Remediating Contaminated Land

The costs and benefits of land remediation

It is estimated that there are 100,000 sites in the UK that are contaminated, 0.2% of the country’s land. These need either to be cleaned up so they can be re-used to meet the land shortage and conservation of green areas, or simply to ameliorate the pollution.

The importance of this was emphasised when the British Olympic Association said that one key benefit of London staging the 2012 Olympic Games will be that it will “stimulate and bring forward the comprehensive upgrade of the East End environment by developing contaminated and under-used land.”

The estimated total clean-up costs for remediating the UK’s 100,000 sites range from £9-20 billion. That is on average £200,000 per site. Some sites are going to cost a lot more and some less, but any figure of this order is quite a bill to foot and is going to eat into the funds of businesses around the UK. So will they do it?

Well they do not have much choice. Part IIA of the Environmental Protection Act (1990), which was introduced by section 57 of the Environment Act 1995 and came into force in April 2000, introduces a regime for identifying and dealing with contaminated sites in the UK. The regime requires a risk-based approach consistent with good land management techniques. There are other drivers to remediating land, such as a requirement of a planning application for a proposed development of the land. However it is Part IIA that many businesses are likely to find themselves forced into completing (a Works Notice may be issued by the Environment Agency before this if there is actual or potential harm to controlled waters).

The responsibility for implementing the contaminated land regime belongs primarily with local authorities (and the various UK environment agencies for any land designated a special site).

Their responsibility includes the requirement to inspect and identify land under their jurisdiction that meets the definition of contaminated land, i.e. any land which appears to the local authority in whose area it is situated to be in such a condition, by reason of substances in, on or under the land, that: a) significant harm is being caused or there is a significant possibility of such harm being caused; or b) pollution of controlled waters is being, or is likely to be, caused.

When dealing with potentially contaminated sites, the key question that must be answered is ‘does the soil concentration of contaminant X pose a risk to human health or the environment?’ The Soil Guideline Values (SGVs) will help to answer this question – SGVs represent ‘intervention values’, which if exceeded indicate potentially unacceptable risks to site users. Exceedance of SGVs may also indicate that further investigation and/or remedial action may be required to protect human health Soil Guideline Values have been derived using the Contaminated Land Exposure Assessment (CLEA) model for three land uses:

• Residential (with and without vegetable growing)
• Allotments
• Commercial / industrial

Soil Guideline Values have superseded ICRCL values (ICRCL stands for the Interdepartmental Committee on the Redevelopment of Contaminated Land) in respect of assessing risks to human health. SGVs can be used in support of the application of the statutory regimes addressing land contamination, especially Part IIA of the Environmental Protection Act 1990 (the contaminated land regime) and development control under the Town and Country Planning Acts. CLAN 2/05 published by DEFRA (2005) provides advice on the use of Soil Guideline Values in the determination of land as contaminated land under Part IIA.

The intention is to build up a register of contaminated land, determining sites, which needs priority attention based on an assessment of the risk of harm (including potential) to humans and the environment if the land is allowed to remain in its present condition. Once a site has been identified as contaminated, the next step is to identify those responsible, i.e. the appropriate person. This can be the present owner of the land, previous owners and even neighbours. Whoever they are, they will have to pay for the remediation of the land.

The remediation process

So how does an appropriate person go about remediating their land when the local authority comes knocking; this after all might be the first they know of it. This should be relatively simple, as the enforcing authority is charged with “suggesting” what they consider to be the best strategy to be adopted, in other words a remediation scheme is agreed between the two parties. Even if the business does not voluntarily agree a scheme, the resultant Remediation Notice that is sure to follow will usefully provide the preferred approach to be complied with. Let us not forget that where it is identified that there is immediate danger of a need to prevent serious water pollution, the authorities may do the remedial work and charge the appropriate person, but that is a whole other subject.

The remediation strategy adopted will ultimately depend on the land’s current use, designated use (e.g. under planning permission), or intended use, rather than for any potential future use. Integral to that strategy is the best practicable technique for remediating the land to the agreed standard for release. For sites that are complex in terms of size, located near to sensitive sites or public, or contain a lot and variety of contaminating materials, a Best Practicable Environment Option (BPEO) approach may be required.

This in depth optioneering process will identify the preferred approach, taking into account a number of additional considerations beyond the contaminated land itself. Whether a BPEO is adopted or not, the usual suspects all need to be factored in when developing a remediation strategy. These are:

• Proposed land use
• Location of site to surrounding buildings, residential areas, schools, vulnerable habitats, controlled water, sources of drinking water, sites of scientific interests
• Size of site and access for remediation and disposal plant
• Regulatory requirements
• Public opinion
• Availability of services (e.g. electricity, water)
• Worker and public health and safety
• Waste disposal options
• The geological and hydrogeological features of the site

That is a lot to be considered. In simpler terms, the remediation technique chosen will involve breaking the pollution linkage by either the removal or treatment of the contaminant, breaking or removing the pathway or protecting or removing the receptor. Land remediation predominately focuses on the source of contamination, i.e. removal, treatment or physical isolation of contaminant. There are a number of remediation techniques commercially available, and more in the research and development phase. Most are variations on a theme and have their own individual merits, beyond being able to be clean up the land to a suitable standard, as well as limitations.

For example, previous uses of the site will almost certainly affect the choice of reclamation or remediation techniques. Factors such as the presence of heavy metals, mineral hydrocarbons, asbestos bearing materials, radioactive materials, fuel residues and gases with potential for flammability must be considered as these will affect and limit the choice of technique. The reclamation of contaminated land in the UK has until quite recently been achieved by the employment of broad spectrum engineering based techniques.

