The content on this page is currently minimally managed and may be outdated..
The content on this page is currently minimally managed and may be outdated..
Environmental Protection Agency HSSM Overview  

The Hydrocarbon Spill Screening Model (HSSM) is intended to simulate releases of light nonaqueous phase liquids (LNAPLs) to the subsurface environment. The model is based on simplified conceptualizations of the flow and transport phenomena. The model consists of separate modules for LNAPL flow through the vadose zone, spreading in the capillary fringe, and transport of chemical constituents of the LNAPL in a water table aquifer.


HSSM Home Site
  • Visualization
  • Analytical Modeling
  • Input
  • Tabular File: *.dat
  • Graphical File: NA
  • Output
    • Tabular File: NA
    • Graphical File: *.bmp
    • Print Report: Yes
    • Chlorinated Solvents
    • Petroleum
    • Soil Sediment
    • Groundwater
    Technical Team Members
    • Hydrogeologist
    HSSM - data loading
    • Data must be entered manually.
    • As data are entered into the program through the Edit menu, they are checked to ensure that the data are within the parameters of the program. This feature can be turned off at the user's discretion.
    • HSSM uses a standard set of units; all data must be in these units for the program to output the proper information. The units are listed in Volume 1 of the manual under Section 4.6.2.
    • The users guide contains standard values for many of the parameters that must be entered for each of the unknown values. However, in some cases, the values are ranges, and the user needs to enter site-specific information.
    • Once the user starts entering data into the forms, the process cannot stop mid-form, without losing the data. The user may leave the form without saving any of the information entered.
    HSSM - graphic loading
    • Not applicable.
    HSSM - logical flow
    • Data must be entered through the Edit menu. Once entered, the information should be saved; the models are run through the Model menu. Once the models are run, graphs are drawn using the Graph menu.
    • The user must repeatedly refer to the users guide and appendices for values and units used when entering data.
    HSSM - expert knowledge
    • The program requires detailed knowledge of the hydrogeology of the site. Many parameters are specific to the equations used in the model. Certain parameters are listed in the users guide; however, they were developed from laboratory experiments under controlled conditions. Therefore, the listed parameters may not be representative of site conditions.
    • The user should have knowledge of hydrogeology to specify the parameter values required. Knowledge of the site hydrogeology is also important in interpreting the program output.
    HSSM - functionality
    • There are a large number of variables for this program. The user must know enough about the input variables to enter data in the proper units and in the proper location.
    • The user selects the model to run and follows on-screen instructions. The MS-DOS window stays open after the model has finished, so the user must close the window before proceeding.
    • To produce the graphs, the user clicks on the Graph menu and selects the graphs desired.
    HSSM - documentation
    • The users guide contains background mathematical information, instructions, definitions, and sample problems. It is written for use in the Windows 3.x environment, and the information on installation is out of date.
    • The first three sections of the Volume 1: Users Guide provides the theoretical basis for the model, but does not explain how to use the program. Directions for program use begin in Section 4.4.
    • Reading the manual requires some detailed knowledge of hydrogeologic properties. If the user does not know certain hydrologic equations or some variables in an equation, it is difficult to understand what should be entered in each window.
    HSSM - output
    • Output for HSSM is graphical. Graphs can be printed directly from the application.
    • Graphs can be copied directly using the Windows clipboard and pasted into another application, such as Microsoft Word. The graphs will be the same size as they appear on the user's screen when the user copies them. The text size is fixed. If the graph is full screen, the text will likely be too small to read after it is pasted into a Microsoft Word document.
    • The users guide provides the names of the output graphs, but does not offer graphic interpretation.
    • The tabular data are available in a number of files specific to the program. They can all be opened using Notepad and can then be printed.
    HSSM - sources
    • Version 3.11 downloaded November 23, 2004.
    • Volume 1: Users Guide.
    • Volume 2: Theoretical Background and Source Codes.
    • Help Menus.
    Note that this DST matrix is under active construction. Comments and suggestions about the structure
    or content of this website should be sent to Mike Adam .
    This web site contains technology information from private contractors and government agencies and is for informational purposes only. EPA cannot guarantee the accuracy or completeness of the data. Reference to any specific commercial product, process, or service, by trade name, trademark, manufacturer, or otherwise, does not constitute or imply the endorsement, recommendation, or favor of the United States Government.