- Multi-Site Rate-Limited Desorption
- Sequential Decay (PCE=>TCE=>DCE=>VC)
- Instantaneous BTEX Bio with Multiple Electron Acceptors
- Kenetic BTEX Bio with Multiple Electron Acceptors
- Plume Generator Which Respects Measured Concentrations
- Expert Help System (tables and references for all input parameters)
Description
Click on the figures below to see a screen capture of modeling results.
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The RBCA Tier 2 Analyzer utilizes a innovative analytical flow solution for fast and easy modeling of complex groundwater flow systems, it provides a rigorous treatment of the many complex reactions and processes involved with the biodegradation of contaminated groundwater. These two features make it the ideal software package for applications including:
- Simulating natural attenuation of contaminated groundwater,
- Evaluating groundwater pump-and-treat remediation systems, or
- Predicting downstream impacts for risk assessment studies
Expert System Advantages
It is a well-known fact that the two biggest challenges
of modeling natural attenuation processes are:
- Finding reliable references for the many different input parameters required by the model; and
- Waiting for the simulation to finish calculating
The RBCA Tier 2 Analyzer addresses both of these problems by providing an on-line expert system with published parameter values and references for many different soil conditions and common chemicals of concern. In addition, the RBCA Tier 2 Analyzer uses a powerful and innovative solution method that allows you to solve complex models involving biodegradation of multiple chemical species in a matter of minutes! Try that with RT3D and you could be waiting for hours. Imagine the time you could save on just your first project alone!!
The Flow Model
The analytical flow model allows the user to account for
complex boundary conditions representing pumping wells
and injection wells, flow boundaries, rivers and lakes
with complex geometries, and regional hydraulic
gradients. The analytical flow model is based on the
super-position of the Dupuit-Forchheimer solution for
flow to one or more wells with the effects of a regional
hydraulic gradient (Bear, J. 1979. Hydraulics of
Groundwater. New York: McGraw-Hill). This
analytical solution is capable of simulating complex
model boundaries and 'leaky' boundary conditions by using
an iterative solution that dynamically links the
hydraulic impacts of the wells and/or water body(s) on
the aquifer. Modeling results include heads, velocities
and pathlines for determining well capture zones and
groundwater travel times.
The Plume Generator
The initial condition plume generator provides the user
with the capability of generating physically realistic
distributions of contaminant plumes and electron
acceptors using real field measurements. The
automatic plume generation program utilizes the
super-position of multiple Gaussian plumes along a
user-specified centerline. This interpolation
technique is ideally suited for sparse, highly-variable
data such as groundwater contamination measurements, and
it ensures a concentration distribution consistent with
observed groundwater flow patterns. Initial
concentration distributions can also be imported from
Surfer Grid (.grd) files.
The Transport Model
The RBCA Tier 2 Analyzer solves for advective-dispersive
contaminant transport with equilibrium/non-equilibrium
sorption and complex decay reactions. Five
different contaminant transport scenarios are provided:
- Single constituent
- Sequential decay of PCE due to reductive dechlorination
- BTEX biodegradation (instantaneous decay with a single electron acceptor)
- BTEX biodegradation (instantaneous decay with multiple electron acceptors)
- BTEX biodegradation (kinetic-limited decay with multiple electron acceptors)
The RBCA Tier 2 Analyzer is also the first commercially-available model to incorporate the physics of multi-site, rate-limited partitioning of chemical mass between soil and groundwater. Rate-limited desorption (RLD) of organic contaminants is the most significant limitation of pump-and-treat groundwater remediation systems. The effects of RLD are seen in the extended periods of low mass removal rates which were not predicted by models using local equilibrium sorption/desorption assumptions. Now, for the first time, you have a modeling software package that allows you to account for and predict the effects of RLD desorption on groundwater extraction systems.
The RBCA Tier 2 Analyzer uses Eulerian-Lagrangian solution technique to solve the governing equation of solute transport. This technique utilizes the Method of Characteristics (MOC) for solving the advective part of the equation, and it uses the Alternating Direction Implicit (ADI) method for solving the dispersive part of the equation. This combination of solution techniques ensures the best results in the shortest time by avoiding the numerical dispersion and small time steps often encountered by other numerical approaches.
Output Graphics
The RBCA Tier 2 Analyzer includes an impressive selection
of graphical capabilities for visualizing and
interpreting the modeling results. Output graphics
include:
- Contouring and color shading of head and concentration values
- Flow pathlines and velocity vectors
- Concentration time-series graphs for any location in the model domain
Full color, high-resolution graphics of all modeling results can be directed to any printer or plotter supported by Windows 9x/NT/2000/XP or higher.
Key Features
Plume Generator |
Transport Options |
Sorption Options |
Innovative Analytical Flow Model
The unique
analytical flow solution combines the time-saving
benefits of simple analytical solutions, with the
ability to simulate complex model geometries and
boundary conditions (pumping/injection wells,
rivers, lakes, recharge, no flow areas, etc.).
