Introduction to Contaminated Site Management - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 46

1.6.6 Remediation Objectives

An end goal of a Risk Management procedure must be defined, and gener-
ally expressed as soil or groundwater concentration. Although the term Risk
Management objective would have been a more appropriate term, this intended
soil or groundwater concentration generally is called remediation objective (aka:
remediation goal ).
In the early days of contaminated site management, in the late 1970s, the reme-
diation objectives were commonly set at the zero level, often not supported by any
explicit considerations. Today, the goal of Risk Management generally relates to an
acceptable risk level for the relevant protection targets. The selection of protection
targets and the definition of an acceptable risk level are beyond the scope of science
and are the responsibility of decision-makers. Contrary to the appraisal of existing
soil contamination, which relates to imposed risks, Risk Management is supposed
to 'create' a desirable situation, versus certain efforts and costs. Therefore, there are
good reasons to select more protection targets and more stringent protection levels
for the objectives of Risk Management than for curative decisions on existing soil
quality.
Examples of acceptable risk levels are the Negligible Risk (NR) for human health
as a target for the soil upper layer, or the Negligible Risk (NR) for the aquatic
ecosystem as a target for the groundwater. Another option for a remediation tar-
get that is not based on risks is the (natural) background concentration (as a target
for the upper soil or the groundwater), or commercial production criteria as a target
for agricultural products.
The process of deriving remediation objectives includes the following steps:

• Selection of protection targets.

• Definition of 'policy requirements' for each protection target (e.g., 'it must be

possible to grow the complete vegetable package of a family in a vegetable
garden'; or 'the soil ecosystem must be fully protected in a nature reserve').

• Translating the 'policy requirements' into Risk Assessment terms (e.g., in

analogy with the examples above, 'exposure through the complete vegetable con-
sumption from the own garden equals the Reference Dose for exposure'; or: '95%
of the soil ecosystem must be protected (in that case, an affected fraction of 5%
is assumed as “full protection”)'.

•

Derivation of risk limits in soil or groundwater for every protection target, and
for all selected contaminants.

• Selection of the appropriate risk limit in soil or groundwater as a remediation

objective (usually the lowest of all risk limits in soil or groundwater) for all
selected contaminants.

Except for soil concentrations, alternative types of remediation objectives could
be defined. Von Lindern et al. ( 2003a ), for example, used the lead concentration
in house dust as a goal for the remediation of the Bunker Hill Superfund site in
northern Idaho, USA, since exposure through dust ingestion has been recognized