XYZ Enterprises is a fictitious case study used to
illustrate some of the steps in the Risk Assessment framework
that may be undertaken in an RA for a contaminated site.
The specific details of this example are fictional.
They are not attributable to any single site, but its characteristics,
contaminants, pathways and receptors provide an indication of the
factors that often drive RA's at NZ sites.
Although the RA assessor in the example is a
corporate site owner with multiple sites of concern, the process applies
equally to any site owner, manager or assessor with single, or multiple
This example should not be taken as an exhaustive
examination of all possible contaminants, pathways and/or receptors. The
RA assessor should satisfy him/herself as to the specific factors
present at the site of interest.
The following indicates the general sequence of events
our assessor at XYZ Enterprises used. The steps below reflect both
the RA framework and its stages as well as the increasing
of detail and quality of the data required at each of the tie
At each tier, the five key
tasks in the inner part of the framework, Problem
Identification, Receptor Characterisation,
Exposure Assessment, Toxicity Assessment, and
Risk Characterisation, are undertaken to
provide information and data in order to make a risk management decision or to decide
whether it is necessary to proceed to the next level of detail.
Broadly, the degree
of detail and quality of the data at each level can be described as:
- Tier 1: Qualitative
- Tier 2: Semi-quantitative
- Tier 3: Quantitative
This describes the preliminary steps
that were necessary before the decision was made to conduct an RA and
consisted of four main tasks - identification of
potential sites, preliminary
site characterisation, site classification, and
In this step a qualitative screening process is needed
to determine whether there is a potentially complete pathway between the
contaminant of concern and potential receptors, and whether contaminant concentrations exceed benchmark or guideline
values for the relevant receptors or media of concern.
Level 2 ERA is primarily intended to
involve a more intensive literature search to modify the assumptions of
the benchmark criteria used in Level 1 and to undertake a preliminary
customisation of ecological criteria for each contaminant specific to the
pathways, receptors, media, and environmental conditions found at the
site and to establish modified assessment criteria. Usually a Level 2 ERA is expected to be the most detailed level of ERA
undertaken for most sites.