Overview and Initiating the Environmental Impact Analysis and Assessment - Environmental Impact Analysis: Process and Methods - page 157

is nearing implementation without full environmental evaluation or stake-
holder input. The “credit card” diagram (Figure 4.1) is a simple visualiza-
tion of the goal of alternative description. The features of the alternative that
can interact or overlap with environmental resources should be described in
detail, while the characteristics with little potential to affect environmental
resources require little or no description.
The process must be relatively equal and balanced among all alternatives
evaluated in detail. For example, providing close to a full engineering design
for one alternative and a general qualitative description of others can indicate
an alternative preference or even de facto selection, thus compromising the
goals of environmental analysis. Similarly, the level of detail does not have
to be the same for all aspects of the alternatives. As discussed above, where
there is overlap with environmental resources, the description should be
more detailed. It is also important for the description to be a balance of tech-
nical detail and explanation understandable and useful to all stakeholders.

4.5.3 Screening of Alternatives

Alternative screening can take several forms and levels. The first step
in any alternative screening process as part of an environmental impact
analysis is to determine if an alternative under preliminary consider-
ation meets the purpose and need. If the purpose and need cannot be
accomplished, then the alternative either must be modified so that it does
accomplish the intended purpose or eliminated from detailed consider-
ation in the environmental impact analysis. Screening against the purpose
and need can efficiently be accomplished by establishing a list of criteria
with specified thresholds needed to meet the purpose and need. This list
guides the initial description of alternatives because there must be suf-
ficient definition and detail of the alternative developed to compare with
the purpose and need screening criteria. The screening of alternatives for
the Washington Aqueduct Water Treatment Residuals Management EIS
(see Section 10.4) and the USCG DCR EIS (see Section 10.2) are examples
of establishing criteria and thresholds to compare alternatives with the
purpose and need and eliminate those which do not measure up. As with
these examples, if an alternative is eliminated from detailed evaluation, it
is critical that the reasons for elimination are well documented and avail-
able to stakeholders.
After the alternatives that meet the purpose and need have been identified,
the list can sometimes be further screened by a “fatal flaw” analysis. This form
of screening maximizes environmental analysis efficiency and focus by estab-
lishing criteria that would singly eliminate an alternative from further consid-
eration. Thus if an alternative did not satisfy any one of the specified criteria,
it would be considered “fatally flawed” and not carried forward. Evaluation
of the alternative with respect to detailed description, costs, and impacts in
other environmental resources would not be necessary, thus focusing the