| NAS - data loading
|
| • Data must be entered
manually. |
|
| NAS - graphic loading
|
| • Not applicable. Graphical
display is created within the program. |
|
| NAS - logical flow
|
| • Step-by-step windows
guide the user through data entry, including source data, water
chemistry, and site information. |
| • User can switch from
user input to graphical interface to display data and results. |
|
| NAS - expert knowledge
|
| • Extensive, site-specific
background data are required to enter all the necessary parameters
for the model to work |
| • Understanding of water
chemistry and how the analytical parameters relate to natural attenuation
is recommended. |
|
| NAS - functionality
|
| • Can be used to model
natural attenuation for both chlorinated solvents and petroleum
products. |
| • Separate windows are
used to enter model parameters. The user can switch between the
data entry windows and graphical interfaces to iteratively change
input parameters and view model results. |
| • Detailed information
on water chemistry for the site must be available for the model
to work. The program does not provide default values for missing
information, so the user must have expert knowledge about the average
values. |
| • User can enter regulatory
cleanup values and a downgradient point of compliance; the model
will calculate the amount of time required for a source to decay
until the plume concentrations are below regulatory cleanup levels
at the compliance point. The program displays this information in
a tabular and graphical format. |
| • The user can provide
a source term that consists of a nonaqueous phase liquid (NAPL).
|
| • A numerical model
(SEAM3D) is incorporated in NAS to estimate the Time of REmediation
(TOR) for the plume. It should be noted, however, thatthe parameter
information and observed data can only be specified along the plume
centerline (i.e., in one dimension). |
| • The user can create
custom reports showing all user input data and model results. |
|
| NAS - new or updated features |
| The most recent update to NAS is Version 2.2.0, released on January 2, 2006. Some of the revisions that were incorporated as part of this update include: |
| • Upgraded SEAM3D to the latest Fortran version: reduced time of remediation (TOR) simulation times. |
| • Modified user interface during TOR simulations to improve multi-tasking with other Windows programs while TOR simulations are running. |
| • New contaminants: expanded to include chlorinated ethanes, chlorinated methanes, and chlorinated benzenes, and any other user-defined contaminants that may be subject to microbially mediated transformations (such as heavy metals and radioisotopes). Included is the capability to model co-mingled plumes, with constituents from multiple contaminant categories. |
| • NAS can now model sites with existing or proposed pumping wells based on user-specified site hydrogeologic and source data. This capability enables comparison of remediation timeframe estimates between MNA and pump-and-treat remedial actions. |
| • NAS also includes expanded analysis tools for improved performance assessment. Sustainability of natural attenuation processes over time may also be assessed. Users may analyze contaminant concentration measured at the site and redox indicator data to allow for comparisons of NAS-predicted versus observed trends. The user also can monitor changes in natural attenuation capacities and redox conditions over time. |
| |
| NAS - documentation
|
| • The users manual explains
the windows and user-required inputs; however, it does not provide
any background information about the parameters and why they are
used. |
| • No help files; user
must refer to the users manual. |
| • A user-group e-mail
list is provided on the website. The user group is a resource for
help with troubleshooting problems and asking questions. |
|
| NAS - output |
| • Limited output capabilities.
NAS provides a report of user data and modeled outputs. |
| |
| NAS - technical support |
| •The homepage for NAS is now at http://www.nas.cee.vt.edu/index.php, and the program can be downloaded from the site. |
| •Technical support for NAS is provided through an e-mail listserv address provided on the software home page or through the e-mail address NAS_Tech_Support@vt.edu. Training classes have been offered in various regions throughout the year, although the current list is for past classes. |
| |
| NAS - sources
|
| • Version 1.30 downloaded
November 17, 2004. |
| • Users Guide. |
| • Website offers tour
of software via a PowerPoint presentation. |
| • Examples. |
|
NAS
Overview 