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Housing on used sites

AGS position paper on the implications for geotechnical and geoenvironmental specialists of redevelopment of brownfield sites for housing.

Increasing pressure towards the reuse of previously developed land for housing is evident.

This paper examines the issues associated with the redevelopment of previously used ('brownfield') sites for use as housing and the likely implications for geotechnical and geoenvironmental specialists who are becoming increasingly involved in such projects.

Policy The Government's White Paper, Planning for the Communities of the Future , sets a target for 60% of new homes to be built on brownfield sites by 2016. The objective is to address the projected demand for housing, while also protecting the quality of people's lives and ensuring stability in the housing market.

Housing growth has been forecast not just as a result of overall growth in population but also due to significant social changes such as an increase in life expectancy, divorce and separation rates and a growth in single person households. The Government has estimated that there are approximately 1.3 million residential and commercial buildings currently empty and that it is projected that 3.8 million households will form from 1996 to 2021.

The Deputy Prime Minister, John Prescott, asked Lord Rogers to set up the Urban Task Force in order to research the causes of urban decline in England and to recommend practical solutions to turn our cities, towns and urban neighbourhoods into places where people actively want to live, work and play. The Task Force report, Towards an Urban Renaissance , was published in June 1999. This report recognised the importance of brownfield land development in urban areas as a method of preventing fragmentation of the city and erosion of the countryside.

Legal background The assessment of proposals for housing on brownfield sites is often a complex matter. At present assessment of the significance of ground contamination is made with regard to both existing law and the new contaminated land regime [Regulations made under Part IIA of the Environmental Protection Act 1990 (inserted by Section 57 of the Environment Act 1995)], implemented in April 2000.

The assessment of contamination is a material planning consideration and a Building Regulation requirement. The local planning authority will determine an application on the basis of information regarding possible contaminated sites available to it. Often, in discussions with the local planning authority prior to the submission of an application, potential contamination will be brought to the attention of the developer. The applicant is then able to take into account the full requirements of the planning authority while designing the scheme/application.

Planning authorities will also grant planning permission for sites where there is a suspicion of contamination. However, a condition will be attached which does not permit development to commence prior to a site investigation and full assessment. In this case a separate notice is often issued to the applicant informing him that the responsibility for safe development and secure occupancy of the site rests with the developer.

Under the Building Regulations 1991 district councils are responsible for enforcing certain requirements which ensure the health and safety of persons in or about buildings. When there is a proposal to build on a contaminated site the district council would have to enforce requirements such as that the ground to be covered by the building is reasonably free of biodegradable matter capable of producing gas and precautions are taken to avoid danger to health caused by substances on or in the ground to be covered by the building. Should an incident arise where the district council has failed to take reasonable care then they may be held liable for breach of statutory duty or negligence.

Under the new contaminated land regime potential liability associated with statutory 'contaminated land' rests initially with the polluter (the Class A person) or, in default, with the owner or occupier (the Class B person). A number of other persons can also assume the responsibilities of a Class B person. This new regime deals with current contamination/ pollution. The planning system will continue to deal with the implications of contamination on planned new developments.

When acquiring a site, and in the absence of contractual provisions to the contrary, the law would find it reasonable that a developer made itself aware of ground contamination issues whether or not it has investigated the site. Even if the contractual indemnity exists for the benefit of the developer this is unlikely to affect his primary liability to a regulator or third parties. The guidance for the new regime suggests that in recent and future transactions between large commercial organisations the ability of the purchaser to undertake an investigation will raise the presumption that the site was sold with relevant information as to contamination.

A developer will be responsible for any contamination created on site during construction, or for contamination mobilised by operations on a site. In addition a developer will be liable for damage occurring during this period of ownership where a problem was known to exist but nothing was done about it.

Both under statute and common law the liability remains indefinitely so long as a regulator or third party claimant can attribute a problem to a developer's period of ownership. Obviously as time goes on it becomes increasingly difficult to attribute a problem to a developer who may have only owned the site for a relatively short duration. Under the new regime, the original polluter of the site may escape liability because the developer has introduced a more sensitive end use or has created a pathway, and thus in developing the land has brought it under the definition of 'contaminated land'. In such cases the courts are likely to look for ways of assisting residential purchasers if they feel they have been sold sites with incomplete information.

Under Part IIA it is possible that consultants/contractors (professional advisers) could become liable for the costs involved in satisfying a remediation notice (for example if carrying out an investigation created a significant pollution linkage (irrespective of the question of negligence).

