A. H. Marsh, STATS Limited, St Albans
The author presents an excellent overview of the concept of geotechnical risk management and how it might be applied. Most geotechnical specialists (geotechnical engineers and engineering geologists) achieve a level of experience and competence to practise geotechnical risk management within five to ten years of graduation. Indeed, subconsciously geotechnical specialists often do adopt an undocumented form of geotechnical risk management to guide their judgements required at various stages in a typical investigate-design-and-construct project. However, there appears to be little chance that the techniques will be overtly applied to the majority of construction projects in which geotechnical specialists become involved because of the current structure of the construction industry and in particular the methods of procurement used to obtain geotechnical expertise.
The construction industry in terms of its client base and practices remains fairly heavily polarised into a civil engineering sector and a building or structural engineering sector. The civils sector continues to involve the use of civil engineering design organisations that, almost without exception, now have geotechnical specialists on their staff. These organisations typically have a leading role to play, either being employed directly by the ultimate client, under traditional forms of construction procurement, or by the contractor in design-and-build projects. In either case the geotechnical specialist has the opportunity to promote the benefits of geotechnical risk management to the project team and, to a degree, to unilaterally introduce it into the project. It is probable that this process is already occurring and it should certainly be encouraged where appropriate.
The civils sector accounts for the minority of projects in which geotechnical specialists become involved. In overall monetary value terms this may not be the case but, in a simple analysis of the number of projects undertaken in the United Kingdom each year, it is estimated that there are two to three times as many building sector projects as civils sector projects in which geotechnical specialists are involved. Because the majority of these projects do not involve the use of a lead engineering design organisation with geotechnical specialists on its staff, the geotechnical input is procured and managed by nonspecialists and often not even by engineers. This state of affairs is at the heart of much that is unsatisfactory about the role and contribution of the geotechnical specialist in improving the delivery and cost control of building-led development projects.
It is acknowledged that clients themselves, project management organisations, architects, surveyors or structural engineers will, most likely, continue to procure the specialist geotechnical input to their projects. It therefore seems essential that geotechnical specialists promote the concept of the ‘phase 1 geotechnical study’ with the same degree of success that environmental consultants have achieved with the phase 1 environmental study/audit. The spectrum of procuring organisations referred to above for building projects appears to have no difficulty in grasping the need for and benefit of phase 1 environmental studies. Indeed, my colleagues and I at STATS have been providing some enlightened clients with combined phase 1 geotechnical and environmental studies for many years.
The essence of a phase 1 geotechnical study is that it goes beyond the stage 1 desk study and site reconnaissance referred to in BS 593030 and it is interesting to note that BS 5930 does not specifically mention the need for a report even to be produced at stage 1. In the phase 1 environmental study report, the concept of the source-pathway-receptor risk assessment framework is introduced to the project design team at the earliest possible moment. A preliminary, qualitative appraisal of the likely sources, pathways and receptors is made on the basis of the desk study and site reconnaissance. From this, important decisions can be made at a very early stage on the viability of the project and on priorities for moving forward, including the design of the most appropriate intrusive ground investigations.
In a similar manner the phase 1 geotechnical study report should contain a preliminary, qualitative or possibly semi-quantitative, appraisal of ground-related hazards, the likelihood of their presence in a way that could affect the proposed development and their possible consequences on the development. The ground-related hazard risk assessment concept is then introduced to the project design team with a status equivalent to the source-pathway-receptor risk assessment in the phase 1 environmental study and with similar benefits to the project.
The complete phase 1 geotechnical study report typically should contain, inter alia, the following four elements
findings of the desk study and site reconnaissance, including any thematic mapping
preliminary ground-related hazard risk assessment
preliminary geotechnical/foundation engineering appraisal
recommendations on the scope, design and staging of ground investigations.
The phase 1 geotechnical study provides non-specialists with the opportunity to procure to the project design team genuine geotechnical expertise, for a cost typically equivalent to a few days' time-charge fees for a geotechnical specialist. It does not commit the client to some, effectively pre-determined, scope of ground investigation compiled by a non-specialist. This is typically the case at present with the procurement by competitive quotation of a firm of site investigation specialists under a package to carry out a desk study (scope often completely undefined) and ground investigation (the cost of which usually far outweighs the desk study).
In conclusion, the author's promotion of the concept and benefits of more effectively managing geotechnical risk are endorsed. It is proposed that the commissioning by clients of a formal phase 1 geotechnical study in which the findings of a preliminary ground-related hazard risk assessment are presented is the best way to instigate the process of geotechnical risk management on a project. The phase 1 geotechnical study is also perceived to have other benefits in improving the overall process of site investigation in the United Kingdom.
Author's reply
Mr Marsh notes that the client base for construction is polarised, and that non-civils work accounts for the vast majority of the projects carried out in the UK. Clearly it is most important that where projects do not have a lead civil engineering designer with geotechnical expertise, a preliminary geotechnical risk assessment should be carried out. The proposal of a phase 1 geotechnical study seems to fit that bill, and should serve to warn clients and their advisors of the hazards and associated risks inherent in their proposed development.
Mr Marsh proposes four elements that should be contained (inter alia) in a phase 1 geotechnical study. In addition, however, I believe that important contributions will be made both to the risk management and to the cost-effectiveness of geotechnical aspects of construction by carrying out conceptual design at an early stage. Since conceptual design is required in order to plan effective ground investigation (for example, one cannot know how deep the boreholes are to be unless a decision about the type of foundation to be used has been made), a high level of geotechnical skill will always be required at these earliest stages of all projects.
