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  • Writer's pictureAdewole Ademolake

What Lies Beneath: Ground Risk in Property Development – Matt Logan

By Matt Logan - Principal at SLR Consulting


As the saying goes in the context of site redevelopment, 'you pay for a ground investigation – whether you have one or ' not.

The premise is that a poorly or inadequately scoped ground investigation, particularly on more complex sites, can result in risk being pushed further down the programme resulting in higher costs, delays and disputes down the line.

Ground Risk Foreseeability

Unforeseen site conditions cause delay and cost overruns for projects of all sizes. For example, in 2019, Allan Cook, the chairman of HS2 Ltd, blamed (in part) increased costs for the flagship infrastructure project on ground conditions which were "significantly more challenging than predicted. Projects involving the redevelopment of brownfield sites may encounter existing structures or contamination below ground. In contrast, refurbishment projects may discover services not shown on a drawing or simply in the wrong place. Delays can have a debilitating effect on all parties involved, as 'it's often the cause of adversarial relationships, a feeling of apprehension and distrust between the Developer, Contractor and consultants.

While some ground conditions can be ''unforeseen', the reality is that a properly scoped and developed ground investigation will address risks and allow for the management of liability through forward planning, cost allocation, risk registers and contractual agreements on risk apportionment. So if it is this simple, why is a ground investigation sometimes seen as a burden and the scope minimised? A ground investigation completed early should be used as a valuable tool in its own right to inform land purchase, viability, master planning, programming and early identification of areas where potential cost savings could be achieved. The physical identification of services and utilities across at site could have the potential to impact on developable areas and diversions could become costly if not accurately identified and brought through early enough in the design process. Ground investigations add value to projects and do not devalue them.

Tolerance of foreseeability as an aid to establishing the project ground risk profile - Eddleston & Holme 2009

One of the reasons is that ground investigation is often considered a project overhead, typically attracting a fraction of the funding of the overall project spend (typically 0.1 to 0.3% of the total scheme cost). The low level of expenditure on ground investigation fails to recognise the significant inherent risks and the value that a robust ground investigation can bring to the overall project delivery. This disparity was recognised as long ago as 1984 when the National Research Council recommended that a minimum of 3% of the project value be dedicated to ground investigations.

Construction costs within the ground can vary by magnitude, whereas the above-ground construction costs are typically predictable within 5 -10%. The importance of understanding your ground conditions is highlighted by the Institution of Civil Engineers (ICE), who state, "The ground is the place where things are most likely to go wrong during a construction project. The worse the ground conditions, the greater the risk".

Ground Investigation Objectives

One of the other issues possibly not fully understood is that a ground investigation is not just a "ground investigation". There are different needs and drivers – geotechnical, earthworks groundwater, land quality, for example. These may all vary the required scope and, therefore, the technical differences in projects. There are also different phases to site investigation, from a preliminary 'look-'see' with a low density of investigation positions to a more detailed analysis of a higher density, or potentially further investigation to delineate a known area of concern.

Investigation of potentially contaminated sites. Code of practice - Code of practice - BS 10175:2011+A2:2017

In addition, a ground investigation required to get a site through planning may be insufficient to take the site through to detailed development design. The point being that just because a ground investigation has been completed does not mean that 'that's it done and dusted.

Ground Condition Variables

There is no one size fits all approach - and because a specific scope or cost has been achieved on one site does not mean that this will apply to another. It is more complex than this. Every site is different and will have its own unique challenges as many other variables come into play. That is why it is so difficult to put a unit price on a ground investigation. The simple fact is that until you have looked at the site's specifics, such as its geology/groundwater, previous development phases, surrounding land uses and environmental sensitivities, you will not adequately be able to determine the scope. Factor all this together, and it becomes clearer to understand why the scope and costings at one site will differ on a project by project basis.