Clearly, consultants/ contractors are expected to carry out their agreed services with reasonable skill and care in accordance with standards applied by other reasonably skilled and fully qualified professional advisers in their field. The implication of Part IIA is that even if reasonable skill and care was exercised, but a significant pollution linkage was created, then the consultant/ contractor could become a 'responsible person'. However, under the Statutory Guidance, the consultant/ contractor might be excluded from liability where his client can be identified and located.

Risk assessment The use of risk assessment methodology has become 'standard' practice in the assessment and redevelopment of contaminated land over the last few years and is now 'enshrined' in the new guidance. This process identifies potential hazards on the site (the contaminant sources), assesses the potential for exposure (the linkage between the source and receptor) and the potential significance of exposure. The relationship between the source (land contamination), pathway and receptor is entitled 'pollution linkage'. Land will only be classed as 'statutory contaminated land' by the local authority/ Environment Agency if there is a proven pollution linkage with the potential to pollute controlled waters and/ or to cause 'significant' harm to people or the wider environment.

The assessment of risk in this manner is used to determine the need for and scope of further investigation and/or remediation works. The implementation of such a remedial programme would then allow the potential risks to be reassessed. This should be able to demonstrate that residual risks to future occupiers of the redeveloped sites are at an acceptably low level.

Consideration has to be given to potential liability associated with the short-term ownership and/or occupation of the site and any subsequent long-term implications to the developer or owner. In many cases involving the redevelopment of contaminated land, the local planning authority will have imposed planning conditions relating to clean-up of the site.

A risk assessment can only ever be as good as the data gathered. It is thus essential that data yielded during a site investigation can be trusted, and has been gathered following a rigorous and transparent methodology underpinned by high quality planning, design and implementation.

The regulatory regime

Political pressures on the Environment Agency and local authorities to move away from decision-making involving the cost-dependent principles of Best Available Technology Not Entailing Excessive Costs (BATNEEC) towards a cost-independent assessment based on Best Practicable Environmental Option (BPEO) are increasing.

Some local authorities already have in-house expertise in contaminated land and have developed a considerable track record.

However, some others have had little direct experience and may lack relevant technical skills. Their difficulties are compounded by the lack of agreed standards on both investigation, assessment and reporting (although work has been and continues to be carried out to provide this). The current absence of good practice guidance contributes to significant variability in proposals for redevelopment submitted to the regulators for their approval. This variability adds to the complexities for the regulator, who then has difficulty in understanding what level of detail to expect, and what standard the works should have been measured against. It is imperative to consult with regulators early on in the process and to supply them with sufficient information.

When carrying out their own assessments of proposals there is also a tendency for the regulators to be risk averse - ie to make ultracautious judgements. This is because in the long-term responsibility may fall on them in the future.

Implications for members of AGS

The redevelopment of brownfield sites for housing is set to become an increasingly mainstream part of geotechnical and geoenvironmental specialists' activity. It is clear that the development of contaminated land for use as housing is a very sensitive issue.

It is also clear that success for us as professionals in this area will require an improved awareness and understanding of both the technical issues associated with ground contamination, and the 'softer' aspects such as risk communication. Keeping up to date with both technical guidance and the relevant legislation and regulations is also important, especially as these are predicted to change rapidly over the next few years.

A key lesson from experiences to date is that it is important to 'get it right' at the commencement of a project. There is also a lot that we have to learn to do differently to ensure that we appear credible and trustworthy to both regulators and the public.

All AGS members should be aware that the National House Building Council (NHBC) has produced a new standards chapter, Chapter 4.1, dealing with land quality. The chapter, which deals with both geotechnical and contamination hazards, provides a structure and consistent framework for managing ground conditions and applies to all sites, regardless of their previous history. In addition, the NHBC has extended its warranty cover for all new homes registered after 1 April 1999, to protect the home owner in accordance with anticipated new legislation for contaminated land.

NHBC's initiative facilitates the Government's objectives of safely managing contaminated land and bringing damaged land back into beneficial use.

High standards must be achieved in all phases of the development process. All the various activities in site investigation and risk assessment must be consistent, rigorous and transparent.

The relevance of a risk assessment, no matter how sophisticated it may be, relies upon the validity of the basic data about ground conditions, ground and groundwater chemistry etc. It is therefore fundamental that all of the data obtained from the various phases of site investigation is relevant, accurate, reliable and wholly credible to both developer/owner, regulator and the public.

Efficiencies can often be made by combining geotechnical and contamination investigations.

Carrying out such investigations at the same time can avoid unnecessary duplication of time and costs. A number of work activities and investigation techniques may be common to both types of investigation and if properly planned, can be carried out without compromising the aims and objectives of either. The AGS Guidance on combined investigations will be published later this summer.

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