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Over the past few years there has
been an increasing awareness of issues surrounding land
contamination and the potential for chemical substances
upon, in or beneath the ground to impact upon people,
animals and the wider environment. The government has
set a target of 60% new build on previously used land,
often referred to as ‘brownfield sites’.
Frequently these sites have some form of contamination
present upon them usually arising from past activities,
particularly those sites of an industrial nature.
Risk Assessment has become the essential tool
for site investigations as the Environmental Protection
Act (EPA) Part IIA requires a risk based approach to
be used when to assessing potentially or actually contaminated
sites. This risk based approach is also required as
part of the planning process for new developments.
Legislation and guidance regarding
contaminated land requires the landowner and/or the
developer of a site, which is potentially contaminated,
to undertake a site investigation which is fit for purpose.
Site history is often complex and could involve several
different industrial uses or activities that may have
lead to ground contamination from a wide variety of
different sources.
Sites that have been used for one
type of process may have become contaminated from a
potentially large number of contaminants;
processes change with time, chemicals are phased out
of use and newer ones replace them, the layout of operations
can be altered, demolition and reconstruction can also
affect the likely presence and distribution of contaminants.
The investigation of contaminated
land can be correspondingly complex and is ideally undertaken
using a phased approach as identified in BS 10175. The
need for and hence the cost of particular elements of
an investigation are managed pro–actively depending
upon the findings of the previous phase. Subsequent
phases can then be carefully targeted. This avoids unnecessary
work being undertaken. The phased approach typically
consists of the following stages.
Historical research and review of
available information from sources such as archives,
plans and records, databases and regulatory authorities
to discover the past and current activities at a site
and to assess them for potentially contaminative processes,
to determine the potential for the presence of contamination.
The Phase 1 Desk Study identifies
any potential sources of contamination resulting from
the current and / or historical activities at the site.
The report will also identify any
potentially sensitive receptors, e.g. humans, surface
watercourses, aquifers, buildings or ecological receptors
and collate the information relating to the site’s
environmental setting i.e. geology, hydrogeology, industrial
activity, location of controlled waters (canals, estuaries,
lakes, ponds, rivers, springs, aquifers), pollution
incidents and proximity to open/closed landfill sites.
This information is then used to undertake
a qualitative Risk
Assessment through the development of
a conceptual model for the site. The
conceptual model identifies any Significant
Pollutant Linkages which may be present.
If Significant Pollutant
Linkages
are present then a Phase 2 site investigation may be
required to quantify the risk and also to assess the
potential for environmental liability associated with
the site.
An intrusive site investigation is
then undertaken to investigate each aspect highlighted
by the Phase 1 desk study, historical research and walkover
survey. This comprises exploratory holes constructed
using the most appropriate method for the site to investigate
the local subsurface strata.
The Phase 2 intrusive
contaminated land investigation is designed and implemented,
using a variety of in situ exploratory methods, depending
on factors such as sensitivity of the area, ground conditions
(anticipated geology, hydrogeology, the expected presence
of old foundations or other obstructions, which may
have an impact on the technique selected), size of site
and type of contaminants identified by the desk study
as potentially present.
Chemical analysis of soil and water
samples for common contaminants is performed to establish
the concentration and extent of any contamination present.
A Risk
Assessment, using the “source-pathway-receptor”
model would then be carried out, this assessment may
be Qualitative or Quantitative dependent upon the site.
If a sensitive water receptor such
as groundwater is identified beneath (or within the
vicinity of) the site, then the investigation can also
involve assessment of groundwater, using chemical analysis
of water samples and computer modelling aided by various
packages to quantify the risks posed. (See Groundwater
Investigations).
If remediation is deemed necessary
following the Phase 2 works, then a site specific remediation
methodology can be produced. Design of a site specific
remediation methodology, as with all stages of investigation,
involves consultation with the regulatory authorities
to ensure satisfactory design and implementation of
the remediation programme.
This can include delineation of contamination
hot spots, further soil sampling, chemical analysis
and additional monitoring, if additional information
is required to supplement the previous investigation(s).
A wide range of remediation techniques
are available and the methods chosen are dependent upon
a range of factors including contaminant type and distribution,
environmental sensitivity of the site, intended end
use, cost and timescale etc. For information on our
remediation work, see Waste
Management, Groundworks and Remediation.
Voelcker Consultants has been involved in a wide range
of development projects requiring site investigations
of potentially contaminated sites. We are able to provide
a comprehensive contaminated land investigation service
including:
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Production
of Phase 1 Desk Study reports through
extensive information gathering, analysis and interpretation;
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Designing, commissioning
and supervising Phase 2 Intrusive
Site Investigations, to meet the requirements of
both the client and statutory authorities; |
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Design & Implementation
of remedial schemes and undertaking post remediation
monitoring (Phase 3); |
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Validation of remediation
(Phase 4) and production of Post
Remediation Validation Reports and remediation statements; |
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Liaison with statutory
authorities (e.g. the Environment
Agency, local authorities, HSE etc.); |
Voelcker Consultants undertake site
investigations and reporting in accordance with relevant
guidelines including BS 10175: 2001, DEFRA
and Environment
Agency guidance. We have extensive experience in
undertaking site investigations on a wide range of sites.
Please contact
for a discussion of your requirements.
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Risk Assessment