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<< Click to Display Table of Contents >> Description |
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In this example, Monte Carlo simulation will be used to examine the effect of uncertainty in the service life of a Primary Leachate Collection system. The landfill from example 15 will be used, except the time that the Primary Leachate Collection system begins to fail will vary between 20 and 50 years with a mode of 25 years. Case 15 should be reviewed prior to reading this example, where the implementation of the Variable Properties and Passive Sink special features are described in detail.
The parameters for this example are the same as in Case 15, except for the addition of the Monte Carlo parameters.
Following are the parameters used in this example:
Property |
Symbol |
Value |
Units |
Darcy Velocity |
va |
variable |
m/a |
Sink Outflow Velocity |
vs |
variable |
m/a |
Diffusion Coefficient |
D |
0.02 |
m2/a |
Dispersivity |
|
0.4 |
m |
Distribution Coefficient |
Kd |
0.0 |
cm3/g |
Soil Porosity |
n |
0.4 |
- |
Granular Layer Porosity |
n |
0.3 |
- |
Dry Density |
|
1.5 |
g/cm3 |
Layer 1 Thickness |
H |
1 |
m |
Layer 2 Thickness |
H |
0.3 |
m |
Layer 3 Thickness |
H |
2 |
m |
Source Concentration |
c0 |
1000 |
mg/L |
Ref. Height of Leachate |
Hr |
7.5 |
m |
Vol. of Leachate Collected |
Qc |
variable |
m/a |
Landfill Length |
L |
200 |
m |
Landfill Width |
W |
1 |
m |
Aquifer Thickness |
h |
1 |
m |
Aquifer Porosity |
n |
0.3 |
- |
Aquifer Outflow Velocity |
vb |
4 |
m/a |
Minimum Failure Start Time |
|
20 |
a |
Modal Failure Start Time |
|
25 |
a |
Maximum Failure Start Time |
|
50 |
a |
This example is for a hypothetical landfill and is used to illustrate how to prepare an input file and run an analysis using the Variable Properties and Passive Sink option. The example is not a prescription for modeling contaminant migration during operation of a landfill. Each landfill has its own unique characteristics and no general prescription can be made. These options should only by used by someone with the hydrogeologic and engineering background necessary to appreciate the subtleties associated with the physical situation and the steps necessary for appropriate modeling of this physical situation. This option should not be used for an actual project of importance without the guidance of the program developers.
The use of the Monte Carlo simulation feature for the variation of Variable Properties time periods should be done in consultation with the program developers, since it requires a very thorough knowledge of the program.