Introduction to Contaminated Site Management - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 47

as a principal exposure pathway. Von Lindern et al. ( 2003b ) focused on lead blood
levels as a remediation objective of the Bunker Hill Superfund site.
In some cases there are good reasons for focusing on lower soil concentration
levels as remediation objectives than is strictly needed for human health protec-
tion. Several remediation technologies, such as Dig-and-Dump for example, do not
always allow for 'gradual' risk levels after remediation, but may result in a clean
soil.
1.7 A Closer Look into Risk Assessment
1.7.1 Types of Risk Assessment
1.7.1.1 Purpose
Generally speaking, contaminated site Risk Assessment offers two possibilities.
First, Risk Assessment can be used to investigate a specific site. This type of Risk
Assessment is called site-specific Risk Assessment or actual Risk Assessment .In
this case, information about the specific site is available. Second, Risk Assessment
can be used to derive Soil Quality Standards. This type of Risk Assessment is
often called potential Risk Assessment or generic Risk Assessment . Often, generic
Risk Assessment is the first step in Risk Assessment frameworks, followed by site-
specific Risk Assessment when the generic Risk Assessment does not result in a
clear decision as to risks.
1.7.1.2 Site-Specific Risk Assessment
Risk Assessment related to a specific site is often called actual Risk Assessment .
From this perspective, 'actual' is used in the sense of 'existing in fact' and not nec-
essarily in the sense of 'existing at this moment'. It is possible, for example, that a
Risk Assessment might be performed for the purpose of investigating whether it is
'safe' to reside at a specific residential site, which might be contaminated. In that
case, the relevant time frame for Risk Assessment can vary from several years up to
several decades, depending on the time frame over which the specific contaminants
reveal effects. Therefore, it does not make sense, for example, to focus on the actual
layout of the garden, with or without vegetables grown for one's own consumption,
since this layout may change over a period of years or decades. In fact, an assump-
tion needs to be made for a representative contribution of vegetables from one's
own garden, independent of the situation at the time that the Risk Assessment is
performed. Specifically, in situations in which a Risk Assessment is performed for
the purpose of investigating the risks for a future land use, it does not make sense
to base the Risk Assessment on features that relate to the present land use. For this
reason, the term 'site-specific Risk Assessment' is used in this topic, rather than
'actual Risk Assessment'.