June 2010 - NHBC Home

Issue 47
June 2010
Contaminated Land - New Soil Guideline Values
Soil Guideline Values (SGV’s) were
originally introduced by DEFRA
in March 2002 for a range of
contaminants that may be found in
the ground on brownfield land or
previously developed sites. The SGV’s
were specifically developed for use
in assessing the risk to human health
from contamination in soils as part
of the Contaminated Land Exposure
Assessment (CLEA) framework for
use in the UK.
The CLEA framework and SGV’s were
developed to provide authoritative
guidance in support of the
implementation of Part 2A of the
Environmental Protection Act 1990
that laid down the new regulatory
role for Local Authorities dealing
with land contaminated and also to
provide a more robust and scientific
method of assessment to replace
the previous guidance: 1987 ICRCL
(Interdepartmental Committee on
the Redevelopment of Contaminated
Land) recommendations for action and
trigger levels for contaminants in soils.
However, since the original publication
in 2002 further detailed scientific
reviews together with extensive
consultations with stakeholders in
the contaminated land industry have
resulted in a number of fundamental
revisions to the contaminated land
framework and the model known as
CLEA UK used to produce SGV’s.
As a result, in July 2008, the 2002
SGV’s were withdrawn as they no
longer reflected the updated UK
approach to human health risk
assessments.
From late spring 2009, new SGV’s
have been produced and published
for a variety of contaminants using an
updated framework and model now
known as CLEA 1.06. These revised
SGV’s are recognised in the UK as
being authoritative and scientific. They
should be used as a tool to aid the
evaluation of whether a concentration
of a contaminant in near surface soils is
‘acceptable’ in the assessment of long
term risks to human health for various
land uses including residential.
SGV’s are intended only to assess
long term risks to human health from
contaminants in soils and they do not
take into account other issues such as:
• Risks for short term exposure
• Other types of risk to humans, such
as fire, suffocation and explosion
• Non-human receptors, for instance
ecological, controlled waters,
property, domestic produce or
domestic pets
• Contaminant sources arising from
and to controlled waters (ground
water)
• Free phase products in soils or
groundwater beneath the site (e.g.
hydrocarbons such as oils, diesel,
petrol).
DEFRA has an ongoing programme
for publishing SGV’s for potential
contaminants in soils and during
2009 values have been released
for the following; Benzene, Toluene,
Ethylbenzane, Xylene (Hydrocarbon),
ACTION
Mercury, Selenium, Arsenic, Nickel,
Phenol, Cadmium and Dioxin’s including
PCB’s.
When assessing contamination
on a site, representative site soil
concentrations at or below an SGV
indicate that it is unlikely that there
is a significant possibility of harm
to human health and the site can be
considered safe for development. When
concentrations exceed an SGV, there
may be a potential risk to human health
and further risk assessment is required
to determine whether remediation is
necessary.
Due to the complex nature of contamination, it is recommended by
the NHBC that a suitably qualified person/consultant should always
be used to investigate the site, assess the risks and develop any
remediation strategy as necessary.
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