Environmental Engineering Reference
In-Depth Information
Desk study and conceptual site model
The desk study and creation of a conceptual site model (CSM) should be the
starting point for any assessment of risks to ecological receptors from land
contamination (Environment Agency
2008a
). The purpose is to establish
whether there is a reasonable possibility of linkages existing between a poten-
tial source of contamination and ecological receptors (
Fig. 9.2
). It must occur
early on in the ERA because it provides the background information needed to
develop a CSM.
A CSM is:
A representation of the characteristics of the site in diagrammatic or written form that shows the
possible relationships between contaminants, pathways and receptors
(Environment Agency
2004a
).
A desk study and development of a CSM typically follows 10 steps (Environ-
ment Agency
2008b
):
1. Establish the Regulatory Context. For contaminated land, the regulatory
context is Part 2A of the Environmental Protection Act (1990), and so the
risk assessor would refer to the statutory guidance and the list of appli-
cable ecological receptor 'protected locations' (Table A; DEFRA
2006
).
2. Collate and Assess Documentary Information. A risk assessor will need to
gather as much background information about a site as possible, including
identifying possible protected locations in the proximity of the potential
contaminants. Depending on the CPR linkage, protected areas up to 5 km
from the potential contaminants may be considered, although in most
cases 1 2 km is likely to be the limit of any assessment. Information and
location of protected areas is available from a number of sources, including
the individual UK conservation agencies (Natural England, Countryside
Council for Wales and Scottish Natural Heritage) as well as the Joint Nature
Conservancy Council. Additional information is provided by the Environ-
ment Agency (
2008b
). Having identified the presence of one or more pro-
tected areas, information about the site will be collected including maps,
existing environmental reports and records, physical information and any
other generic information about the site.
3.
Summarise Documentary Information. Once all the relevant information
about the site has been collected, a summary report is prepared to put the
information in context. The report will usually summarise the history of
the site (size, land use, previous activities etc.), the chemicals present on the
site (types, potential concentrations, distribution etc.) and the ecology of
the site (types of habitat, key communities, conservation status etc.).
4.
Identify Contaminants of Potential Concern. Once all of the information
is collated, contaminants of potential concern (CoPC) can be identified
