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TECHNICAL NOTE Study of the benefits of ICE Site Investigation Steering Group documents: 10 years on

By SJ Everton, head of geotechnics, Jacobs and BT Diffin, University of Surrey (formerly of Jacobs).

In 1993 the ICE's Site Investigation Steering Group published four documents which, along with a marketing campaign in industry magazines and forums, were intended to educate the industry, clients, consultants and contractors about the value of properly implemented geotechnical investigations. The documents were:

Without site investigation ground is a hazard - the 'pink book';

Planning, procurement and quality management - the 'blue book';

Specification for ground investigation - the 'yellow book'; and

Guidelines for the safe investigation by drilling of landfills and contaminated land - the 'grey book' Ten years on from their publication, the quality and value of site investigations (SI) is still questioned.

Driven by client requests, and as part of a programme of quality assurance and Health & Safety Executive supply chain management, a research project was undertaken (Diffin, 2004) to identify contemporary issues in the SI industry. Interviews were conducted with SI contractors, structural and geotechnical consultants, clients and specialist geotechnical contractors.

Interviews were chosen over questionnaires because of their flexibility.While it is recognised this does not constitute a representative statistical sample of the industry, it was considered more appropriate to find out what the general problems were from the thoughts and opinions of people dealing with them every day. Main concerns are shown in Table 1.

General issues Clients Clients said funding for an SI could be difficult to secure in the early stages of a potential project.

Accurate forecasts of the cost of SI helps ensure funding can be allocated. One way of making sure the SI is less likely to over-spend is by a lump sum contract, requiring the contractor to carry financial and technical risk.

Clients often have to respond to a quickly changing business environment. To make important decisions that will affect the project, it is important that the interpretative report contains correct information and is obtained early on in this process.


Despite knowing the benefits of good quality desk studies, nearly all consultants felt they were frequently inadequate, as insufficient time was allocated to them. Most felt the time constraints were unrealistic, and therefore the initial and important stages of procuring an SI were often omitted.

Geotechnical consultants expressed concern about the apparent trend towards using simple investigation methods such as window sampling. This will inevitably have an effect on the sample quality and therefore accuracy of results, although the technique is very useful on confined sites.

Site investigation contractors

Concern was common regarding the widely varying quality and lack of consistency in the specifications and bills of quantities received.

Smaller contractors, often dealing directly with the client or a nongeotechnical professional, are often subjected to unrealistic specifications, budgets and time frames.

As the contractor is often working under a lump sum basis, it is forced to carry these risks.

Contractors said while some prices had remained in line with inflation, other areas had not seen a significant increase over the past 10 years.

Smaller contractors find recruiting and maintaining suitably qualified members of staff difficult.With rates generally staying below inflation of most items of work, there is little money available for retention salaries or bonuses.

While various companies had been working on improvements in insitu testing, it was reported that there is no obvious demand for new technology for drilling. This correlates with the current trends of selecting low-tech equipment, such as window samplers.

Specialist contractors

Specialist contractors continue to show concern about their lack of involvement in the design of SIs and felt that if they had an input then money and time would be saved. Often, information that may be required for construction may be missing as the author of the interpretative report may not have been aware of elements essential to the technique involved. Contractors would therefore like to be involved in the writing of the interpretative report.

Popularity and use of the SISG documents

At the start of each interview, practitioners were asked if they knew of the four SISG documents, and if they used any of them. Results are shown in Figure 1, which shows interviewees have a reasonable level of awareness of the documents, but the level of use is low.

Analysis showed clients were not aware of any of the documents whatsoever and therefore do not use any of them in procurement.

Consultants and SI contractors use the pink book to inform clients of the risks involved with the ground. Historically, the grey book was used in a similar way.When questioned why they do not use the grey book, most said the information in it has become outdated.

The yellow book was used mainly for the template bill of quantities but most companies now had electronic versions of this and therefore did not need the book for detailed reference.

The most interesting finding is that the blue book, while aimed primarily at SI designers, is used by none of the practitioners questioned. This was attributed to the book's content, which does not have to be referred to continually, unlike the yellow book.

