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Page Title:
Table 1. Aggregated Sources of Uncertainty to be Evaluated for Their Relative Importance to Uncertainty in the Tiered Approac... |
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 Table 1
Aggregated Sources of Uncertainty to be Evaluated for Their Relative Importance to Uncertainty in the Tiered Approach to
Dredged Material Decision Making
Uncertainty
Ease with Which
Type of
Magnitude of
and/or
Uncertainty Can
Uncertainty2
Uncertainty4
Variability1
Be Quantified?3
Uncertainty Source
Tier I Evaluation
Identification of contaminants of concern (COCs)
u
Parameter
Difficult
NR
Sampling uncertainty
u
Parameter
Easy
Low
Spatial representativeness5
u,v
Parameter
Easy
Low
Analytical uncertainty
u
Parameter
Easy
Low
Dredged material physical and chemical characteristics
u,v
Parameter
Easy
Low
Description of dredging and disposal activities including quantity of material to be dredged
u
Scenario
Easy
Low
Selection of reference sediment
u,v
Model
Difficult
NR
Tier II Evaluation
Water Column Impact
u
Model
Easy
Moderate
Numerical mixing models
Benthic Impact
Theoretical bioaccumulation potential for nonpolar organics
u,v
Model
Easy
Moderate
u,v
Model
Easy
Moderate
Equilibrium sediment guidelines
Tier III Evaluation
Water Column Bioassay
u,v
Model
Easy
Low
Precision of bioassay
u,v
Model
Moderate
Moderate
Interpretation of bioassay
Sediment Bioassay
u,v
Model
Easy
Low
Precision of bioassay
u,v
Model
Easy
Moderate
Interpretation of bioassay
Benthic Bioaccumulation
u,v
Model
Easy
Moderate
Bioavailability from sediment
Trophic transfer
Fish
u,v
Model
Easy
High
u,v
Model
Moderate
High
Piscivorous birds
1
u = uncertainty (lack of knowledge), and v = variability (population heterogeneity).
2
See Chapter 1, "Uncertainty nomenclature," for explanation of each category of uncertainty.
3
Uncertainty that is difficult to quantify may take the longest to assess.
4
NR = not ranked because insufficient data are available to estimate magnitude of uncertainty; Low = mathematical effect is an order of magnitude or less; Moderate = one or two
orders of magnitude; High = mathematical effect could be several orders of magnitude; PS = project-specific; MS = model-specific (magnitude of uncertainty can span the full range).
5
Magnitude of uncertainty depends on sample size.
(Sheet 1 of 3)
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