Now Includes:
- 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)
Page
Contents
Click on the figures below
to see a screen capture of modeling results.
Well Capture
Zones
|
Contaminant
Plume
|
Concentration
vs. Time
|
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.
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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 |
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to Page Contents
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.
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Requirements
- PC Pentium (100 MHz)
- 32 Mb RAM
- 25 Mb free disk space
- SVGA display minimum
- Windows 9x/NT/2000/XP or higher
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