Use of geotechnical advisers

The SISG documents recommend an adequately qualified geotechnical adviser (GA) should be associated with any project interacting with the ground, to ensure the correct planning and design of a ground investigation, and that the investigation is adequately supervised to ensure it is carried out correctly.

The process of appointing a GA is dependent on the principal technical adviser (PTA) knowing their own abilities. PTAs are normally chartered engineers or architects and their experience of geotechnical issues may be significantly less than that of an average geotechnical engineer. If the PTA is overconfident in their own abilities, the risks associated with unforeseen ground conditions is increased.

Most practitioners knew about the role of the GA, but when asked if they actually specify or use a GA on a project, they said they do not specifically use or formally act as one at all. As clients were unaware of the documents, they were not appointing anyone to this role either (Figure 2).

It is the duty of the GA to advise the client about the benefit of desk studies; yet GAs are rarely used. This can lead to misinterpretation of requirements, so it may meet the needs of an individual party rather than the overall project. Consultants and contractors both agree the time allocation for an adequate desk study is often insufficient. As a result of time constraints and lack of understanding, desk studies are often inadequate or not done at all.

Client role

The pink book was aimed specifically at clients. If clients understand what the PTA and GA are telling them, it will increase awareness of the risks associated with the ground.

However, as some clients have little interest in geotechnical issues, trying to explain the complexity and justification of a problem can be difficult. 'Investigating attitudes' (GE November 98) reported that some clients are 'more interested in collateral warranties rather than content and recommendations made in the report' All consultants questioned considered a geotechnical risk register was an easy and successful way of communicating potential issues to clients. Where risk registers were used, the financing and design of the SI was less difficult. Consultants attributed this to clients having a better understanding of why they needed to investigate certain areas of the site to reduce the risk.

None of the clients questioned knew of or used the documents. Users of the pink book were the geotechnical consultants and SI contractors who used images and extracts to highlight potential problems to clients.

It can be questioned whether the pink book reached its target audience. Alternatively, the audience was reached 10 years ago, but clients and their staff have changed, moved on, or have employed younger staff who were not in the industry a decade ago. As the SISG documents have not been readvertised or disseminated, today's clients may not be familiar with them.

This may be a similar situation for consultants and the investigation contractors and may contribute to the shortfall in knowledge and use of the documents apparent in Figure 1.

Training and qualifications

Atkinson (2004) identified two important and contemporary issues with ground engineering. First, about two-thirds of all ground engineering is done by non-geotechnical engineers; and second, the cause of most ground-related problems was to do with the competence of engineers and their education and training.

Use of the most appropriate and trained staff was identified by the SISG documents as being an area that could improve the quality of SIs.The pink book introduces the concept of the PTAs and GAs being the most important people in an SI, and that appropriately trained staff should be used whenever possible.

It also introduces the idea that perhaps site supervision is not up to standard and improvements could be made if supervision was improved: 'The supervisor of a ground investigation should have geotechnical expertise and experience, as well as practical knowledge of the different techniques.'

All of the investigation contractors questioned expressed concern over the standards and quality of the documents received from non-geotechnical engineers or design professionals. Some contractors even suggested the number of specialist geotechnical firms dealing with SIs may have reduced.

Collation and conclusions of research

After the interviews, a comparison was made of the background literature leading up to the SISG documents, the documents themselves and the results from the interviews, to establish whether recommendations made before their publication in 1994 (see Historical perspectives box) were addressed. Comparison of the concerns raised in 2004 was undertaken.

Table 2 summarises the recommendations and conclusions of each of the three key references (Craig, Head, Uff and Clayton) which contributed to the writing of the SISG documents. Each were assessed to see if they have been addressed in the SISG documents. Only two were not addressed in the documents. The pink and blue books cover many of the recommendations. The yellow book has a far narrower focus on the introduction of a new national measurement system. Table 2 does, however, show that the SISG documents were aimed at addressing and resolving the identified problems with the industry 10 years ago.

