, please enter 

the annual volume in cubic yards. For surface impoundments, please enter the total volume 

of liquid in the surface impoundment in cubic meters (typical operating capacity). 

Flow Rate of Liquid – This applies to evaluations of surface impoundments only and must 

be set to the expected flowrate of liquid into the surface impoundment in cubic meters per 

year. 

Waste Management Unit Active Life – The default values are 20 years for landfills and 50 

years for surface impoundments. 

Target risk and target hazard quotient – The target risks and hazards are obtained from 

your delisting regulatory authority. 
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This Step also allows you to choose between a One Year Batch delisting, typical for a 

remediation waste scenario or a Multiple Year Batch where the facility plans on generating 

the waste indefinitely. 

 

On some systems, you may not be able to see the entire screen, including important 

commands at the bottom of the window. By selecting the Windows button that allows 

multiple window pane display (between the “minimize” button and the “close” “x” button on 

the menu bar above) the Steps 1-3 window refreshes with a scroll bar on the right. Use the 

scroll bar to move to the bottom of the window where you can now choose from the Step 3

options. The following screen shows the bottom of the Steps 1-3 window. 

Step 3 – The following four commands are presented under Step 3 – Update Information: 

Update Information – This locks in all entries or modifications made in steps 1 & 2. 

Cancel Changes – This clears all modifications to steps 1 & 2. 

Calculate Delisting Levels – This feature generates a concise list of maximum allowable 

concentrations for both total concentrations and leachate concentrations so that “practical 

quantitation limits” (PQLs – the concentrations at which selected laboratory methods are 

sensitive to the tested constituents) could be confirmed as adequate for comparison to the 
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DRAS maximum allowable concentrations. This feature is not currently working as 

intended. EPA recommends that waste constituents be entered in steps 4&5 and that the 

DRAS analysis be fully run to generate maximum allowable concentrations. The existing 

DRAS project named example.drs can be used to prepare provisional delisting levels for use 

as PQLs. The project example.drs has all chemicals in the DRAS database already 

selected so the user need only reenter the facility name, annual volume, and target risk and 

target hazard in order to quickly run the project. “Dummy” values for TCLP and total 

concentrations are also pre-loaded into example.drs. Even though the concentrations are 

not needed in determining maximum allowable delisting levels (for use as PQLs in this case) 

DRAS will not run without concentrations entered. Example.drs can be renamed to match 

your project. 

To Steps 4&5 – This option moves data entry to the Steps 4&5 window where individual 

waste constituents are selected and concentrations are entered. Note: This command will 

not be available unless all mandatory fields, marked with a red asterisk, are completed. 

5.4 Steps 4&5 – Selecting Chemicals of Concern 

Step 4 includes a table where individual waste constituents are selected for evaluation. By 

clicking in the Chemical Name or CAS Number fields, a drop-down table can be opened 

revealing all of the chemicals or elements available in the DRAS default database arranged 

in alphabetical order. Waste constituents are added to the project-specific Step 4 table by 

scrolling down and clicking on a particular constituent. The user can also begin typing a 

constituent name or CAS number and if a default constituent matches the entry, the dropdown table will advance to the matching constituent. 

Once added to the project-specific analysis table, the user must enter a concentration or 

detection level (in the case of non-detects) for both the total concentration and the leachate 

concentration. Leachate concentrations are typically obtained from the Toxicity 

Characteristic Leachate Procedure (TCLP) although other tests may apply depending upon 

the delisting regulatory authority’s requirements. A non-zero concentration must be entered 

for both types. If you wish to run the analysis with incomplete data, for example to see if a 

waste will pass based on existing data, EPA recommends that you enter a dummy value so 

that the program will run. The dummy value can be an extremely low detection level so that 

the estimated risk or hazard doesn’t skew the results. 

To record a non-detected result, enter the detection limit and select the “detection limit” box. 

Risks will be aggregated in two ways. One includes risks generated only from detected 

concentrations and another includes risks generated from both detected concentrations and 

a fraction (50%) of the detection limits from non-detected constituents. 
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Modifying physical, chemical, biological, and toxicological parameters: To modify any 

parameter (for example, to incorporate an updated cancer slope factor), the user can scroll 

across the line for a constituent by using the left and right cursor keys and typing in the new 

value. Any modifications to the default database will be documented in a particular output 

table. 

Evaluating waste constituents not available in the default database: In the event that the 

user wishes to evaluate a waste constituent that is not among those pre-loaded in the DRAS 

database, there are two ways to perform this evaluation. 

First, a customer-generated separate database for unique chemical entries can be prepared 

by the user. The menu item Edit Customer COCs and DAFs from the Edit menu. Table 

entries can be made for all of the same physical, chemical, biological, and toxicological 

parameters entered for the DRAS default elements and chemicals. DAFs, a parameter 

relating leachate concentrations in the landfill or surface impoundment to groundwater 

concentrations at a nearby residential supply well, can be entered on a separate line. The 

DRAS can only evaluate one constant DAF for a constituent entered in the customer 

database. This DAF will be used for all entered concentrations. To avoid run-time errors, 

please enter estimated DAFs for both landfill and surface impoundments for each unique 

constituent added. 
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Instructions for adding a new COC: 

1. From the Main Screen, Click on Customer COCs and DAF under the Edit menu. 

This should bring up the Customer COC and DAF Screen (Fig 1). 

