Environmental Engineering Reference
In-Depth Information
amendments of 2% activated carbon to contaminated sediments. A similar test and
observation was done with PAH contaminated urban soils and sediments (Brandli
et al.
2008
). These technologies are currently being tested for various field situations
and can be expected to become applied at large scale in the near future.
In the Netherlands, an expert team evaluated possible risks of immobile con-
taminants including metals in sediments and submerged soils. This expert team
concluded that for each case an insight into the processes involved needs to be
established before adequate Risk Assessments and emission reduction measures
(such as reactive amendments and capping) can be applied (Schipper et al. 2009).
In general, capping should be used in environments where the long-term physical
integrity of the cap can be maintained, and environments with low turbulence are
generally desired for In Situ capping projects. The potential severity of the environ-
mental impacts associated with cap erosion and potential dispersion of the sediment
contaminants in an extreme event should determine the level of protection against
erosion (
http://www.epa.gov/glnpo/sediment/iscmain
/).
21.3 Integration of In Situ Technologies in Risk Management
21.3.1 Risk Management Concepts and Frameworks
A distinction can be made between Risk Assessment and Risk Management (Brils
et al.
2008
;see
Chapter 1
by Swartjes, this topic; Van Leeuwen and Vermeire
2007
).
Risk Assessment is a science based method using site data and models identifying
and calculating hazard, exposure, and effects at the receptor. By applying uncer-
tainty and probability models the risk, i.e., the probability for damage to a receptor
in time and space, is determined. Risk Management concerns possible responses to
risks by actions. These can be interventions such as remediation and interception
measures at the source, path or receptor, or can be in the form of alterations in the
functional use of a contaminated area. In addition, Risk Management decisions are
often based on considerations that are influenced by other factors (e.g., economic,
political, public perception). Van Leeuwen and Vermeire (
2007
) defines therefore a
third component, namely
Risk Communication
, taking the societal context, involve-
ment of stakeholders, and the current policy on Risk Assessment and evaluation into
account.
Vegter et al. (
2003
) and others introduced the concept of
Risk Based Land
Management
(RBLM), integrating two key decisions for the remediation of con-
taminated land:
1.
the time frame: this requires an assessment of risks, priorities, and the longer-
term effects of measures;
2.
the sustainability of the intervention measure or change in functional use: this
requires an assessment of overall benefits, costs and environmental side effects,
the value and condition of the land, public and local community perceptions and
other issues.
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