Site Investigation

A contaminated land site investigation is a phased approach to determining whether a
significant risk exists from the type and extent of any contamination in, on or under a
site. It involves characterising your site on a conceptual model which is updated as you
carry out research (phase I), sampling and analysis (Phase II). Where contamination is
identified a risk assessment requires to be carried out to determine whether the
contamination is likely to have an impact on human health, controlled waters or the
environment.

Conceptual Model

A Conceptual Model is a representation of its site and surrounding area. It is a simplified
description of the environmental conditions and it’s purpose to identify potential sources
of contamination, receptors which may be affected by contamination (for example, human
health, water courses, the environment) and pathways which may link the two (for example
the food chain, drinking water supply, inhalation of dust). A Conceptual Model is usually a
mixture of pictures, diagrams and text and it is used to provide a vision of the site. It
is important that your conceptual model is updated regularly during your site
investigation.

Phase I (Desk Study)

A Phase I investigation is the research which should always be carried out before any
sampling or analysis is undertaken. It’s purpose is to identify whether the site has been
subject to contaminative uses as well as considering potential receptors and pathways.
Examples of the information which should be looked at when carrying out a Phase I
investigation includes the following:

Site history – previous and current uses of the site and neighbouring land.
Geology, hydrology and hydrodgeology.
Local Authority and SEPA Records including current and historic licences and consents.
Site Walkover.

Once gathered this information can be used to aid the design of the Phase II investigation.

Phase II (Intrusive Investigation)

There are three types of Phase II Investigation, Exploratory, Main and Supplementary. An
Exploratory Investigation may be used to obtain and indication that your Conceptual Model
is generally correct before carrying out a Main Investigation. This is likely to involve
limited sampling and analysis of one or more of the following: soil, surface water, ground
water and soil gas. An Exploratory Investigation can be used to confirm information
suggested by the Conceptual Model for example, location of underground tanks. Non intrusive
techniques for example, for locating below ground structures may also be employed during
the Exploratory Investigation to provide further information towards the Main
Investigation.

The Main Investigation will involve more extensive collection and analysis of soil, water
and gas samples. It’s purpose is to obtain all the necessary information for the assessment
of human and environmental risks. It should enable a full assessment of risks to be carried
out along with the design of remediation works and quantification of costs.

A review of the outcome of the Main Investigation may identify aspects where there is a
deficiency in information. In this case a Supplementary Investigation may be carried out
for example, to improve the accuracy of costs of remediation work. A Supplementary
Investigation will be designed to produce quite specific information.

Remediation

Remediation is the action taken to decontaminate a site or reduce the contamination to an
acceptable level. Examples of types of remediation are as follows:


Removal of contaminated soil to an appropriate landfill site with any void created
replaced, if necessary, with uncontaminated soil.
Containment of contamination, for example, lining and capping of the site.
Treatment by chemical, physical or biological processes to destroy, remove or make safe
contaminants.

Verification/Monitoring

Following remediation verification works may be required to confirm that the remedial
actions have been successful. Ongoing monitoring of sites containing contamination or those
which have been remediated may also be necessary.