It is assumed that you have already identified a particular site as requiring
The objective of Problem Identification is to take stock of the problem for a
particular site, and answer the question:
'What do we think the problem is?'
"What information should be collected
and assessed to confirm our understanding of the problem?"
The main outcome of the Problem Identification stage is to set the overall
purpose and objectives of the RA and to determine the likely data requirements.
This step should:
- Clearly identify what aspect of the RA needs to be addressed;
- Set the objectives of the RA (what will and will not be considered), and
- Identify what information needs to be collected, analysed and assessed.
Risk Assessment Objectives
The specific objectives of the assessment will depend on the state of
knowledge about the site.
- If no previous studies or sampling have been undertaken, the objectives
may relate to establishing whether contamination is present, at what
concentrations and in what media.
- If there has been a previous investigation, this step may identify that a
particular contaminant pathway needs to be further assessed.
- If previous Tiers of a RA have been completed, this step may address a
particular information gap.
The objectives of a Risk Assessment will vary depending on the nature of the
site and the Tier at which the Risk Assessment is being undertaken.
Tier 1 - Problem Identification
The first part of this step is to assess existing information and identify
the problem that the RA is trying to address.
Any preliminary findings about the site should be documented. Care should be
taken to make sure that all available information is carefully assessed before
the next stages of the RA are undertaken. At this stage it is important to
identify and document the following details:
- current and historic land uses
- potential/actual contaminants of concern
- potential pathways
- potential receptors
- areas of uncertainty.
Problem Identification should consider a wide range of possible contaminants,
receptors, and pathways. This should lead to the formulation of a conceptual
site model that can be tested through the RA process, and provide the basis for
developing the objectives for undertaking a Tier 1 assessment.
In most cases some general information about the site should be available
from the Initiation stage. This should include
current and past land uses, consent information, and site records. Further
information is generally necessary to undertake a full site
- land use and land-use history:
- identify existing and past land uses on site
- identify nearby existing and past land uses
- document any gaps in these records
- identify what chemicals or materials were used at the site (types,
quantities, processes, storage, and disposal).
- identify and document any incidents of chemical releases and possible
- identify potential or possible contaminants of concern
- identify other contaminant sources (e.g. nearby factory, natural
contaminant source), and
- broadly define the surrounding environment and identify:
- potential ecological values
- buildings or heritage sites
- sensitive land uses (e.g. school) or human receptors, and
- cultural sites.
Using this information, you should draw preliminary conclusions on the
following key factors:
- contaminants of concern;
- potential receptors; and
- main pathways (contaminants release, transport and fate mechanisms).
Any assumptions used in completing the site characterisation, and any
information gaps should be clearly documented.
An example checklist is
provided to help you to undertake a site characterisation and a completed
example is also provided for the XYZ Enterprises
It is often useful to develop a conceptual model in the form of a flow
diagram or site map to identify and clarify the problem and to identify any
information gaps. Examples of a conceptual
model diagram for XYZ Enterprises is shown, but you may choose to undertake
this process using a different diagrammatic approach. Examples of other
conceptual models are shown in USEPA 1998 Appendix C.
The construction of a simple site model is a useful tool to help characterise
a site. A large number of site visualisation and
characterisation models or software packages have been developed in recent
years. These models may assist you in fully identifying the problem at the site