 Figure 1 

2. COC properties are entered in the top half of this window and DAF information is 

entered in the bottom half. 
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3. Click on the Chemical Name cell in the top window and enter the first COC: for 

example - HGLTEMP1 (Figure 2). After entering the Chemical Name, Click on the 

cell to the right (below CAS). The screen display would now be similar to Fig 2. 

 Figure 2
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4. Enter the values for CAS ID and other properties. Once all values have been 

entered, click on the row below (Colored in blue). This should update the COC 

properties. Once the database is updated, the pencil icon will change to a black 

arrow. 
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5. Now, click on the DAF window in the lower-half and enter CAS Number and 

respective DAFs. After entering all the data, click on the blue row below to update the 

database. Once the database is updated, the pencil icon will change to a black 

arrow. 
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6. To access this COC from the Site COCs screen, click on the drop down at the 

bottom and select the Customer option. Now, HGLTEMP1 can be added to the 

project database. 

Note: The Customer Database function is not operational in all installations at this time. If it 

does not work on your installation, please try installing DRAS on a different system or use 

the second approach to evaluating a non-default waste constituent as described in the next 

paragraph. 

A waste constituent not already included in the default DRAS database can also be added 

by selecting a DRAS constituent the user specifically does not need for the project to serve 

as a surrogate for analysis. Scroll to the right to enter all the physical, chemical, biological, 

and toxicological parameters to match the new chemical or element. Choose an organic 

chemical, or one for which the DAFs are not “TCLP dependent” for the surrogate. The user 

must keep a separate record documenting that the chemical selected is actually a surrogate 

for another. 

The remaining commands under Step 5 – Update Chemicals of Concern and Run DRAS

are: 

Cancel Changes – This will remove any modifications made since the last update. 
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Update Site COCs – This will save all changes and entered data in Step 4. Users should 

update periodically while adding many waste constituents in order to minimize the loss of 

data if the program unexpectedly quits. 

Delete COC – This will delete a selected waste constituent only if the line corresponding to it 

is highlighted by clicking on the box to the left of the Chemical Name.

Back to Steps 1-3 – This will return the user to Steps 1-3, Delisting Petitioner Information, 

Waste Management Unit and Risk/HQ Information, and Update Information.

Run DRAS – This will run the DRAS analysis, providing both a forward estimate of risk and 

hazard based on the concentrations of waste constituents entered and a list of maximum 

allowable concentrations back-calculated from the target risk and hazard settings
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6 Results 

The following tables will open upon a successful DRAS run with each available for viewing, 

printing, or export: To return to Steps 1-3 or Steps 4&5 from the results screens, click Close 

Results Screens under the Windows menu at the top of the page. 

List of Customer COCs – This is a list of all customer COCs selected for analysis including 

all physical, chemical, biological, and toxicological data entered. 

List of COCs with Altered Chemical Properties – This is a list of all default DRAS COCs 

selected for analysis where the user has altered any of the physical, chemical, biological, 

and toxicological data. This table will identify each parameter, units, the original value, and 

the new value. 

Limiting Pathways – This table summarizes the most sensitive pathway for each constituent 

for both ground water pathways (evaluated as leachate) and surface pathways (evaluated 

as total concentrations). 

Groundwater Pathway Hazard Quotient – This displays the estimated hazard quotient via 

ground water for each waste constituent by pathway and summed by constituent and 

pathway. 

Groundwater Pathway Risk – This displays the estimated excess cancer risk via ground 

water posed by each waste constituent and summed by constituent and pathway. 

Maximum Allowable TCLP Concentration – Groundwater Exposure Pathway – This table 

displays the maximum allowable receptor concentration for a number of ground water 

exposure pathways based on target risk and hazard settings. The minimum value of these 

concentrations and the Safe Drinking Water Act MCL is converted into a maximum 

allowable waste leachate concentration based on the DAFs that apply. 

Surface Pathway Hazard Quotient – This displays the estimated hazard quotient via surface 

pathways for each waste constituent by pathway and summed by constituent and pathway. 

Surface Pathway Risk – This displays the estimated excess cancer risk via surface 

pathways posed by each waste constituent and summed by constituent and pathway. 

Maximum Allowable Total Concentrations – Surface Exposure Pathway – This table 

displays the maximum allowable total concentration for a number of surface exposure 

pathways based on the target risk and hazard settings. The least of these concentrations is 

selected as the overall maximum allowable concentration. 

Aggregate Risk and Hazard Quotient Results – All excess carcinogenic risks for both 

detected values only and a combination of detected values and a fraction (50%) of the 

detection level for non-detected constituents are aggregated here. All hazard quotients for 
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both detected values only and a combination of detected values and a fraction (50%) of the 

detection level for non-detected constituents are aggregated here into a hazard index. Note: 

If the hazard index exceeds the target hazard set by the delisting regulatory authority, EPA 

recommends that the constituents may be evaluated and split by target organ (see DTSD 

Appendix A-4) before drawing a conclusion about exceeding the target hazard. 

Toxicity Characteristic, Soil Saturation, and Ecological Values – This table identifies waste 

concentrations that exceed toxicity characteristic concentrations, waste concentrations that 

exceed soil saturation values (a condition that cannot be evaluated properly by the fate and 

transport models used in DRAS), and waste concentrations that result in surface water 

concentrations (from uncontrolled run-off at the waste management unit) that exceed 

surface water quality criteria. 

Pathways Exceeding the Delisting Limits – This is a concise summary of only those 

evaluated constituents that exceed the maximum allowable concentrations based on target 

risk and hazard settings.