Transcript No Slide Title

Modeling Natural Attenuation with
BIOSCREEN
GROUNDWATER
SERVICES, INC.
BIOSCREEN Natural Attenuation Model
Objectives

How Far Will
Plume Migrate?

How Long Will
Plume Be There?
?
?
Groundwater Transport Processes
Groundwater Transport Modeling
All groundwater transport models are based on the advectivedispersive-reactive equations.
rate of
change in
HC conc. at
any point
=
Transport at time t
advection only
net rate of
advective
transport to
that point
+
net rate of
dispersive
transport to
that point
Transport at time t
with dispersion
-
net rate of
degradation
at that point
Transport at time t
with dispersion
& degradation
Fate and Transport Modeling Options
GOAL: Predict steady-state NAF between source and receptor.
Types of
Models:
• 1-D vs. 2-D vs. 3-D Advection
• 1-D vs. 2-D vs. 3-D Dispersion
• Deterministic vs. Statistical
• Numerical vs. Analytical
• Transient vs. Steady State
• Constant Source vs. Changing Source
Air Force Natural Attenuation Initiative
Products

Technical Protocol

Field Data

Modeling Tools
Transport: Groundwater
in Source Zone
Groundwater at Receptor
Concentration at Downgradient
Distance x Away from Source
First-Order Decay
Constant
Conc (x) =
exp
{
x
2 x
[
(
1- 1+
1/ 2
)
Vs/R
]} [ ] [ ]
Retardation
Coefficient
Longitudinal
Dispersivity
Groundwater
Seepage
Velocity
4  x
Hydraulic
Conductivity
Vs =
Ki
ne
Groundwater
Source Width
and Depth
erf
Sw
4 y x
Sd
erf
4
z x
Error
Transverse Vertical
Function Dispersivity Dispersivity
Hydraulic
Gradient
Effective Soil
Porosity
Source Term Configuration
Location: Downstream of Affected Soil Zone
Concentration
Depth
BIOSCREEN Model: Other Features
 Single Vertical
Plane Source
 Superimposed Sources
(Connor et al., 1995)
Source 1
Source 2
Source 3
Where to Get BIOSCREEN
EPA Center for Subsurface Modeling
Support (R. S. Kerr Lab)
 Web:
http://www.epa.gov/ada/bioscreen.html
 Phone
(405) 436 8718