Understanding some of these nuances are important in identifying how much risk remains uncharacterised and how this should be managed going forward. Donald Rumsfeld's now-infamous "known knowns, known unknowns and unknown unknowns" phrase completely resonates with ground risk practitioners as there are general risks we know about and those we think we know about. Still, others can be unexpected. It is these risks and uncertainties that a ground investigation should try to address.

Why are ground risks ignored? It may be because these complexities cannot be seen at a surface level, therefore not fully understood. Most people believe that such risks can be overcome through engineering or remediation, even as the information on which the design is based may be wholly inadequate. This lack of knowledge of the potential variability of the scope could have significant implications later in the construction programme. Perhaps some may prefer not to know what issues they are dealing with, turn a blind eye and allow someone to deal with them later, look to pass the risk on to another party or even potentially not have the know-how or foresight to deal with them.

Ground Risk Identification & Risk Allocation

There is a balance to be found between cost and value and expenditure vs residual risk. The risk of something "unexpected" being found in the ground can be reduced by ensuring that the ground risk practitioner has appropriate experience. Still, it is worth considering whether the specialist has the expertise to deal with what might be found, rather than only having knowledge of what is expected to be found. In other words, bear in mind that the site might not be as straightforward as it looks. And because a practitioner may be a good contamination expert does not mean they are a geotechnical engineer and vice versa.

NEC Engineering and Construction Contract (ECC) allocation of risk

So, why should you invest in ground investigations? The answer is simple, reduce risk, lower construction costs and provide greater programme certainty.

  • Proactive Management. Early identification of risks allowing proactive management of ground conditions through informed design and feasibility assumptions. Even something as simple as placing low sensitivity structures in areas of the poorest ground conditions, with high sensitivity structures located in the lowest risk areas.

  • Sustainable materials management. Understanding ground conditions beneath the site can allow for the most sustainable viable solutions for the proposed development allowing materials reuse and retention onsite to be maximised and offsite disposal minimised.

  • Improved efficiency of design. Where designers are faced with high levels of uncertainty, they are forced to compensate for the lack of a robust ground model with conservative design assumptions, which can lead to significant over design of remediation systems or building structures.

  • Optioneering. Better information and the earlier it is available allows time to seek and work through options that will provide the project with its optimum solution. Leaving it late in the programme to work through design solutions narrows down option availability which may not be the most cost-effective, sustainable or innovative.

  • Risk reduction/improved cost forecasting. The earlier risk issues are identified, the earlier they can be managed through the lifetime of the project. It can also assist in contractual risk apportionment, transfer and management of liability, control of cost expenditure and finance provisioning.


As I have mentioned, the earlier a ground investigation can be undertaken in the programme, the better the project will be for it. However, how early is early?

Ideally some work should be done pre-planning during RIBA stages 1 and 2, and which should at least include a desk based review, site walkover and generation of a risk register. If the site is of a low contamination and/or geotechnical risk then this should be sufficient to obtain planning. Nevertheless, it is recommended at this stage that if no site-specific ground condition information is available then an exploratory ground investigation is undertaken to baseline conditions and allow outline characterisation to take place and identify potential early stage risks. Further detailed work could then follow at later stages. The more complex and contaminated a site is, then ground investigation is more likely to be required anyway to support the planning application.

Funding may be a constraint prior to planning being obtained and therefore it is recognised that the cost outlay for a ground investigation may not be forthcoming if it is not a planning requirement. Whilst this may be the view held by commercial stakeholders, as explained in this blog, this may result in greater cost risk further down the line. Without doubt, for the more complex sites then a ground investigation is recommended prior to planning to being obtained to inform potential viability, masterplanning, optioneering and risk forecasting.

Once planning is obtained, ground investigation becomes a pre-commencement requirement to inform detailed development design; earthworks; infrastructure provision; constraint removal and remediation design to inform the enabling and subsequent construction works at RIBA stages 3 and 4. Should no prior ground investigation have been completed, and issues are identified at this stage, the ‘surprise’ has the potential to impact on programme, increase cost and design if not previously considered or adequately accounted for. It is therefore recommended that a ground investigation is completed as soon as funding can be released once planning has been obtained, if it is this reason why it has not been completed earlier in the project lifecycle.