Table 3 compares the issues expressed in 2004 with those addressed in the SISG documents. Out of the 12 main concerns identified in 2004, six were covered in the documents, in particular by the blue book - which is not widely used by any of the professionals. Were all parties to know and use the blue book, many concerns would immediately be addressed.


The SISG documents addressed many of the issues causing concern 10 years ago.

It would appear clients and some practitioners are not aware of the SISG documents in 2004.

The blue book was intended to be a fundamental step to the improvement of quality of SIs.However, as it does not contain material requiring constant reference (unlike the yellow book for example), it is not widely used.

The yellow book is the best known document, particularly due to the usefulness of the bill of quantities.However, with the introduction of electronic versions of the bill of quantities, schedules have become 'detached' from the supportive text, and this has led to misinterpretation and inappropriate use of the schedules.

The grey book is infrequently used because it is outdated.Major developments in contaminated land have occurred in the 10 years since it was published.

Concerns raised in 2004 about SI quality are different for each of the main sectors of the SI industry.

Many concerns raised in 2004 are covered in various levels of detail within the SISG documents published in 1994.


Professionals targeted in the original 1994 dissemination/advertisement campaign could have moved on or up. Therefore, there is a need to raise awareness of the issues discussed in the SISG documents, particularly with client organisations.

Despite being 10 years old, the documents are being used in the industry but to varying degrees.There is a need to possibly update and certainly re-advertise/disseminate the documents (particularly the yellow and blue books) to encompass new methods and developments in the SI industry.

A wider, and statistically more representative, sample of industry and client groups should be canvassed to verify these identified trends and measures to improve the quality of the SI process.


The authors greatly appreciate the time and views, honestly expressed, in the undertaking of the interviews. The views of current and former colleagues are also gratefully acknowledged.


Atkinson J (2004).What is the matter with geotechnical engineering. Private communication.

Clayton CRI (2001).Managing geotechnical risk. Thomas Telford Services.

Craig C (1986). The future of SI. In SI practice: Assessing BS5930, Geol Soc Eng Geol. Sp Pub No 2.

Diffin BT (2004). Procurement and quality of site investigations in the UK.MEng dissertation, University of Surrey, Department of Civil Engineering.

Head JM (1986). Planning and design of SI. In SI practice: Assessing BS5930, Geol Soc Eng Geol. Sp Pub No 2.

National Audit Office (2001).Modernising construction. HC87, 11 January, The Stationery Office.

Site Investigation Steering Group (1993). Site investigation in construction - Part 1: Without SI ground is a hazard. Thomas Telford Services.

Site Investigation Steering Group (1993). Site investigation in construction - Part 2: Planning, procurement and quality management.

Thomas Telford Services.

Site Investigation Steering Group (1993). Site investigation in construction - Part 3: Specification for ground investigation. Thomas Telford Services.

Site Investigation Steering Group (1993). Site investigation in construction - Part 4: Guidelines for the safe investigation by drilling of landfills and contaminated land. Thomas Telford Services.

Uff JF and Clayton CRI (1986).

Recommendations for the procurement of ground investigation. CIRIA Special Publication 45.

The return of SISG

The British Geotechnical Association has been tasked by the Insitution of Civil Engineers to reform the Site Investigation Steering Group to implement a review and revision of the four original site investigation documents.

All members of the original SISG, including government bodies, learned institutions and societies and trade associations have been invited to participate in the reconvened group.

Other relevant organisations have also been invited to contribute, 'with the intention of widening awareness of the site investigation industry and hopefully reducing the number of ineffective site investigations that are undertaken'.

For more information contact the BGA, tel: 020 7665 2233; email: bga@ice. org. uk

SI steering group documents

The pink book (Without site investigation ground is a hazard)

The pink book aims to highlight the possible risks of inadequate SI to clients or other design professionals who are designing an SI without aid from a geotechnical specialist. It gives examples of projects that have overspent and have overrun due to either inadequate SIs or from encountering unforeseen ground conditions.

The pink book reports that between 1968 and 1993 the prices of SIs were forced down so that only 16% of SIs were managed by geotechnical specialists, and that SIs were normally carried out at short notice.

