Environmental Engineering Reference
In-Depth Information
Probability
Consequence
W A = A works
Alternative A:
conventional
pump and treat
0.8
-$20 mm + Δ c test
E ( C ) = -$24 mm + Δ c test
Successful
pilot-test
result, S
0.2
-$40 mm + Δ c test
F A = A fails
W B = B works
0.89
-$15 mm + Δ c test
Alternative B:
innovative
in situ treatment
0.11
-$35 mm + Δ c test
F B = B fails
Probability
Consequence
W A = A works
Alternative A:
conventional
pump and treat
0.8
-$20 mm + Δ c test
E ( C ) = -$24 mm + Δ c test
Questionable
pilot-test
result, Q
0.2
-$40 mm + Δ c test
F A = A fails
W B = B works
0.43
-$15 mm + Δ c test
E ( C | Q ) = -15*0.43 + -35*0.57 + Δ c test = -$26 mm + Δ c test
Alternative B:
innovative
in situ treatment
0.57
-$35 mm + Δ c test
F B = B fails
Probability
Consequence
W A = A works
Alternative A:
conventional
pump and treat
0.8
-$20 mm + Δ c test
E ( C ) = -$24 mm + Δ c test
Unsuccessful
pilot-test
result, U
0.2
-$40 mm + Δ c test
F A = A fails
W B = B works
0.07
-$15 mm + Δ c test
E ( C | U ) = -15*0.07 + -35*0.93 + Δ c test = -$34 mm + Δ c test
Alternative B:
innovative
in situ treatment
0.93
-$35 mm + Δ c test
F B = B fails
Figure 13.5 Decision trees for contaminated lagoon with different possible pilot-test results.
The Value of Information for the pilot test can then be assessed using the decision tree
in Figure 13.6 ; this step is referred to as a Preposterior decision since it is made before
additional information is obtained by considering all possible outcomes for the additional
information. The value of information for this pilot test is the value of ∆ c test such that
$
21
MM
+∆=−
c
$
24
MM
,
or ∆=−
c
$
3
MM
.
This value provides guidance on
test
test
 
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