Assessing Environmental Impact 15objective is difficult to apply in practice. Alternatives may be articulated by various
interest groups in and out of government, or the engineer may be left to create his or
her own alternatives. In either case, there are normally one or two plans that, from
the outset, seem eminently more feasible and reasonable, and these are sometimes
legitimized by juggling, for example, selected time scales or standards of enforcement
patterns just slightly and calling them alternatives, as they are in a limited sense. As
a result, “nondecisions” are made (Bachrach and Baratz 1962), Le., wholly different
ways of perceiving the problems and conceiving the solutions have been overlooked,
and the primary objective of the EIS has been circumvented. Over the past few years,
court decisions and guidelines by various agencies have, in fact, helped to mold this
procedure for the development of environmental impact statements.
As the environmental assessment procedure has evolved, assessment of socioeco-
nomic impact of the project has played an increasing role. In addition to direct economic
impact (number of jobs, total household income, property values, etc.), socioeconomic
impact includes impacts on archaeological and historical sites, impacts on sites that
have cultural significance and on cultural practices, and environmental justice impacts
(assessments of excessive impacts on minority populations). As impact assessment
moves into successively “softer” science, overlap with questions of ethics and val-
ues increases, and the engineer must take care to differentiate between quantitatively
measurable impacts and qualitative assessments that might be influenced by value
judgments. Risk assessment has also become increasingly important in environmental
assessment.
This text focuses on the “hard science” and risk assessment aspects of environmen-
tal assessment. The socioeconomic aspects of environmental assessment are usually
analyzed by experts in the social sciences and economics, and so are not discussed
in detail. Assessment of future impacts frequently requires probabilistic risk analyses
instead of deterministic analyses. Risk analysis is discussed later in this chapter and in
Chap. 3.
An environmental assessment must be thorough, interdisciplinary, and as quanti-
tative as possible. The writing of an environmental assessment involves four distinct
phases: scoping, inventory, assessment, and evaluation. The first phase defines the
scope or extent of the assessment. For example, if the project involves transporting
construction materials to a site, the scope may or may not include the environmen-
tal impacts of that transportation. At least one public hearing is generally held on
scoping.
The second phase is a cataloging of environmentally susceptible areas and activ-
ities, including socioeconomically impacted areas. The third phase is the process of
estimating the impact of the alternatives, including cumulative impacts, and the impacts
of a “no action” alternative. The last phase is the interpretation of these findings, which
is often done concurrently with estimating impacts.
All federal agencies are currently required to assess the environmental impacts of
extended projects and programs as well as individual projects under their jurisdiction.
The impact assessment for an extended or multifaceted project is frequently called a
generic environmental impact statement or GEIS, while an assessment for an entire
program is referred to as a programmatic environmental impact statement, or PEIS.