In Situ Remediation Technologies - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 968

structure to use for soil and sediment remediation, since this framework is just like
the technological measures (Section 21.2 ) oriented at sources, pathways and recep-
tors. Moreover, it also offers possibilities to further develop the sustainability part of
soil and sediment management. The biophysical soil-sediment-water system can be
defined as one of the receptors providing goods and services to society. In this way
the framework connects to the concept of Ecosystem Services which is currently
considered as a new leading principle in sustainable environmental management
(see Chapter 13 by Swartjes et al., this topic), addressing not only soil and sediment
remediation but also river basin management, climate adaptation and mitigation,
and the sustainable use of the subsurface.

21.3.2 Risk Management Application

To make risk information easily accessible for decision making, one often chooses
a generic tiered approach using traffic light models (IRGC 2007 ), distinguishing a

• green mark for acceptable risks: no further actions are needed;

• yellow mark for acceptable: actions are needed to reduce risks over time and

space, in accordance to the ALARP - “as low as reasonably possible” - principle
and the BAT “best available technique” - approaches;

• red mark for acceptable risks: direct interventions have to be made by remediation

actions and/or by changing the functional use of the site.

This concept has been applied for Natural Attenuation in groundwater (Sinke
et al. 1998 ), human health risks associated with contaminated soil and groundwater
(Bien et al. 2005 ), and emission risks from sediments contaminated with metals,
PAH and hydrophobic chlorinated contaminants (such as hexachlorocyclohexanes,
polycholorobenzenes, Dieldrin, and PCB's) (Malina et al. 2002 ).
Risk Assessment requires a minimum of data and information related to the site
before it can be used in a preliminary set up for Risk Management. In practice,
and especially in large areas with soil and sediment contamination, this is often
complicated. Acquiring site information and building up of an understanding of all
contaminant migration pathways, receptor exposure routes and uncertainties often
requires time and investments, while management decisions need to be taken in
much shorter time frames. A solution for these situations is to form a group of
experts and stakeholders that estimates the risks and evaluates various interven-
tion and remediation options (Malina et al. 2002 ; Ter Meer et al. 2008 ). Here,
natural science based risk data, expert judgements and socio-economic arguments
of stakeholders modulate the outcome of Risk Management decision. For large
scale problems such as sediments in rivers and lakes, and contaminated land and
groundwater at Megasites, a cyclic evolving approach is needed. In this way Risk
Assessments and Management strategies can evolve with the build up of informa-
tion and understanding of processes occurring at the site or region. This generally
requires a time frame of years to a decade (Ter Meer et al. 2008 ).