Transitions - Sustainable Design: The Science of Sustainability and Green Engineering - page 83

down the contaminants over an acceptable amount of time. Both will probably
strongly recommend ongoing monitoring to ensure that the contaminants are in
fact breaking down and to determine that they are not migrating away from the
site. Does this mean that one is less competent or environmentally aware than the
other? Certainly not.
Various design recommendations result from judgments about the system at
hand, notably the initial and boundary conditions, control volume, and the
constraints and drivers that we discussed in Chapter 2. In each expert's judgment,
the solution designed calls for different approaches. For example, a site on Duke
University's property was used to bury low-level radioactive waste and spent
chemicals. The migration of one of these chemicals, the highly toxic paradioxane,
was modeled. A comparison of the effectiveness of active versus passive design
is shown in Figure 3.1. Is this difference sufficiently significant to justify active
removal and remediation instead of allowing nature to take its course?
Both approaches have risks. Active cleanup potentially exposes workers and
the public during removal. There may even be avenues of contamination made
possible by the action that would not exist if no action were taken. Conversely,
in many cases, without removal of the contaminant, it could migrate to aquifers
and surface water that are the sources of drinking water, or could remain a
hazard for decades if the contaminant is persistent and not amenable to microbial
degradation. Thus, green engineering requires consideration of risk management,
and managing these risks requires thoughtful consideration of all options.
Risk management is an example of optimization. However, optimizing among
variables is not usually straightforward for green engineering applications. Opti-
mization models often apply algorithms to arrive at a net benefit/cost ratio, with
the option selected being the one with the largest value (i.e., greatest quantity
of benefits compared to costs). To economists and ethicists this is a utilitarian
approach. There are numerous challenges when using such models in environ-
mental decision making. Steven Kelman of Harvard University was one of the
first to articulate the weaknesses and dangers of taking a purely utilitarian ap-
proach in managing environmental, safety, and health risks. 1 Kelman asserts that
in such risk management decisions, a larger benefit/cost ratio does not always
point to the correct decision. He also opposes the use of dollars (i.e., monetization
of nonmarketed benefits or costs) to place a value on environmental resources,
health, and quality of life. He uses a logical technique of reductio ad absurdum (from
the Greek, η ' εις τ o α δυν α τ o ν α π αγ ω γ η , “reduction to the impossible”),
where an assumption is made for the sake of argument, a result found, but it is
so absurd that the original assumption must have been wrong. 2 For example, the
consequences of an act, whether positive or negative, can extend far beyond the
act itself. Kelman gives the example of telling a lie. Using the pure benefit/cost
ratio, if the person telling the lie has much greater satisfaction (however that is
quantified) than the dissatisfaction of the lie's victim, the benefits would outweigh