Sustainability and Remediation - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 897

can be applied to destroy contaminants in situ (e.g. bioventing, phytoremediation)
or ex situ (e.g. biopiles). Chemical methods destroy (e.g. in situ chemical oxi-
dation), transform or stabilise contaminants. Physical methods exploit differences
in soil or contaminant properties such as particle size distributions (soil differ-
ences) or density or volatility (contaminant differences) to separate contaminated
and uncontaminated fractions and, hence, reducing the volume of material that needs
further treatment or disposal. Thermal methods can enhance other technologies (e.g.
six phase soil heating can improve the efficiency of soil vapour extraction) or destroy
(e.g. incineration), relocate (thermal desorption), or isolate (vitrification) contam-
inants. Solidification/stabilisation treatments are generally chemical and physical
measures which reduce the physical accessibility and/or chemical availability of
contaminants. See for more details on in situ remediation technologies Grotenhuis
and Rijnaarts ( Chapter 21 of this topic). For more details on Natural Attenuation see
Chapter 22 by Peter et al., this topic.
An important tool in planning and verifying Risk Management is the site concep-
tual model . The conceptual model comprises a plan, cross section and topological
(network or matrix diagram) graphic with associated, often tabulated, text about
the sources, pathways, receptors and associated uncertainties or assumptions. The
network diagram provides a simple template on to which components of the Risk
Management strategy can be placed to permit a simple check that all the contaminant
linkages have been broken. The use of the network diagram in this way can facilitate
the design of cost effective, socially acceptable and environmentally benign inte-
grated solutions and also facilitates communication about potential risks between
the different stakeholders involved in a particular project.
Typically most remediation work has been initiated for one or more of the
following reasons:

• to protect human health, or the environment (including groundwater);

• to enable redevelopment, including restoration of sites for amenity, or bioenergy

purposes;

• to limit potential liabilities, for example to improve corporate balance sheets or

to facilitate sale or transfer;

• to repair or enhance previous remediation work that has been found to be

inadequate.

In all cases the underlying stimulus or intention is to mitigate risks to human
health, the environment, groundwater and surface waters and buildings, as generally
set out in the prevailing legislative and regulatory framework. Mitigation of these
risks is therefore a prerequisite, without which the remediation is essentially func-
tionless, and hence de facto unsustainable. Risk Management must be achieved and
evidence must be captured and reported that demonstrates that it has been broken
to all stakeholders (regulators, future purchaser or tenant, other stakeholders). For
example, the UK policy view is that: a fundamental principle of sustainable devel-
opment is that the condition of land, its use and its development should be protected
from potential hazards. Without appropriate action, the presence of contaminants