AGS – Association of Geotechnical and Geoenvironmental Specialists

You arrive on site with detailed plans of the buried services. The electricity and telecommunications can be readily confirmed with your Cable Avoidance Tool (CAT); the route of the gas main, sewer and water main are visually located through pavement scarring and covers. The services are all found to be exactly at the location and depth expected and your drilling is completed without incident.
Oh that it were so simple. On how many sites is the information provided in respect of buried services woefully inadequate? Most often the electricity, water and sewerage plans show the detail in the roads surrounding your site but precious little as to the routing within the site boundary. The power loops to on-site street lighting and the installations for telecommunications are seldom shown on such drawings and remain to be discovered.
In the site investigation industry the biggest risk to the safety of operatives is arguably that of striking buried services and unlike many theoretical or perceived risks this is real. A JCB rarely loses an argument with a buried pipe or cable and the implications of ripping through a gas main and electricity supply together are only too obvious.
Clause 11 of the CDM regulations 2007 sets out clearly the duties of designers, particularly in taking “all reasonable steps to provide with his design sufficient information…”. This begs the question as to whether sufficient attention is being given to acquiring detailed and accurate services information prior to breaking ground. In most developments it would appear that gathering this information is of low priority and reliance is placed on the site crew to dig a 1.2 m deep inspection pit.

Detailed information concerning buried services is obviously going to be required at some stage in the project. The key point, therefore, becomes when rather than if the information is to be obtained. A number of commercial providers will obtain all of the services information relatively rapidly and relatively economically. Going back to responsibilities under CDM; is gathering this information in advance of breaking ground a ‘reasonable step’?

Well yes, responsible designers should be advising their clients that detailed current services information should be acquired at the very earliest opportunity. It must be seen as an equally important and “routine” activity as a topographic survey of a site and will be of benefit to all parties as the design progresses. Crucially, however it contributes significantly to reducing the risk of injury to the ground investigation contractor.

Surely it would be better for all parties if the ideal set out in the first paragraph applied to all sites.

Martin Cooper
Principal Geotechnical Engineer
Geotechnical and Environmental Associates Limited

The need, quality and sufficiency of site investigations has been of paramount importance since the early 1960s and the issue of client awareness of the benefits of site investigation have been well-discussed within construction industry.

In the late 1950s, Foundation Engineering produced the film “The problem below” to address this issue. The film described and projected the need and benefits of carrying out site investigations. A project in Boness in Scotland was selected for filming.

I recently saw this film again for the first time in about 20 years. Although the aircraft at Glasgow Airport was a Viscount turbo prop and the drilling rig a Conrad “slip rope” rig (with square boring rods and tools), the requirements for quality, sufficiency, client understanding and “buy-in” were well portrayed and appeared to be well understood.

Today’s clients are more likely to develop a project and move on as fast as possible to the next one, with many (if not all) the responsibilities and liabilities being devolved down the supply chain to architects, consultants and builders, by the use of sometimes onerous terms of engagement, including multi-assigned warranties. In dealing with these clients, the ground is generally taken for granted. When projects involve the redevelopment of brownfield sites the concerns of contamination and perceived high risk associated with this seem to become more evident, however.

Local planning authorities’ requirements and stipulations for such sites generally ensure the client and their team consider the geoenvironmental issues at pre-planning submission stage. The desire to obtain planning permission and the need to tackle contamination risk issues act as drivers for undertaking geoenvironmental investigations. In many instances however, the initial site investigation ignores some of the main geotechnical issues. How often is a geoenvironmental site investigation – which usually does not even include the most basic insitu geotechnical tests such as a standard penetration test – offered to a piling contractor for them to design, price and carry out foundation work?

When clients are in the early stages of conceiving a project they need to establish a funder, insurer and a project management team as well as the usual engineering consultancy service providers. The consultancy service providers called upon in the initial stages are generally architects and structural engineers, who usually may only see the above ground structure. The introduction of the geotechnical adviser into a project team at an early stage has been strongly advocated over the past ten years by the Institution of Civil Engineers and Association of Geotechnical and Geoenvironmental Specialists (AGS) but in many cases this is not happening.

The structural engineers in some instances see themselves as capable of undertaking this geotechnical role or are unaware of the good practice guidelines laid down by AGS and others. To address the situation and develop more client awareness, the industry needs access to the commercial team. To this end, AGS will shortly be completing its project benchmarking scheme, which will provide an assessment and score for each project where there is ground engineering site investigation input.

The scoring system is based on Key Performance Indicators (KPIs) for the particular geotechnical activities undertaken within ten selected groupings, including one for client satisfaction. This initiative is likely to eventually provide a substantial database of assessed projects, which can then set the norm for good, moderate and poor site investigation input. Information from project benchmarking and KPI scoring can also be developed to provide the client’s commercial team with a simple “traffic light” risk assessment of the project. It will then be simple to show the benefits of carrying out a full ground engineering site investigation service – desk study, phased intrusive ground study, associated supervision, laboratory testing and ground engineering advice.

The AGS and Federation of Piling Specialists recently had discussions concerning the quality and sufficiency of site investigation reports provided to foundation contractors, and agreed to consider a joint advisory paper, likely to be called “Guide to foundations”, published as part of the AGS Clients Guides. CDM regulations are also expected to be included. AGS members recognise the need for the Site Investigation Steering Group (SISG) series of publications to be redrafted and published as soon as possible, as the 1993 editions are well out of date. There are plans within the fraternity to arrange for the SISG Specification (Yellow book) to be redrafted within the next year or so.

Jim Cook is chairman of the Association of Geotechnical and Geoenvironmental Specialists and director of Buro Happold’s Ground Engineering group.

The following article originally appeared as a ‘Talking Point’ in Ground Engineering, June 2005.

Association of Geotechnical & Geoenvironmental Specialists

The Contractor ’s Problem

The site investigation industry is launching a series of initiatives to improve client awareness, says Jim Cook.