From a transactional perspective, if acquiring a site then it is imperative that the desk based review and site walkover is undertaken pre-purchase. Depending on what this then identifies as the key risks, then a ground investigation may be required to quantify these potential liabilities. The risk appetite can vary between individuals and organisations; and therefore it is what is needed to provide potential funders, legal advisors, purchasers and other stakeholders with sufficient due diligence information on which to base their decision on whether to proceed with the acquisition or not. As ever with property transactions, the caveat emptor or ‘buyer beware’ principle holds true.

Ground Risk Management

Some simple steps can be taken to managing ground risk as part of any development project, as seen below:

  1. Develop a good conceptual understanding of the ground model through desk-based resources and site walkovers to identify geological and groundwater conditions and potential historical uses that could impact its ground conditions.

  2. Take a staged approach to ground investigation to move through planning and forward funding stages before progressing to more detailed analysis for development or land remediation design.

  3. Understand what you are trying to achieve or the information you need to get as part of each phase of ground investigation.

  4. Where possible, complete the ground investigation as early in the programme as possible to assist in 'de-'risking' and cost allocation through risk registers.

  5. Where poor ground, constraints or contamination is found, then begin to consider options early at outline stages before any design commences and identify potential cost and programme outcomes.

  6. Where the site is particularly complex, then potentially engage early with a contractor.

  7. Identify how the risk will be managed and apportioned through the building contract.

  8. Set out a straightforward programme of work so that information is delivered well in advance of design considerations to allow for optioneering.

  9. Identify residual potential gaps in risk or liability that can be flowed throughout each stage of the project and how these will be managed.

  10. Communicate risks to all parties so all are aware of the complexities and issues that need to be dealt with.

AGS Quick Start Guide to Contaminated Land Investigation- August 2011


In summary, risk can be managed, minimised, shared, transferred or accepted, but it cannot be ignored. During the construction process, ground risks may manifest in increased expenditure and/or delays to the programme. However, where the ground conditions are robustly characterised, and an appropriate risk register can be developed, proportionate risk allowances can be set, providing viability on likely expenditure and potential programme delays. Furthermore, a thoroughly scoped and well-executed ground investigation early in the programme may save you contractual and cost heartache further down the line. And, as the saying goes, 'you pay for an investigation – whether you have one or 'not'.

About writer:

Matt is a Land Quality expert specialising in the planning and redevelopment of difficult and complicated brownfield sites. He works with stakeholders who have an interest on acquiring, developing or selling of land and property - investors, developers, contractors and planners – helping to de-risk sites, quantify potential liabilities and removing blockages well before they have the potential to threaten a project. Matt is often brought in by clients where they have discovered that contaminated land issues are more complex than originally thought or where something has already gone wrong. However, he can provide the most added value to your project as part of your team from the very beginning. He is a chartered geologist and Specialist in Land Condition (SiLC) with over 20 years providing land quality services. He can support you with your development and regeneration projects, working as part of your team whilst providing specialist services to ensure ground related issues are properly assessed and managed to meet the development needs, adding value, providing efficiency savings and ensuring excellence as standard. Please do get in touch for a 15 min chat with Matt if you have ground related issues you may need help with on your scheme.

Useful Resources:

  • A guide to small brownfield sites and land contamination - CIRIA C773

  • Investigation of potentially contaminated sites. Code of practice - Code of practice - BS 10175:2011+A2:2017

  • UK Specification for Ground Investigation, Second edition – Institution of Civil Engineers (ICE)

  • Clayton, C. R. I., 2001, Managing Geotechnical Risk : Improving Productivity in UK Building and Construction. Institution of Civil Engineers/DETR, Thomas Telford 2001.

  • Guidance on dereliction, demolition and remediation costs – Homes & Communities Agency (HCA)

  • Association of Geotechnical and Geoenvironmental Specialists (AGS)

  • NHBC



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