Spatial Analysis and Decision Assistance
Decision Analysis
SADA was designed to provide a variety of summarization, visualization,
and modeling tools that aid in making informed decisions. Within that
design is a set of tools directly related to decision-making issues. These
tools are:
The cost/benefit and secondary sampling tools are discussed in detail
in separate pages. This page will concentrate on
decision scales and areas of concern.
Decision Scales
There are two scales for decision making in SADA: block and site. Given
a decision criteria, SADA can evaluate the implications for either framework.
Block Scale
Under the block scale, SADA compares the value of each block to the decision
criteria. If a given block fails this criteria, it must be remediated.
In other words, this action could be used if decision-makers do not want
any point on the site to exceed a particular value.
Site Scale
Under the site scale, SADA estimates the number and location of blocks
requiring remediation so that the representative site value is acceptable
in comparison to the decision criteria. In other words, this action could
be used if decision-makers do not want the average concentration of the
site to exceed a particular value.
Area of Concern
Given a cleanup goal (risk or concentration) and a possible remedial confidence
level, SADA estimates the location(s) for the area of concern (AOC). The
following figures evaluate the AOC for the block and site scale frameworks.
For a fixed cleanup goal (e.g. 1E-6 risk for a residential scenario, 2.7
pCi/g), the block scale can be a highly conservative approach relative
to the site scale, especially for risk assessment (depending on remedial
unit size). When the user defines a subset of the site (or the entire
site) using the polygonal definition tool (see the polygon in Visualization),
the site scale framework only refers to the interior of this polygon.
The following figures demonstrate both decision frameworks for the same
cleanup goal of 1E-6 risk for the residential scenario.
Block Scale
Site Scale
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