PNNL-SA-32281
Written by: John W. Buck

Prepared for the U.S. Department of Energy

Pacific Northwest National Laboratory
Operated by the U.S. Department of Energy
By Battelle



Requirements for the MEPAS Software

1.0 Introduction

The Multimedia Environmental Pollutant Assessment System (MEPAS) software allows users to evaluate chronic human health and environmental impacts resulting from planned and unplanned environmental releases. This document contains the requirements for this system and can be used by software engineers and testers to ensure the system functions properly. A test plan with specific test cases will be developed from the test plan to ensure that the product meets the needs of the client(s) and users.

2.0 Purpose of MEPAS Software

The purpose of the MEPAS software is to evaluate chronic human health and environmental impacts resulting from planned and unplanned environmental releases. The MEPAS software consist of physics-based codes that simulate the release, fate, and transport of chemical and radioactive contaminants in the air, soil, ground water, and surface water media and evaluates their potential to affect human health. The MEPAS software utilizes sophisticated computer codes to quickly and easily assess impacts from activities that could impact human health and the environment. MEPAS operates under the Framework for Risk Analysis in Multimedia Environmental Systems (FRAMES), which allows other codes to be integrated with MEPAS codes. Whelan et al. (1987) and Whelan et al. (1992) are general references on the MEPAS software.

3.0 Summary of Requirements for the MEPAS Software

This section provides an overall summary of the requirements for the MEPAS software along with the specific requirements for its interface with FRAMES. Detailed input, output, and scientific requirements are described in the following sections.

The MEPAS software will:

  1. operate under the FRAMES software platform and have input and output data files that conform to data specifications defined by the FRAMES software platform
  2. The MEPAS codes will provide users with an ABOUT Tab to inform users of the title, version # and general description of code.
  3. provide users with Windows-based user interfaces with on-line help addressing the input data required to run the MEPAS codes
  4. provide users with source, vadose, aquifer, surface water, air, exposure, intake, and impact Modules
  5. provide users with four primary types of results: contaminant mass fluxes, contaminant concentrations, dose at specified receptor points , and impacts at specified receptor points
  6. provide users with list files that echo input data and intermediate results from each MEPAS model.
4.0 Input Requirements for the MEPAS Software

The user enters the input data required for the different MEPAS modules via the module user interface (MUI). The MUI allows the user to define the source problem and associated data. The specific requirements for each individual MEPAS MUI are provided in separate documents for the specific MEPAS module (source, vadose, aquifer, surface water, air, exposure, intake, and impact). The reader is referred to these specific requirements documents to understand the input requirements of each MUI. This document provides general requirements for the MUIs associated with the MEPAS software modules.

There are some general requirements associated with the MUI, which are

  1. The MUI will operate in Windows 95 and will have a standard Windows look and feel.
  2. The MUI will have on-line help in an HTML format that provides users with an easy-to-understand description of all input parameters required by the MUI.
  3. The MUI will provide users with a choice of units for all input parameters having dimensions associated with them.
  4. The MUI will include a reference feature in which the source of the specified value for each input item can be referenced if the user desires.
  5. The MUI will provide an ABOUT tab to inform the user of the title, version # and general description of code.
  6. The MUI will show the range of values allowed for each input data item, when the cursor is positioned on that item, as a scrolling message at the bottom of the screen.
  7. When an out-of-range value is entered in a field, the MUI will indicate this by a red background in the input field and an error message in addition to the allowed range message. Data input values within range are shown with a green field background.
All MEPAS modules are required to conform to the FRAMES data file specifications that are defined in Whelan et al. (1997) as revised. The MEPAS modules will receive input by requesting input from the user via the MUI, reading from the Global Input Data (GID) file, and reading the appropriate FRAMES data file.  The appropriate files include: Air Flux File (AFF), Water Flux File (WFF), Soil Concentration File (SCF), Atmospheric Transport Output (ATO), Water Concentration File (WCF), Exposure Pathway File (EPF), Receptor Intake File (RIF), and Health Impacts File (HIF). Any special databases required by a MEPAS module are accessed through that module MUI.

5.0 Output Requirements for the MEPAS Software

The MEPAS software is required to have four primary output results

  1. time-varying, contaminant mass fluxes from a source or transport modules
  2. time-varying, contaminant concentrations in the environment from transport modules
  3. time-varying, concentration in the exposure media from exposure pathway modules
  4. time-varying, health impacts to humans at specified receptor points.
There are two types of contaminant mass flux output from the MEPAS source module.  The output is either time-varying contaminant particle and gaseous emission rates (AFF) or time-varying contaminant infiltration and overland runoff contaminant mass flux rates (WFF). The MEPAS Vadose Zone Module also produces time varying contaminant mass fluxes for waterborne transport calculations. There are two types of contaminant concentration output from the MEPAS transport modules (air, aquifer, and surface water): time-varying contaminant air concentrations (ATO) and time-varying contaminant water concentrations (WCF). The MEPAS Exposure Module produces time varying concentrations at the receptor point (EPF). The MEPAS Intake Module produces time-varying doses to receptors (RIF). The MEPAS Impact Module produces time-varying impacts to receptors (HIF).

