Tired and tested technology
The majority of land reclamation schemes in the UK still rely heavily on straightforward excavation or encapsulation to clean up contaminated sites. Innovative Treatment Technologies (ITTs) apply chemical, biological or physical processes to destroy, change or remove contaminants from soil or water to render them immobile. Whilst such technologies have gained much wider acceptance in other EU countries and in the US, their acceptance within the UK has been restricted. Mike Dinsdale and Tim O'Hare of Mayer Environmental Services Ltd examine some of the reasons why.
The variety of novel clean-up techniques available is almost endless, and
new techniques or improvements on existing techniques are constantly being
introduced. The US EPA Vendor Information System for Innovative Treatment
Technologies (VISITT) currently lists 325 innovative treatment technologies
provided by 204 vendors. In Europe the NATO/CCMS Pilot Study on Research,
Development and Evaluation of Remediation Technologies for Contaminated Soil
and Groundwater also provides a useful overview of developments in ITTs.
Conventional excavation techniques are ‘certain’ (at least that is the
received wisdom): a once-and-for-all solution. A developer can quantify the
cost of removing contaminated material and the time it will take. And since
contaminated material is removed from site to landfill there is no issue of
Developers are often, therefore, naturally reluctant to apply new or
unproven techniques when treatment costs and timescales cannot be accurately
defined and residual liabilities remain unquantified.
UK remediation practice enshrines the concept of ‘fitness for purpose’. Land
is only required to be remediated to the extent that it is sufficiently
clean for the intended use of the site. This philosophy has been reaffirmed
by the Government and looks set to form the basis of site remediation
practice into the millennium, with the resultant implications for the
application of ITTs.
Over the last 10 years or so there has been a rapid introduction of a raft
of substantial environmental legislation. Much has not been tested in the
courts to establish legal precedents. The practical result of this can be
confusion and contradiction. Developers may be unwilling to apply new
techniques because again the issue of residual liability is unclear. Where
an ITT is considered suitable it may be impossible to obtain a Waste
Management Licence for on-site treatment within the timescales of a
In the context of land reclamation, the principal regulators are the
Environment Agency and (Local) Planning Authority. Perhaps because of the
gaps in legislation and precedent, regulatory interpretation is often
inconsistent and rarely takes full account of the commercial pressures a
developer may be under. As UK land reclamation largely occurs via
redevelopment, it is surely sensible for regulation to take account of the
practical realities of developing a brownfield site. Timescale is a critical
cost factor and a four-month delay in receiving a response to a licence
application or an overly strict interpretation of legislation or current
guidance will not encourage the application of ITTs. A developer will revert
to tried and trusted methods where timescales can be predicted and costs
determined up front.
By definition, ITTs are not established technologies, and many developers
and funding institutions are cautious about relying upon techniques which
are ‘unproven’ and which leave or treat contaminants in situ. In many cases
such concerns are unfounded, as technologies such as bioremediation, soil
vapour extraction and soil washing are now established both in the UK and
overseas and have a proven, successful track record.
Received wisdom suggests that if you dig out contaminated soil from a site
and dump it in a landfill, then there is no question of any residual
liability either as a result of new legislation, legal precedent or a
different interpretation of existing legislation.
Whilst this may be largely true, it does reflect the emphasis the industry
has traditionally placed on soil contamination and the ‘fitness for purpose’ philosophy. UK guidance on the redevelopment of
contaminated land has historically been limited. This
situation has changed in the recent past with the publication
of an array of DOE (now DETR) sponsored research reports
including Contaminated Land Research (CLR) and specific industry profiles.
However, increasing emphasis on wider environmental issues has clouded the
issue. Digging out contaminated soil may well render a site
fit for the intended end use, but
it may not address other issues which could affect future liability. For
example, contaminated groundwater may be left in situ which, without
treatment, could migrate and pollute a local aquifer. Such wider
considerations, particularly in connection with groundwater pollution, may
provide some much needed impetus for adoption of new clean-up techniques.
It is still relatively cheap to landfill in the UK, and comparative costs
represent a significant barrier to the introduction of new clean-up
techniques. The introduction of landfill tax affords a fiscal control and
could provide an incentive to discourage landfilling contaminated soil.
However, the current regime exempts much of the soil likely to arise on a
contaminated site from the tax a measure designed to encourage re-use of
contaminated land and release pressure on greenfield developments.
It seems unlikely, therefore, that current Government policy on taxation
will swing the economic balance away from landfill towards treatment of
An area where Landfill Tax has bitten is in the treatment of soil wastes
which would not be exempted or which would be classed as inert and attract
the lower rate of tax (currently £2/tonne). In these cases developers
actively seek to retain material on site and therefore some forms of
treatment to create a growing medium from inert substrate can provide an
attractive and cost effective reclamation solution. Examples of this would
include blending green waste, bio-gran or other organic waste products with
inert soil or colliery spoil to produce an in situ growing medium. Whilst
purists might argue that these techniques are not strictly Innovative
Treatment Technologies, they nevertheless play an important role in land
reclamation and as a category probably represent the largest volume of
treated soil which is re-used rather than landfilled.
Most would agree that the current practice of hauling contaminated soil from
a reclamation site is not a sustainable option. Hence, despite the barriers
to introduction of Innovative Treatment Technologies it seems inevitable
that their application in land reclamation will increase. Development of the
technologies themselves has shown that, particularly for larger reclamation
projects, cost comparisons with landfilling can be favourable.
Implementation of the proposed Landfill Directive may well alter the
economic balance between treatment and landfilling by restricting the
landfilling of certain wastes or imposing requirements on pre-treatment.
The new framework for contaminated land should remove some of the
uncertainties from the current regime and will hopefully result in more
consistent and pragmatic regulation. Risk assessment will allow informed
judgements to be made about actual (rather than perceived or theoretical)
threats from contamination. This should help to mitigate the ‘let’s dig it
all out just to be sure’ philosophy and encourage novel and innovative
techniques to be applied.
Where ITTs do score is in larger reclamation projects such as the Greenwich
Millennium site where the up-front costs of mobilisation and capital can be
offset against a large treatment volume. Many ITTs are also ideal for
gradual remediation of contamination where excavation is not practical and
site disruption is required to be minimal.
Whilst the future for ITTs within the UK market may not yet be rosy, one can
at least detect a distinct pinkish tinge.
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