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

residual liability.

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

development contract.

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.

Unfounded concerns

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

contaminated soils.

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.

New framework

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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