The MEPAS modules are required to produce an intermediate file that provides the user an echo of the input data to the model and the results of intermediate calculations that support the output from the module. These files are not required by the FRAMES data file specifications, and they are not meant to be FRAMES files. The files are useful for debugging and confirming results from the MEPAS modules.

MEPAS module primary results are output in the FRAMES data file format, which allows these results to be used by the FRAMES Viewer and Sensitivity/Uncertainty Modules, as well as other module in FRAMES. This allows the user to view each of the MEPAS output files and conduct sensitivity and uncertainty analyses.

6.0 Scientific Requirements for the MEPAS Software

Scientific requirements for the MEPAS system are

  1. Mass balance must be maintained throughout the MEPAS system of modules.
  2. Each module must apply technically defensible, standard scientific techniques to perform its function.
Each of the MEPAS modules has a mathematical formulation document that provides the scientific requirements for that module. The reader is referred to the MEPAS web site (http://mepas.pnl.gov/earth/mepasmain.html) to identify the appropriate document for the specific module or to Section 8 of this report to the specific mathematical formulation document of interest.

7.0 Recommendations

The following is a list of recommendations on future additions and updates to this module. This list is not meant to be all-inclusive but modifications that have been suggested by user and developers. This list can be used to help prioritize modifications to this and other modules based on the overall strategy of the software system.

Recommended additions and modifications to this module are:

  1. develop demonstration version of MEPAS 4.1 for downloading from the Internet
  2. add indoor air model to evaluate volatile organic compounds emissions
  3. multiple aquifer modules in a scenario
  4. add a population impacts module
  5. link surface water modules to other surface water modules
  6. complete testing of MEPAS wetlands module
8.0 References

Whelan, G., D. L. Strenge, J. G. Droppo, Jr., and B. L. Steelman. 1987. The Remedial Action Priority System (RAPS): Mathematical Formulations. PNL-6200, Pacific Northwest Laboratory, Richland, Washington.

Whelan, G., J. W. Buck, D. L. Strenge, J. G. Droppo, Jr., and B. L. Hoopes. 1992. "Overview of the Multimedia Environmental Pollutant Assessment System (MEPAS)." Hazardous Waste & Hazardous Materials, Vol. 9, No. 2, pp. 191-208.

Whelan G., K. J. Castleton, J. W. Buck, G. M. Gelston, B. L. Hoopes, M. A. Pelton, D. L. Strenge, and R. N Kickert. 1997. Concepts of a Framework for Risk Analysis in Multimedia Environmental Systems (FRAMES). PNNL-11748, Pacific Northwest National Laboratory, Richland, Washington.

MEPAS Modules Mathematical Formulation Documents

Streile, G. P., K. D. Shields, J. L. Stroh, L. M. Bagaasen, G. Whelan, J. P. McDonald, J. G. Droppo, and J. W. Buck. 1996. Multimedia Environmental Pollutant Assessment System (MEPAS): Source Term Formulations. PNL-11248. Pacific Northwest National Laboratory, Richland, Washington.

Droppo, J. G., Jr. and J. W. Buck. 1996. Multimedia Environmental Pollutant Assessment System (MEPAS): Atmospheric Pathway Formulations. PNL-11080. Pacific Northwest National Laboratory, Richland, Washington.

Whelan, G., J. P. McDonald, and C. Sato. 1996. Multimedia Environmental Pollutant Assessment System (MEPAS): Groundwater Pathway Formulations. PNL-10907. Pacific Northwest National Laboratory, Richland, Washington.

Whelan, G. and J. P. McDonald. 1996. Multimedia Environmental Pollutant Assessment System (MEPAS): Riverine Pathway Formulations. PNNL-11176. Pacific Northwest National Laboratory, Richland, Washington.

Strenge, D. L. and P. J. Chamberlain II. 1995. Multimedia Environmental Pollutant Assessment System (MEPAS): Exposure Pathway and Human Health Impact Assessment Models. PNL-10523. Pacific Northwest Laboratory, Richland, Washington.

Droppo, J. G., Jr., G. Whelan, J. W. Buck, D. L. Strenge, B. L. Hoopes, and M. B. Walter. 1989. Supplemental Mathematical Formulations: The Multimedia Environmental Pollutant Assessment System (MEPAS). PNL-7201, Pacific Northwest Laboratory, Richland, Washington.