A good understanding of the risks and liabilities associated with the subsurface is critical, and can often have a dramatic affect on the profit margins for a project. It is therefore paramount that developers sufficiently understand the implications of the ground conditions beneath a site at each step in the project lifecycle. Gareth Owen of ESI Ltd looks at some of the environmental issues to take into consideration, and discusses the benefits of a close working relationship between developer and advisor in managing the balance between cost and certainty as a development progresses
Ground conditions are fundamental to successful development on any site, and in particular in brownfield regeneration projects. Developers can never know for certain the ground conditions without undertaking a degree of investigation before laying the foundations. Both natural and man-made aspects can affect the land condition, its chemical suitability and its ability to suitably support foundations. These can range from relatively minor risks right through to major issues that could cause structural failure, pollution of the environment, or serious health hazards to both construction workers and future occupants. This in turn poses a series of potential ownership liabilities under both contaminated land and health and safety legislation, as well as a significant cost and programme risk to the development, posing a number of hurdles in the form of outline and reserved matters planning obligations.
Land contamination is a significant issue that can affect the building process and across the UK it’s estimated that around 100,000 sites are contaminated through previous use, such as industrial processes, mining, and waste disposal. Even if they’ve ceased operation, waste materials and residues can still be present in the land and groundwater. For the vast majority of brownfield sites, the planning process is used by regulators as a tool to bring such sites back to a standard that does not pose undue risk to the environment and is suitable for use under the chosen development form.
It is important that soils, groundwater and soil gases are all properly investigated and assessed on brownfield sites, as they may all impact on construction workers, future site users, buildings and the wider environment. In addition is something that is often overlooked – the potential cost implications of the disposal of contaminated soils from development sites, as this can often lead to substantial punitive costs if not identified and managed from an early stage.
Ground stability and strength is another matter that must be explored. Geotechnical risks that can arise include anything from unstable or weak ground to mining and sinkholes, and could pose a major risk to the building and its stability. The degree to which ground improvement is needed, and the type of foundations required, are often key cost considerations in determining the feasibility of development on difficult sites.
In addition flooding and drainage is often a great concern for developers, not only impacting on the overall planning process but also having the potential to alter the build, and a flood risk assessment is required for any planning application where a site is defined by published mapping to be at risk. Considerations here are twofold, and developers should take into account both the risk to the site from flooding and the risk that development of the site may have in causing flooding elsewhere. Increasingly it is the case that these issues are intrinsically linked and a detailed understanding of their interrelationship and their implications on the form and commercial elements of a development can provide substantial benefit. These issues are often complex and involve a considerable cost outlay to characterise.
An effective balancing of cost and certainty is therefore of paramount importance in guiding the developer through from project inception to build, and while it would be ideal to be able to fully characterise all potential ground condition issues from the outset, to do so would entail a prohibitively high spend at a time when commercial, political, and planning matters may render such outlay speculative. A valuable – but often overlooked – skill in providing advice on ground conditions is therefore the ability to tailor the investigation and assessment of such issues in order to focus on matters pertinent to each point in a project cycle.
For instance, a pre-purchase assessment only needs to focus on the issues that pose potentially significant cost and programme implications, and may impact on any commercial transaction for the site. In most instances, a desk study might be sufficient for this, but some limited intrusive investigation involving trial pits or boreholes may be prudent. An iterative approach should then be employed in furthering the scope and resolution of investigation and assessment, through outline planning and detailed design stages. At each stage the statutory and planning obligations of the developer, and their cost-planning and programme requirements are balanced against budgetary constraints.
A competent and experienced geo-environmental organisation can provide clear and pragmatic advice and essentially assist in ensuring safe, compliant, and above all, cost effective development. Such advice is best sought at project inception, as obtaining expert guidance at this stage will enable early characterisation of risk and liabilities, and will maximise the ability to review options early in the development process, hence maximising opportunity.