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Building on contaminated land

by Dr Bill Baker

For many years successive governments have recognised the need to tackle the problems of regeneration of the large tracts of derelict land in our urban areas which are a legacy of our industrial past. There have been many successful initiatives which have transformed some of the most difficult sites into new developments for industrial, commercial and residential purposes, which are an important part of our modern communities.

On occasion, however, the reclamation and redevelopment of contaminated sites has been constrained by an atmosphere of uncertainty, leading to mistrust by the end user and the local community. There has also often been a lack of enthusiasm on the part of some developers to get involved in developments involving expensive remediation, and concern about the extent of residual liabilities should things go wrong. This situation has had a significant adverse effect on the progress of the government’s “brownfield” housing initiative which is intended to promote the regeneration of urban and inner city areas and reduce the pressures on the progressive development of the countryside. The Urban White Paper (1) and the Spending Review 2000 (2) have set a target that 60% of new housing should, by 2008, be provided on previously developed land and through the conversion of existing buildings. Furthermore, a target for the rate of reclamation of brownfield land has been set to exceed 1,100 hectares per annum by 2004. This should have the effect of reclaiming 5% of current brownfield sites by 2004 rising to 17% by 2010. Such challenging targets mean that we must seek to overcome many of the barriers to redevelopment which currently exist.

Facing the Challenge
There are many barriers to the achievement of this target often associated with inconsistent application of technical guidance and regulation. Primary control of the redevelopment process lies with the Planning Authorities, the developer and their consultants. The Environment Agency regulates remediation processes, and is a statutory consultee on planning applications, and therefore has an indirect influence on the regeneration of brownfield land. The problems of public perception of the risks associated with living on a previously contaminated site arise from a general widespread lack of understanding of the complex multidisciplinary problems involved in the management of contaminated land and its remediation. Whilst the public cannot reasonably be expected to be aware of the complexity of the subject, it is vital that regulators, developers, contractors and consultants are fully aware of the issues. This is not always the case, and can lead to major problems in developing such land.

Research has revealed that most householders, both owners and tenants, living on developed brownfield sites, were not aware of their situation because of a widespread reluctance on the part of Housing Associations, local authorities, developers and builders to share this information. (3) This can result in substantial concern to residents, when information on the history of a site is released later in an uncontrolled way. Significant social and economic disadvantage can be suffered by a householder when the prospective purchaser’s solicitor’s questions relating to the site’s previous use and remediation cannot be satisfactorily answered from the local authority records. In contrast, an open policy on information provision has avoided such problems, and led to much smoother sale and insurance of properties.

Local authorities operate the Planning Regime and have relied upon the use of the ICRCL Guidance (4), introduced over twenty years ago, in 1978. This provides “tentative” guideline trigger values for the level of various contaminants in soil that can be tolerated in the context of domestic housing and other sensitive developments. The generally inconsistent and uncritical way in which the guidance has been applied in the past has often led to conflict between developers and regulators, with many instances of over-prescriptive remediation being demanded by the regulator to ensure public safety. In contrast, there has sometimes been an uncritical acceptance of the recommendations of the developers’ consultant for inexpensive but inadequate remediation which is not sustainable and may become unsafe.

This overall situation emphasises the need for new technical guidance for contaminated land, to assist those involved in the business of house building and redevelopment of sites affected by contamination. Such a programme of guidance has been in development for a period of years and is nearing completion, with publication expected in 2001. Whilst the planning regime remains the primary means of ensuring that land contamination is dealt with properly when a change in use is proposed, the year 2000 saw the introduction of the new Part IIA regime for dealing with contaminated land where it is found to be unsuitable for current use (5). This regime complements the planning system insofar as Part IIA deals with current use, and planning with proposed changes in use. One area of technical guidance which has already been published in support of redeveloping brownfield sites is the new Guidance for the Development of Housing on Land Affected by Contamination (10), published jointly by the Environment Agency and the NHBC.

The new Contaminated Land Regime The implementation of the new regulatory regime represented by Part IIA of the Environmental Protection Act 1990, (introduced by the Section 57 Provisions for the Regulation of Contaminated Land of the Environment Act 1995) (5), in April 2000, provides an effective means of dealing with those sites which are not captured under planning, primarily because no change in use is proposed. Its introduction completes an effective framework for the remediation and control of land contamination. It is based upon a sound set of principles, which include: “suitable for use” standards of remediation, the “polluter pays” principle for the allocation of liability, i.e. assessment of contamination by a risk based approach, and the achievement of reasonable solutions, greater consistency and sustainability through policies of consultation, co-operation and partnership.

