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XYZ Enterprises Example

What is a contaminated site?

Who does what?

Why is it important?

What is risk management?

Risk assessment fundamentals

Risk assessment methods

Limitations of risk assessment

What are RA tiers?


Problem Identification

Receptor Characterisation

Exposure Assessment

Toxicity Assessment

Risk Characterisation

RM Decisions

Project Initiation

ERA Tier 1

ERA Tier 2 (Advanced)

ERA Tier 3 (Advanced)






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 sites.

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  degree 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

Step 1 - Project Initiation

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

Step 2 - Tier 1 RA 

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.

Step 3 - Tier 2 RA

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.

Step 4 - Tier 3 RA


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Page last updated: 01 May 2007

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