The most common technique for the reclamation of sites contaminated by heterogeneous waste has been the “cover up” by the application of a layer of clean material. This is not remediation and the passage of time has revealed the flaws in this approach as the contamination from the covered material can return to the surface under the action of natural forces such as capillarity i.e. liquid is pushed upwards through the ground and soil organisms whose movement through the soil carries the contamination with it. The simple cover up did not usually address the issue of groundwater pollution or sometimes even the potential for gas generation or combustion in the covered material.

Dilution of a polluted top cover can be effective where the existing cover lies over a clean underlying layer of clay for example. This technique still requires the prior removal of potentially flammable or gas producing materials as well as buried or partially buried structures and is not suitable for oily waste or where asbestos bearing materials might be present. Mixing of the cover materials is achieved by use of a high speed rotary mixer with or without the addition of imported clean fill depending upon the degree of existing contamination.

On-site encapsulation is increasingly popular because of the cost of removal of contaminated material from site, but the requisite techniques are quite sophisticated and very careful quality control measures are necessary because very little or no removal of material takes place. The Environment Agency will require assurance on a detailed technical level that the encapsulation will retain its integrity in respect of protection of the local groundwater.

Narrow spectrum techniques are now being employed to augment the existing broad spectrum engineering methods. Newer techniques are pollutant specific and they include soil washing with solvents if necessary to remove or to partly remove oily materials, bio remediation, thermal destruction, oil pumping and oil skimming from contaminated water tables, and stabilisation using cementitious materials. These techniques are expensive but necessary in order to meet the increasingly wide environmental concerns arising from reclamation schemes.

In reality, more than one technique is often required for successful clean up. This would certainly be the case if there is more than one contaminant present or the geological and hydrogeological conditions vary over the extent of the land. The remediation strategy should cover all techniques required.

In the context of contaminated land, the term remediation includes not only the undertaking of remedial works, but also the collection of additional information about the site, and the implementation of a monitoring scheme to ensure that the conditions at the site do not deteriorate to an unacceptable degree. In fact, comprehensive site investigation work undertaken before the actual remediation takes place is critical in ensuring that the correct strategy is adopted for remediation. This can be a complex undertaking and costly in terms of resources needed and time taken.

Then there is waste. There is a significant amount of debate with respect to wastes generated from land remediation. It is simple if the contaminated land is removed from site and disposed of to landfill, this is quite clearly waste. However, the rise in landfill taxes and reduction in sites taking hazardous wastes mean this option is not usually viable. Treatment of contaminated land is altogether a more tricky issue as, if the land is to be reused, this could be an activity requiring a waste management licence and, if the treated land is returned to the land, this could constitute land filling waste under the landfill directive. There are no easy answers as yet to this matter, but suffice to say that the issue of waste is a costly one.

It is unlikely that an average business will have the in-house capability for successful remediaton of the land and handling of wastes.

Therefore, remediation in almost all cases is performed by dedicated land remediation contractors. And there are quite a few out there, most using their own speciality techniques. This means, availability and costs permitting, it should be no problem finding a contractor capable of remediating your land in accordance with your remediation scheme

Why can things go wrong ?

If all this is quite straightforward, why can things go wrong – and they have. The land gets identified as being contaminated, a remediation scheme is established and a competent third party comes along and cleans up. It seems simple, but if the wrong remediation technique is used or the scale of contamination is not properly understood, then there is the risk that the land will not be remediated to a standard suitable for use. The likelihood of this occurring is greatly reduced if a comprehensive site investigation programme is undertaken, and the results are incorporated into the remediation strategy, agreed not only by the appropriate person and enforcing authority but also by the land remediation contractors themselves.

That is not to say that the contractor is not capable of getting things wrong. Poor application of the remediation technique, whether as a consequence of inexperience or incompetence, will have the same result effect as not scoping the work accurately, i.e. failing to return the land to a suitable condition.

So what should you expect from your land remediation contractor. Key things to look out for in a competent and well-resourced contractor so that you can also discharge the duties under he Construction (Design and management) Regulations vis-à-vis appointments, are:

• Proof that they have in-house expertise to undertake site investigation (desk top and intrusive)
• Access to equipment and waste management licence for treating contaminated land on-site
• An approved disposal route for disposing of contaminated land as waste off-site
• Sufficient liability insurance coverage
• A sound health and safety and environmental policy
• A clean regulatory history
• A good track record in the provision of their services

The current reclamation and remediation situation in the UK reflects the wider environmental concerns and priorities arising from the re-use of contaminated land with, in particular, the statutory controls now in force in relation to the protection of what are defined as “controlled waters”. This definition includes all inland waters such as aquifers, watercourses and ground waters, and therefore all reclamation and remediation projects must have regard to the effect of such proposals upon controlled waters.

As the old saying goes, ‘you get what you pay for’, and from the outset land remediation is a costly activity. A range of grants is currently available for the remediation of contaminated land but most governmental money is provided to local authorities and Regional Development Agencies (it is the London Development Agency that has taken on the task of cleaning up the Olympic Park site) and therefore it is up to them how to spend it.

Businesses can claim relief from corporation tax if they clean up contaminated land. In fact businesses can claim tax relief of up to 150% of the clean-up cost. Relief is provided if the land was acquired by the business to carry out its trade, and at the time it was acquired all or part of it was contaminated. Relief is not due if the contamination is a direct consequence of the businesses activities, to ensure that the polluter doesn’t get paid! If you are about to enter this mucky arena, your operator could now apply for a Mobile Treatment Plant Licence (MTPL) through a new process designed to be consistent, speedy and flexible. Although remediation seems expensive, the benefits can be huge, as large areas of ugly, despoiled land are returned to beneficial use with values to match.

Published: 10th Mar 2006 in AWE International