Automatic Plume Generator
The initial
condition plume generator uses real field data
and a specialized interpolation routine to
generate a physically realistic distribution of
measured groundwater concentrations at your
site. This distribution can be used as the
initial conditions for simulating biodegradation
of contaminated groundwater, or for designing a
groundwater extraction system.
Faster Contaminant Transport Solutions
The RBCA Tier 2 Analyzer uses a powerful solution
method for solving the governing equation of
solute transport. This innovative approach
eliminates the problems typically associated with
numerical dispersion and minimizes the long
computational times required for multi-species
reactive transport simulations. Now you can
solve complex models involving biodegradation of
multiple contaminants in just
minutes!
Rigorous Treatment of Contaminant Transport Reactions:
- Advective-dispersive transport with equilibrium/non-equilibrium sorption, multi-site, rate-limited desorption, and complex decay reactions
- Single or multiple contaminant species
- Sequential decay reactions (e.g. reductive dechlorination of PCE)
- Instantaneous or kinetic-limited BTEX biodegradation with single or multiple electron acceptors
Easy-To-Use Graphical Interface
The RBCA Tier 2 Analyzer comes with a
full-featured graphical interface for visualizing
all of the model input data and presenting the
results.
Output Graphics
The RBCA Tier 2 Analyzer includes an impressive
selection of graphical capabilities for
visualizing and interpreting the modeling
results. Output graphics include:
- Contouring and color shading of head and concentration values
- Flow pathlines and velocity vectors
- Concentration time-series graphs for any location in the model domain
- Animation of flow pathlines and contaminant plumes
Full color, high-resolution graphics of all modeling results can be directed to any printer or plotter supported by Windows 95/98/NT.
Expert System On-Line Help
The RBCA Tier 2 Analyzer includes a comprehensive
on-line help with published values for many of
the parameter values required by the model.
The on-line help also provides detailed
descriptions of the complex biodegradation and
sorption processes being simulated.
Click on the figures below to see screen captures from the RBCA Tier 2 Analyzer.
Example Help |
Model Grid |
Chain Decay Results |
Advantages Over BIOPLUME III and RT3D
Recent research [e.g., Zhang, W., E.J. Bouwer, and W.P. Ball. 1998.
"Bioavailability of hydrophobic organic contaminants: effects and
implications of sorption-related mass transfer on bioremediation." Ground
Water Monitoring & Remediation 18(1), 126-138] has shown that biodegradation is frequently controlled by rate-limited desorption (RLD) of contaminants from the soil. Therefore, it is critical for accurate assessment of natural attenuation that RLD be included in the model. Since BIOPLUME III does not handle rate-limited desorption, it cannot model the contaminant influent concentration "tailing" effects that typically occur in real-world remediation systems. RBCA Tier 2 Analyzer provides this capability.Numerous investigators [e.g., Haggerty, R., and S.M. Gorelick. 1995.
"Multiple-rate mass transfer for modeling diffusion and surface reactions in
media with pore-scale heterogeneity." Water Resources Research 31,
2383-2400] have shown in the last few years that multi-site RLD models (in
contrast to one-site models such as RT3D) most accurately reproduce tailing
effects.RBCA Tier 2 Analyzer greatly simplifies the specification of boundary and
inflow conditions by automatically defining concentrations at aquifer inflow
boundaries and river and lake inflow concentrations. This is especially
helpful with multi-constituent simulations such as PCE sequential decay and
BTEX biodegradation with multiple electron acceptors.RBCA Tier 2 Analyzer incorporates the automatic plume generator which can
generate not only initial-condition contaminant plumes but also initial
electron-acceptor (e.g., oxygen, nitrate, sulfate) concentration
distributions.The numerical flow code in BIOPLUME III is much more complicated to use
and slows down simulation times compared to the analytical flow techniques in RBCA Tier 2 Analyzer.In RBCA Tier 2 Analyzer lakes and rivers can easily be specified using the
graphical interface and the effects on the flow field can be instantaneously
viewed.Much larger transport time steps (and, therefore, greatly reduced run
times) can be used with RBCA Tier 2 Analyzer because it uses fully implicit
solutions of the biodegradation equations (BIOPLUME III uses stability-constrained, explicit solutions), the backward method of
characteristics (MOC) for advection, and the alternating direction implicit
(ADI) method for dispersion.The transport code in RBCA Tier 2 Analyzer runs much faster than the
BIOPLUME III code and is easier for results interpretation because BIOPLUME
tracks a large number of discrete particles to represent the plume.RBCA Tier 2 Analyzer offers a much more extensive on-line help system
that contains many tables of flow, transport, and sorption input parameter
values.
System Requirements
Requirements
- PC Pentium (100 MHz)
- 32 Mb RAM
- 25 Mb free disk space
- SVGA display minimum
- Windows 9x/NT/2000/XP or higher