Environmental Engineering Reference
In-Depth Information
23.7.1 Risk Reduction
The initiation of decisions relating to risk reduction comes from the results of Risk
Assessment, which in turn can inform the choice and objectives for solutions. It is
important to note that the importance of human health risks, ecological risks or more
general environmental risk like the risk of spreading of contamination in groundwa-
ter, surface water or air may receive equal weight in the Risk Assessment of the site
but in the design of the solution things may look different, dependent on the require-
ments for future use. Human health and ecological requirements for parking lots are
of course much less stringent than for houses with gardens where human expo-
sure is more likely and ecological functions are needed for the gardens. The risk
of spreading of contamination may dominate the discussion about risk reduction in
the parking lot situation. The final choice about risk reduction needs to consider
the key decisions within RBLM referring to the time frame and the choice of the
solution.
23.7.1.1 The Time Frame
One key issue in relation to the timeframe is determining when to intervene, control,
or reduce risk. This requires prioritisation and Risk Assessment procedures based
on an assessment of the fitness for use of the site and of the need for protection of the
environment. Many Member States of the EU and industries have already developed,
or are in the process of developing, this type of approach in their decision-making
frameworks for contaminated sites.
The CARACAS network considered a number of aspects of Risk Assessment
relevant to determining when action is necessary and to priority setting in relation
to human health and environmental risk like risk for ecosystems, spreading of con-
taminants in groundwater or risks for specific ecological functions. Clearly, in terms
of total resource use, it is equally important to decide when it is safe to postpone
action on sites to avoid unnecessary expenditure.
However, the need to conserve or enhance a resource - for example soil or water -
may also set the timeframe for action. Action may be justified rather sooner than
later, because the long-term care requirements are too great a burden. There are
other drivers for action, for example the need to reuse the site or to increase the
value of the land for the owner or developer. The urgency of a site remediation is
therefore a function of one or more of these environmental, economic and social
factors, and for most large projects a combination of all of them.
23.7.1.2 Choice of Solution
The factors that affect the urgency or priorities for action also determine a key inter-
face between timeframe and choice of solution, which is when the solution needs to
become effective and for how long. Another factor in the choice of solution is the
way in which the solution relates to the underlying risk. The process underlying the
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