It concludes SIs should be undertaken for every site; they need to be properly procured; they require supervision; and that ground hazards cannot be known for an entire site.

The blue book

(Planning, procurement and quality management)

The blue book was believed to be the document that would contribute to the shift in quality of SIs industry required. It focuses on planning, design and procurement and states that an investigation should only start once the following information has been determined:

a clearly defined purpose;

assessment of what information is required;

areas and depths of investigation;

the time required;

estimated cost.

The blue book recommends that a geotechnical adviser (GA) is associated with projects where the client's principal technical adviser (architect/structural engineer/project manager) is not competent within the field of geotechnics or geology and should be appointed in the early stages of the project.

The GA should be in charge of organising and determining SI requirements and the interaction of the structure with the ground. The GA should be a chartered engineer or geologist with at least eight years of practice after becoming chartered. Investigations should be carried out by a competent geotechnical contractor.

The blue book concludes the client should employ professionals with relevant experience and knowledge; that until the client understands the need for the correct professionals to be associated with a project, quality will not be delivered; that the principal technical adviser should translate the clients' requirement to relevant professionals; and that lines of communication should be maintained throughout the SI process.

The yellow book

(Specification for ground investigation)

The yellow book provides a consistent specification for SIs, methods of boring, sampling and insitu testing, and includes standard schedules and bills of quantities to help outline the scale and scope during procurement.

The grey book

(Guidelines for the safe investigation by drilling of landfills and contaminated land)

The grey book was aimed at raising awareness for what was, at the time, a low profile issue. It was an informative source of practice, useful information and guidelines. It concludes that anticipated hazards should be identified and information provided so the right techniques and measures could be implemented; that all contractors should carry appropriate insurances; that a site categorisation was adopted; and that appropriately trained staff should be provided depending on the site category.

Historical perspective on improvements in SI quality

In 1986 Craig highlighted what he believed to be the future of the SI industry:

Improvements in technology would not lead to substantial improvement in boring techniques or methods.

Sampling methods would improve, and would be more focused on the production of continuous profiles.

Geophysical techniques were likely to improve and play a greater role.

Insitu testing was likely to be improved and to expand at the expense of conventional testing.

The reliance on the experience and knowledge of the geotechnical engineer would continue.

Trial pitting would continue to play an important role.

Craig suggested SI practice in the UK would remain unchanged, unless there was appropriate legislation. It seemed improbable that BS5930: 1981 would become a statutory requirement. It was possible that specifically qualified professionals would specify work such as laboratory testing, borehole logs and field testing and that formal procedures for quality assurance were likely to emerge with time.

He concluded that in the UK there was no standard procedure for organising SIs. For an SI to be successful it was essential therefore to ensure the objectives of the end user were constantly considered and that fieldwork was conducted by one or more of either a geotechnical specialist, a geotechnical contractor, a geotechnical department of large consultants, drilling contractors and independent laboratories.

Head (1986) stated that a successful investigation could only be achieved through thorough planning and design. Lack of planning and design often resulted in inadequate design for foundations and contributed to the overall construction costs.

He pointed out that BS5930 did not put sufficient emphasis on qualified and experienced geotechnical engineers controlling the investigations and closely supervising the works, and that allocation of more realistic funds was required to enable sufficient planning, ground investigation, reporting and monitoring.

By taking these actions, he said, SI quality would improve and many common shortcomings would be avoided. He concluded that BS5930 needed to cover planning and design and that a more formal approach was needed for these stages of SI.

Uff and Clayton (1986) made the following recommendations:

A geotechnical awareness programme was needed for clients, to highlight the importance of ground investigations, particularly with the involvement of geotechnical specialists.

A guide to procurement should be produced.

A new national measure of works was required for SIs.

National guidelines should be produced, detailing the extent and intensity of the investigation required to indicate the minimum requirements for a range of civil engineering projects.

All SIs should be done under a uniform quality assurance warranty.

All factual reports should be made available as early as feasibly possible to all members of the party involved with the project.

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