The central theme of the new regime places great emphasis upon a system of risk assessment subject to open scrutiny as promoted in the associated statutory guidance (6). It is supported by a growing volume of sound technical guidance on assessment, remediation, etc. from DETR and Environment Agency sponsored research. This will clearly lead to greater consistency, the promotion of best practice, and a greater level of confidence in the systems of remediation and their durable safety. By following policies of openness and transparency, developers should gain more widespread understanding and acceptance for brownfield development by potential purchasers and householders.

Essential to underpin these changes in the future will be the development of the Model Procedures for the Management of Contaminated Land (7). They incorporate existing good technical practice, including the use of risk assessment and risk management techniques, into a systematic framework for identifying, making decisions about and taking appropriate action to deal with contamination, in a way which is consistent with UK policy and legislation. Tools have been developed to assist regulators and developers alike in the difficult decision-making process. Amongst these is the Contaminated Land Exposure Assessment (CLEA) risk assessment model (8), which uses the toxicological information for particular contaminants, information on the contaminant levels in soil, an analysis of the potential pathways for a contaminant to cause harm to the human condition in the sensitive context of domestic housing, and probability theory to enable site specific risk assessment to be carried out. Its most important application is the development of new more robustly researched “Guideline” values (9) which replace the old ICRCL “tentative” figures.

There are other sensitive targets, apart from housing, that will also need to be evaluated for potential risk. They include the local water environment, and tools have also been developed to assist in the assessment of risk and the need for remediation. Whilst the new regulatory system applies primarily to the current state of land, the basic principles of risk assessment are equally applicable to all development situations and their application will ensure successful and sustainable regeneration of brownfield land. The local authority system of inspection of land which is an integral part of the new legislation will provide the planners with much valuable information which will help in avoiding the mistakes of the past, whereby planning approval was often given for development in ignorance of the potential problems of contamination.

Housing Development Guidance
The need for guidance, specifically for the development of housing on land affected by contamination was recognised some years ago by the DETR following confirmation of the UK policy approach to legislation in this area. A comprehensive guidance document was drafted which was based on the application of principles of the risk assessment and management as advocated in the Model Procedures for the Management of Contaminated Land, the CLEA model and other relevant guidance, published and in preparation. The volume of such guidance developed in recent years by the Agency, the DETR, CIRIA, BRE and others is formidable. The Agency, in close partnership with the NHBC, using CES Ltd as consultants, has reviewed this guidance and, drawing from the relevant sources, has thereby developed a used-friendly guidance document specifically designed for the use of housing developers, house builders, housing associations, local authorities, regulators and consultants.

The objectives of the Guidance for the Safe Development of Housing on Land affected by Contamination (10), are as follows:

  • to support the “Brownfield” housing initiative; • to overcome the wide inconsistencies in the application of current guidance;
  • to overcome the problems of public perception and improve communication of information;
  • to point the developer and house builder and their advisors towards appropriate solutions and best practice

Within the guidance document, the “Model Procedures” have been translated into a series of stages or steps in the process of housing development from initial consideration of a project to the completion of remedial works and its validation. There are eleven practical steps incorporated in the four main stages involving the two phases of Risk Assessment, the Evaluation and Selection of Remedial measures, and the implementation of risk management as described below: –

– Risk Assessment covers Hazard Identification whereby a desk study and site reconnaissance is used to gather information about previous contaminative uses, general physical and geological conditions, so as to gain a preliminary understanding of potential risks associated with the identification of the contamination likely to be present on the site. (steps 1 & 2)

– This is followed by Hazard Assessment, which involves the identification of receptors and pollutant linkages likely to exist on the proposed development, and may involve initial investigations and analysis to provide a preliminary indication of the potential for risks to health and the environment through the development of a conceptual model. (steps 3 & 4)

– The Risk Estimation stage includes the design and execution of a detailed investigation and analysis to collect sufficient data to allow estimation of the risks that contaminants may pose to receptors, e.g. residents, under the conditions of the development. (steps 5 & 6)

– In the process of Risk Evaluation all available risk-based information is reviewed to decide whether the estimated risks are unacceptable, taking into account their nature and scale, and any technical uncertainties which may be associated with the risk estimation process. (step 7)

– The use of models and detailed guidance to assess the risks to human health and other receptors such as controlled waters, ecological systems and building structures and services, will be applicable at this stage.

– The Evaluation and Selection of Remedial Measures procedure covers the activities where decisions are made on the most appropriate form of remedial measure to control or reduce unacceptable risks. It involves the review of all available data to ensure that there is sufficient information to carry out the evaluation and selection process. Potentially suitable remedial options are then identified, and the alternative options subjected to detailed analysis. The preferred remedial strategy is then selected, based on the most appropriate and cost-effective of the available options. (steps 8 & 9)

– The Implementation of Risk Management Action involves the design of the detailed development plan, submission along with all supporting documentation to the approval authority, execution of the remedial work and its post development validation. There may also be situations demanding long term monitoring or maintenance of certain measures which are vital to the on-going effectiveness and durability of the development. (steps 10 & 11)

The level of expertise and understanding among housebuilders and developers varies considerably, and the stages in the process where the need for specialist advice is likely to be required is highlighted in the guidance.

Throughout the document there is a strong emphasis on early and frequent consultation with all the regulatory authorities to ensure that a common objective is agreed and that at every stage there is adequate information and supporting documentation to demonstrate the overall acceptability of the development. The importance of consultation with the local community is stressed. This should ensure that all information, which is relevant to the development, is available in an open and transparent way to all interested parties, in the spirit of the new regulatory regime, so that the disadvantages of the present system, which often leads to blight and suspicion can be avoided. The recently published guidance Communicating Understanding of Contaminated Land Risks from SNIFFER (11) is recommended to assist in the most difficult area of public consultation and trusting relationships.

The Way Forward
The final DETR Circular incorporating the Statutory Guidance and Regulations associated with Part IIA regime was lodged with the Parliamentary process, and implementation was effective from April 2000. The document also includes a Statement of Government Policy and a treatise on the way in which the new regime will fit in with the planning regime and other existing environmental legislation, which has relevance in this field.

The success of the new regime will be dependent upon the regulators, and especially the local authorities, consistently requiring a high standard of site assessment and risk based management from the developers and their consultants in the redevelopment of sites affected by contamination, especially in the context of housing. This will involve the application of a risk based approach, in accordance with guidance and best practice, to the assessment of sites, which will inform the remediation strategy, the implementation and post development validation, all in an open and transparent way, in line with the ethos of the new technical guidance and policy approach. This will in turn increase the level of confidence which all stakeholders can have in the redevelopment of such sites, and avoid the potential for blight and the social and economic disadvantage which has arisen when a robust technical approach and adequate regulatory control has not been exercised.

It must be recognised that this vision can only be achieved through effective training for both the regulators and the private sector, in the application and acceptance of the risk-based approach and its many advantages to the management of contaminated land.

In particular it is anticipated that the implementation of the new regime, the acceptance of the risk based culture and the new Housing Guidance document, will together play an important role in the achievement of the Government’s “Brownfield” Housing Initiative objectives.

The Agency continues to sponsor a significant programme of work in the field of contaminated land, and has established a centre of expertise at the Midlands Region Headquarters at Olton, Solihull. The National Groundwater and Contaminated Land Centre exists to promote research in new techniques of assessment and remediation and to support the Agency in its regulatory roles in this area

The Agency looks forward to playing an important role, in partnership with others, in encouraging and promoting the regeneration of contaminated land, and bringing it back into beneficial use, as a contribution towards the realisation of the Agency’s vision of “A better environment in England and Wales for present and future generations”.

Dr Bill Baker is National Capital Projects Manager, Contaminated Land at the Environment Agency, National Groundwater & Contaminated Land Centre, Solihull.

1. DETR (2000) Our Towns and Cities: the Future. Urban White Paper
2. H.M.Treasury (2000) Spending Review 2000
3. Syms, P., (1997) “The Redevelopment of Contaminated land for Housing Use”. A research project for the Joseph Rowntree Foundation by the School of Urban and Regional Studies, Sheffield Hallam University. The Incorporated Society of Valuers and Auctioneers.
4. Interdepartmental Committee on the Reclamation of Contaminated Land(1987). “Guidance on the Assessment and Redevelopment of Contaminated Land”. ICRCL 59/83 2nd edition.
5. Government of Great Britain (1990) Environment Protection Act 1990: Part IIA, Contaminated Land, (inserted by section 57 of the Environment Act 1995).
6. DETR (2000): DETR Circular 02/2000, ” The Environmental Protection Act 1990 -Part IIA – Contaminated Land “. The Stationery Office.
7. DETR and Environment Agency (2000), “Model Procedures for the Management of Contaminated Land”, Research Report No l l, DETR – in press
8. DETR and Environment Agency (2000), The Contaminated Land Exposure Assessment Model (CLEA), Technical Basis and Algorithms”, Contaminated Land Research Report No 10, DETR – in press.
9. DETR and Environrnent Agency (2000), “Guideline Values for Soils”, Contaminated Land Research Report, GV, DETR – in press.
10. Environment Agency and NHBC (2000), “Guidance for the Safe Development of Housing on Land Affected by Contamination”, R&D Publication 66. The Stationery Office
11. Scottish and Northern Ireland Forum for Envirormental Research (SNTFFER) “Communicating Understanding of Contaminated Land Risks”, Technical report 142

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